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Dr. Samer Hattar: Timing Light, Food, & Exercise for Better Sleep, Energy & Mood | Huberman Lab #43



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Welcome to the Huberman Lab Podcast,
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where we discuss science and science-based tools
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for everyday life.
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I'm Andrew Huberman, and I'm a professor of neurobiology
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and ophthalmology at Stanford School of Medicine.
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Today, I have the pleasure of introducing Dr. Samir Hattar
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as my guest on the Huberman Lab Podcast.
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Dr. Hattar is the chief of the section
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on light and circadian rhythms
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at the National Institute of Mental Health
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in Bethesda, Maryland.
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Dr. Hattar has many important discoveries to his name.
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He was one of a handful of groups
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that discovered the light-sensing neurons in the eye
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that set the circadian clock.
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This was a fundamental discovery made in the early 2000s
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that has led to an enormous number of additional discoveries
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on how light regulates our sleep, our immune system,
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our mood, mental health, metabolism, feeding,
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and many other important processes.
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If ever there was somebody who understands
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how all of these processes interact
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and can inform best practices for our daily behaviors,
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it's Dr. Hattar.
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During our discussion today,
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Dr. Hattar answers questions that are absolutely essential
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for us to know about our health and wellbeing.
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For instance, how to align our sleep schedule
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with our activity schedule, such as exercise,
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and how to align light activity and exercise
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with our feeding rhythms.
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He presents a new model of how light activity
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and feeding rhythms converge to support optimal health,
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and when those are not aligned correctly,
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how our mental and physical health can suffer.
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It's a discussion that is rich with scientific mechanism,
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made clearly, of course, so everybody can understand,
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as well as specific protocols to deal with shifts
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in day length, shifts in activity,
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and in order to optimize sleep, metabolism,
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and wellbeing of various kinds.
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I learned so much from Samir, as I always do.
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He is an absolute wealth of knowledge
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on all things related to light and circadian rhythms,
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physiology, and neuroscience.
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I don't think you'll find anyone else
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as knowledgeable about these topics as Samir,
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and so I'm delighted that he joined us here on the podcast
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to share this information.
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Before we begin, I'd like to emphasize that this podcast
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is separate from my teaching and research roles at Stanford.
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It is, however, part of my desire and effort
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to bring zero cost to consumer information about science
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and science-related tools to the general public.
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In keeping with that theme,
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And now my conversation with Dr. Samer Hatar.
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Samer, thanks for sitting down with me.
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My pleasure.
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Yeah, we go way back.
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So you are best known in scientific circles
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for your work on how light impacts mood,
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learning, feeding, hunger, sleep, and these sorts of topics.
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So just to kick the ball out onto the field, so to speak,
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how does light impact the way we feel?
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So when I get up in the morning,
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I have the opportunity to interact with light
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in certain ways or to avoid light in certain ways.
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I have the opportunity to interact with sunlight
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or with artificial light.
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Maybe you could just wade us into what the relationship is
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between light and these things
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like mood and hunger, et cetera.
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Sure.
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So I mean, you do appreciate the effect of light for vision.
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So when you wake up in a beautiful area, beautiful ocean,
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light is essential.
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The sunrise, the sunset, blue sky, beautiful mountains.
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So that's your conscious perception of light.
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But light has a completely different aspect
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that is independent of conscious vision
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or image-forming functions.
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And that's how it regulates
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many important functions in your body.
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I think the best that is well-studied and well-known
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is your circadian clock.
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And the word circadian comes from the word circa,
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which is approximate, and dn is day.
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So it's an approximate day.
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Why is it an approximate day?
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Because if I put you or any other human being
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who have a normal circadian clock in a constant conditions
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with no information about feeding time, about sleep time,
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about what time it is outside,
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you still have a daily rhythm,
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but it's not exactly 24 hours.
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So it will shift out of the solar day
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because it's not exactly 24 hours
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and hence the name circadian.
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So just to ask a quick question about that,
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when you say you have this about 24-hour rhythm,
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how does that rhythm show up in the tissues of our body?
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Great, so great question.
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So it shows up at every level that we know we studied.
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It shows up at the level of the cell,
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it shows up at the level of the tissue,
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and it shows up at your behavior.
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The most obvious for you is your sleep-wake cycle.
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You sleep and you're awake and sleep at the 24-hour rhythms.
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And if you measure the sleep-wake cycle
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of humans who are maintained in constant conditions,
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you will see that the period length of the sleep rhythm,
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on average, is more than 24 hours.
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In humans, it's 24.2 hours.
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So you'll be drifting.2 hours every day
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out of the solar day if you don't get the sunlight.
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So the sunlight adjusts that approximate day
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to an exact day, so now your behavior is adjusted
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to the light-dark environment or the solar day.
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Okay, so if I understand correctly,
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if I were to go into a cave or I were to be
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in constant light and I didn't close my eyes
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in constant light, that I would still sleep
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in one coherent bout and I would still be awake
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for more or less one coherent bout, maybe a nap.
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But the total duration of my day, so to speak,
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would be a little bit longer than 24 hours.
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But if I'm in a condition like most people are,
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where the sun goes up and the sun goes down
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and I have some understanding of that sunrise and sunset.
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You don't have to have the understanding.
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You don't have to have conscious understanding.
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You have the detection.
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So circadian photoentrainment is the word we use
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in training the circadian clock to the photic environment.
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It's completely subconscious.
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You're not aware of it.
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It's not like vision or image forming
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where you actually know what you're looking at.
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So it's all hypothalamic.
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It's part of the brain that is not consciously driven.
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So you actually do not know when it happens
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or when it doesn't happen.
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And that's what we'll get into when I tell you
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why light affects your mood and why sometimes
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people don't know how to deal with light
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to improve their mood, for example.
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Okay, so this is a subconscious vision.
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Yes.
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Okay.
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Before you tell us about how light impacts mood,
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I'm curious, what is the relevance of adjusting
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this clock from a little bit longer
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than 24 hours to 24 hours?
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I mean, it seems like a small difference.
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24 hours and 40 minutes or 24 hours?
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Like, what's the relevance?
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I mean, why should we care about that short difference?
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So let's do the math.
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If you shift out 0.2 hours a day,
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in five days you're shifting out one hour.
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So you're literally one hour off
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in your social behavior in five days.
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In 10 days, you're two hours off.
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And if you're an organism that is living in the wild,
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shifting out of the right phase of the cycle,
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you could either miss food or you could become food.
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So it's really essential for survival.
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I think it's one of the strongest aspects of survival
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for animals to have the anticipation
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and the adjustment to the solar cycle.
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And for humans as well, when you say animals,
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I'm assuming that applies to us.
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Absolutely, yeah.
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I see.
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So even though it's just a short bit longer than 24,
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if that accumulates over days,
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then you could find yourself very much out of phase
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with the rest of your species, essentially.
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So let's say it's 0.2 hours.
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So in five days, it's one hour.
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In 25 days, it could be five or six hours.
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You could be in New York and you're feeling
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as if you traveled from New York to London.
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So you will be having jet lag in New York,
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even though you didn't do a jet lag travel.
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So it's very important for the adjustment.
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And if we have time, maybe we could talk about
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why this is important for seasonality,
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because also it allows animals to anticipate
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the change in season.
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And the more you're high in the north or the south,
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the more that these weather changes occur very harshly
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and you have to be ready for them.
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And that happens in us as well.
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All right, we will definitely get into seasonality.
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Okay, so we've got this subconscious vision
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that aligns us with the turn of the earth.
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How does that work?
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What is the machinery that allows that to happen?
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And how does that machinery work?
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Yeah, so we knew that in mammals, including us,
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we are mammals, humans,
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that the eyes are required for this function.
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So if humans are born without eyes
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or the optic nerves are damaged,
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humans are not able to adjust to the solar cycle.
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So we know that the eyes are required.
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And since we thought we knew about the eyes a lot
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before 2000, we thought that-
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What did you say, before the year 2000?
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Before the year 2000, yes.
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We thought it's these photoreceptors in your retina
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that allow you to see.
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So in the human retinas,
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there are two types of photoreceptors.
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They are called rods and cones because of their shapes.
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And these rods and cones simply take the photon energy,
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which light is made of,
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and they change it in a way to an electrical signal
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that allow us to build the image of the environment
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in our cortices.
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Subconsciously?
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Consciously, in this situation, because it's vision, right?
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It's image-forming vision, it's a visual cortex
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and associative cortices,
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which allow you to build conscious perception
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of the environment.
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However, people have found,
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including me with the work of David Berson
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and Ignacio Provencio,
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that there is a subset of ganglion cells.
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The ganglion cells are the cells that leave the retina,
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their axon, leave the retina, and project to the brain.
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So these words are stored to only relay
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rod and cone information from the light environment
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to the brain.
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We found that a small subset of these ganglion cells
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00:14:01.520
are themselves photoreceptors that were completely missed
link |
00:14:04.760
in the retina.
link |
00:14:06.020
And these are the photoreceptors
link |
00:14:08.080
that relay light environment subconsciously
link |
00:14:12.080
to the areas in the brain that have and house
link |
00:14:15.020
the circadian clock or the circadian pacemaker,
link |
00:14:18.100
which adjusts all the clocks in our bodies
link |
00:14:20.560
to the central brain clock that allows them to entrain
link |
00:14:23.840
to the 24 hour light dark cycle.
link |
00:14:27.400
Incredible.
link |
00:14:28.240
So in the year, as I recall,
link |
00:14:30.040
because I was a graduate student at the time,
link |
00:14:31.520
in the year 2000, there was this landmark discovery
link |
00:14:34.420
made by you, Ignacio Provencio, David Berson, and others,
link |
00:14:37.960
that these cells exist that can communicate
link |
00:14:40.320
day and night information to the brain
link |
00:14:42.680
in this very small subset of cells.
link |
00:14:45.440
Since then, I've heard, but maybe you can confirm or refute,
link |
00:14:49.200
that this system that connects the eyes
link |
00:14:52.880
to the rest of the brain
link |
00:14:54.340
is actually the most ancient form of vision,
link |
00:14:56.300
that this is probably the form of vision
link |
00:14:58.200
that some early version of human beings had
link |
00:15:01.480
before they had pattern vision,
link |
00:15:03.080
before they could see colors and shapes and motion
link |
00:15:05.200
and all that.
link |
00:15:06.420
And that the same cells that perform this role
link |
00:15:11.340
are actually similar to insect eyes.
link |
00:15:14.820
I think I heard David Berson say once
link |
00:15:16.480
that we actually have a little bit of the fly eye
link |
00:15:19.040
in our eye.
link |
00:15:19.860
What's he talking about?
link |
00:15:20.880
Yeah, so it's really interesting, actually,
link |
00:15:23.460
because these same IPRGCs we discovered,
link |
00:15:27.040
they contribute a little bit to image formation
link |
00:15:29.520
and now work from Tiffany Schmidt,
link |
00:15:31.360
specifically have proven that they do contribute
link |
00:15:34.160
to image forming functions.
link |
00:15:36.240
But they contribute to very limited aspect
link |
00:15:41.160
of image formation.
link |
00:15:42.000
So it fits your hypothesis
link |
00:15:43.640
that these are an ancient photoreceptors.
link |
00:15:45.800
The other thing that adds to that hypothesis
link |
00:15:48.640
is that they are expressed in cells
link |
00:15:50.140
that don't have any modification
link |
00:15:52.040
that make them look like photoreceptors.
link |
00:15:54.080
So the photoreceptors that I told you about
link |
00:15:56.300
that are important for vision, image formation,
link |
00:15:59.800
they have very specialized structures
link |
00:16:02.360
that allow them to pack these structures
link |
00:16:04.640
with photopigments.
link |
00:16:05.780
These are the photo detecting proteins.
link |
00:16:09.040
So they could detect a high sensitivity of photons
link |
00:16:12.120
that pass through them.
link |
00:16:13.640
These new photoreceptors don't have
link |
00:16:18.160
these specialized structures.
link |
00:16:20.400
So they just really need a lot of light at the time.
link |
00:16:24.440
We thought they need a lot of light to be activated.
link |
00:16:28.080
So that's why we think they are ancient
link |
00:16:30.080
and that's why I think they adjust to ancient functions
link |
00:16:33.400
that are as important as regulating your body,
link |
00:16:36.760
circadian clock to the solar environment,
link |
00:16:39.240
to solar day or to the light cycle.
link |
00:16:42.160
So you mentioned IPRGCs, intrinsically photosensors.
link |
00:16:45.280
So these are cells that connect the eye of the brain
link |
00:16:47.040
that behave like photoreceptors, essentially.
link |
00:16:49.320
And then you mentioned melanopsin,
link |
00:16:51.680
which is the actual pigment that converts the light
link |
00:16:54.560
into the electrical signal, more or less.
link |
00:16:57.520
And my understanding is that melanopsin
link |
00:17:00.200
was identified first in frog melanophores.
link |
00:17:04.140
So does that mean that we have like little pieces
link |
00:17:06.080
of frog skin in our eyes?
link |
00:17:08.000
So honestly, David Berson say you have a fly in your eye
link |
00:17:10.940
because it sounds better.
link |
00:17:12.460
The more accurate I think is that you have a frog skin
link |
00:17:15.520
in your eye, it's not as catchy.
link |
00:17:17.600
But really melanopsin, really the name melanopsin
link |
00:17:20.920
is from melanocyte opsin.
link |
00:17:23.240
So it's melanopsin because it was found
link |
00:17:25.360
in the frog melanocytes.
link |
00:17:26.680
You know the frogs can change their color depending on light
link |
00:17:30.280
and melanopsin drives this response.
link |
00:17:32.720
So when Ignacio Provencio first discovered
link |
00:17:35.920
these opsins in frogs, luckily he was smart enough
link |
00:17:39.240
to see if they are expressed in the frog eye.
link |
00:17:41.720
They were expressed in the frog eye
link |
00:17:43.340
and it what appears to be retinal ganglion cells,
link |
00:17:45.840
which I told you the one that connect the eye to the brain.
link |
00:17:48.480
He had the insight to go and see if they are expressed
link |
00:17:51.040
in the monkey eye and he found that they are also expressed
link |
00:17:54.400
in what appears to be retinal ganglion cells.
link |
00:17:56.760
And really that what opened the field wide open.
link |
00:17:59.480
Then David Berson did the seminal experiment
link |
00:18:02.920
where he went to the brain where the central oscillator,
link |
00:18:07.200
the oscillator that drives circadian rhythm in the brain
link |
00:18:09.840
called the suprachiasmatic nucleus
link |
00:18:11.840
that has been known for many years to receive retinal input.
link |
00:18:15.800
And he labeled the cells that project there
link |
00:18:18.360
and then he found that even if you destroy rods and cones,
link |
00:18:21.320
you could get light responses from these cells.
link |
00:18:23.560
So you could imagine he nearly fainted
link |
00:18:26.380
when he saw that these cells can respond independent,
link |
00:18:29.760
completely in the absence of rod and cone input.
link |
00:18:32.720
Yeah, I'll never forget reading those papers in 2000, 2001.
link |
00:18:36.840
I was at the meeting in DC when Ignacio,
link |
00:18:40.520
we call him Iggy, showed this image of this,
link |
00:18:43.720
basically what is frog melanophores in the human eye.
link |
00:18:47.200
And everyone was like, oh my goodness, this is the thing.
link |
00:18:50.700
And I want to get into how light actually
link |
00:18:52.960
can control circadian rhythms at the moment.
link |
00:18:55.240
But I think it's worth mentioning now
link |
00:18:57.320
that people who are pattern vision blind,
link |
00:19:00.120
so people who cannot see and no conscious vision,
link |
00:19:03.960
but have eyes, many of them still have these cells,
link |
00:19:07.620
these melanopsin intrinsically photosensitive cells
link |
00:19:10.080
and can essentially match or entrain, as we say,
link |
00:19:14.240
onto the light dark cycle.
link |
00:19:16.000
In fact, they possibly have no problems
link |
00:19:18.000
in circadian photo entrainment.
link |
00:19:19.400
They'll have enormous sleep-wake cycle.
link |
00:19:21.560
But they're totally blind.
link |
00:19:22.580
But they are totally image blind.
link |
00:19:24.160
And what's really interesting is that,
link |
00:19:26.620
and this story I heard from Chuck Sizler,
link |
00:19:28.480
so I'll give him credit,
link |
00:19:29.800
that some of these people who are image blind,
link |
00:19:32.200
usually they get dry eyes and they give them a lot of pain.
link |
00:19:35.620
And doctors used to think, oh, since they are image blind
link |
00:19:39.240
and they're getting dry eye,
link |
00:19:40.400
why don't you just remove their eyes?
link |
00:19:42.060
They're not using them anymore.
link |
00:19:43.640
And the minute they would remove their eyes,
link |
00:19:45.960
they start having cyclical sleep problems,
link |
00:19:48.200
indicating that now they are not entraining
link |
00:19:50.720
to the light dark cycle and are having cyclical jet lags
link |
00:19:54.600
when their clock shifts through the light dark cycle.
link |
00:19:57.960
That's really interesting.
link |
00:19:58.920
And I hear from a number of blind people,
link |
00:20:02.480
in my various aspects of my job,
link |
00:20:04.560
and a lot of them have issues with sleep, I think,
link |
00:20:08.160
in part because they don't realize
link |
00:20:09.960
that they too need to see light
link |
00:20:11.540
at particular times of day or night
link |
00:20:13.160
in order to match their schedule.
link |
00:20:15.840
Well, I think that's a perfect segue for us
link |
00:20:18.280
to talk about how light and viewing light
link |
00:20:22.280
can impact our sleep-wake rhythms.
link |
00:20:24.560
And then we will move into some of the other ways
link |
00:20:27.120
in which light can impact other forms of bodily function.
link |
00:20:30.320
Yeah, so I love the way you set it up
link |
00:20:33.240
because one of the most interesting and difficult aspect
link |
00:20:37.240
of trying to educate people about light effect
link |
00:20:40.520
on subconscious vision is that it's subconscious.
link |
00:20:43.800
So we're all aware of what we think is intensity
link |
00:20:47.200
because we see the room.
link |
00:20:48.580
But if you talk to people who know how to take photographs
link |
00:20:52.400
and stuff like that,
link |
00:20:53.560
they know that the intensity varies greatly.
link |
00:20:56.140
But our system, because we have to see the same way
link |
00:20:59.100
in very bright conditions and very dim conditions,
link |
00:21:02.140
we're not very good at estimating intensity consciously.
link |
00:21:06.080
So when you try to tell people about intensity,
link |
00:21:08.440
you really struggle because they think they know intensities
link |
00:21:11.580
but they really don't.
link |
00:21:12.680
You mean light intensity.
link |
00:21:13.700
Light intensity.
link |
00:21:14.760
So that the cones themselves have an incredible ability
link |
00:21:18.880
to adapt to different light conditions.
link |
00:21:21.480
So you can see at all different conditions,
link |
00:21:23.520
otherwise it'd be a disaster.
link |
00:21:24.880
You know, if you don't change the setting on your camera
link |
00:21:28.000
and you go from inside the room to the outside,
link |
00:21:30.040
it becomes completely white, you don't see anything.
link |
00:21:32.640
So if your cones don't adapt to the environment,
link |
00:21:36.000
then you're not gonna be able to see in this room
link |
00:21:38.560
and on the beach, right?
link |
00:21:41.000
But the problem is your IPRGCs,
link |
00:21:44.200
the cells that we talked about,
link |
00:21:46.400
they measure intensity pretty well.
link |
00:21:48.600
They really know what intensity is.
link |
00:21:50.380
They have a very good linear measurement of intensity.
link |
00:21:53.240
They don't adapt as well,
link |
00:21:54.880
they don't adapt actually that much, to be honest.
link |
00:21:58.480
So that tells you that subconsciously the system is used
link |
00:22:03.320
to measuring light intensity in a natural environment.
link |
00:22:06.520
Because when you're in a natural environment,
link |
00:22:08.800
you don't have industrialized lighting,
link |
00:22:12.120
then your system is functioning very well.
link |
00:22:15.520
But now when we change these environments,
link |
00:22:18.140
we could really mess up ourselves.
link |
00:22:19.640
So you have to teach people how to understand intensity.
link |
00:22:23.440
And that's something that you have to explain to people.
link |
00:22:25.960
And I think I love to do it myself.
link |
00:22:27.960
I do it in what is called the lowest amount of light
link |
00:22:31.240
required to allow you to see comfortably.
link |
00:22:33.520
So you have to do this as a fun experiment.
link |
00:22:36.460
Okay, so explain to me how this goes.
link |
00:22:38.760
And maybe we could break it up in the day
link |
00:22:40.600
into three or four parts.
link |
00:22:42.880
So let's say, assuming that most people wake up
link |
00:22:45.720
in the morning, as opposed to night shift workers, et cetera,
link |
00:22:48.560
we could talk about later.
link |
00:22:49.680
But they wake up in the morning,
link |
00:22:51.500
so let's divide the day into quarters.
link |
00:22:52.880
What is the proper way to interact with light
link |
00:22:57.040
in the first part of the day?
link |
00:22:59.640
So I honestly think the easiest thing is waking up.
link |
00:23:02.880
Get as much light as you can.
link |
00:23:05.240
It's your eyes.
link |
00:23:06.200
Yeah, it's really nice.
link |
00:23:07.460
Your system is primed.
link |
00:23:08.840
If you're entrained, it's primed to get light.
link |
00:23:10.880
The sun should be out.
link |
00:23:12.640
Most animals in the wild,
link |
00:23:14.040
they actually seem to track the sun.
link |
00:23:16.280
The sun has a huge influence on life on earth.
link |
00:23:18.720
It's actually, life on earth is because of sun.
link |
00:23:21.880
So that's easy.
link |
00:23:24.040
In the morning, when you wake up, you need light.
link |
00:23:26.000
Okay, so what is the behavioral practice
link |
00:23:28.040
that you recommend?
link |
00:23:29.960
Does it, let's say somebody is in a condition
link |
00:23:32.120
where there's a lot of cloud cover.
link |
00:23:33.680
Yeah.
link |
00:23:34.520
Is it important to get outside?
link |
00:23:35.600
So I have to tell you, the cloudiest day
link |
00:23:37.900
is gonna be much more brighter than your room.
link |
00:23:40.120
You could ask any photographer.
link |
00:23:42.320
A cloudy day, unless it's really dark, dark clouds,
link |
00:23:45.460
usually cloudy days have much more bright outside
link |
00:23:48.800
than inside the room,
link |
00:23:49.840
even when you have good lighting inside the room.
link |
00:23:52.740
So I think in the outside is usually,
link |
00:23:55.960
even when it's cloudy,
link |
00:23:56.920
you're gonna get enough intensity
link |
00:23:58.560
to help you adjust your cycle to the day-night cycle.
link |
00:24:01.740
So how long do you, these are general rules of thumb,
link |
00:24:05.020
but how long do you recommend people go outside?
link |
00:24:07.080
So if you do it daily, you possibly need very,
link |
00:24:09.920
if you do it daily, because remember,
link |
00:24:11.680
this thing is gonna happen on a daily matter.
link |
00:24:13.480
So it's like 15 minutes.
link |
00:24:14.320
So the clock is tracking it on a regular day.
link |
00:24:16.080
Absolutely, it's photon counting, it's tracking,
link |
00:24:19.600
I would say 15 minutes.
link |
00:24:20.680
If you don't do it daily, you may wanna increase it.
link |
00:24:23.600
And we'll talk about when you travel what you could do.
link |
00:24:26.000
But yeah, 15 minutes should be fun.
link |
00:24:27.960
You do it more, it doesn't hurt.
link |
00:24:29.840
And through a window, I was,
link |
00:24:31.360
my understanding is that through a window,
link |
00:24:33.200
it dramatically decreases
link |
00:24:34.440
the amount of light energy coming in.
link |
00:24:35.880
It depends of how, you know,
link |
00:24:37.680
how thick the windows are and how dark they are.
link |
00:24:40.200
So it, but it's also nice to go outside
link |
00:24:42.840
and to feel the season.
link |
00:24:44.440
Sunglasses off.
link |
00:24:46.040
I don't use sunglasses.
link |
00:24:47.400
Yeah, but you have the, your Jordanian photo pigment,
link |
00:24:50.600
you know, so yeah.
link |
00:24:52.200
Whereas my eyes are very sensitive, right?
link |
00:24:54.320
No, so I, but I personally,
link |
00:24:56.840
you know, if I'm in the shade
link |
00:24:58.200
or if it's not incredibly bright,
link |
00:25:00.200
I try to, especially in the morning,
link |
00:25:02.000
but I'm also an early person.
link |
00:25:03.560
So we have to differentiate between early.
link |
00:25:05.200
What time do you wake up?
link |
00:25:06.200
I wake up at 4.30 in the morning.
link |
00:25:07.760
But the sun isn't out yet.
link |
00:25:08.840
It's not out yet, so it's.
link |
00:25:10.120
So what do you do?
link |
00:25:10.960
You turn on artificial lights?
link |
00:25:12.080
I usually don't turn on artificial light
link |
00:25:14.160
because I know the sun is gonna come up eventually.
link |
00:25:16.520
But that's why I don't like the change
link |
00:25:18.920
in the timing that they do.
link |
00:25:20.520
Wait, well, what do you do between 4.30 a.m. and 7 a.m.?
link |
00:25:23.720
I mean, I look at my computer.
link |
00:25:25.520
Oh, I see.
link |
00:25:26.360
So possibly I get enough light.
link |
00:25:28.000
But in reality, I mean,
link |
00:25:30.320
as long as you let your body get the morning sunlight,
link |
00:25:33.840
which I think is really, to me,
link |
00:25:36.200
and there is no evidence, but to me,
link |
00:25:38.080
this is, if you look at all animals, plants,
link |
00:25:40.840
this morning sunlight seems to be very important.
link |
00:25:44.360
And I, you know, we don't have experiments to show it,
link |
00:25:47.400
but I have a gut feeling
link |
00:25:48.800
that it has a huge impact on humans.
link |
00:25:51.680
Well, Jamie Zeitzer's lab at the Stanford Sleep Lab
link |
00:25:54.360
has shown that these early morning light flashes
link |
00:25:57.120
can adjust the total amount of sleep
link |
00:25:59.640
that one will get, makes it easier to get into sleep.
link |
00:26:02.120
Absolutely.
link |
00:26:02.960
Okay, so.
link |
00:26:03.960
And Ken Wright also did this beautiful camping experiments
link |
00:26:08.240
that showed that.
link |
00:26:09.080
Right, maybe you should describe those
link |
00:26:10.600
because those are beautiful experiments.
link |
00:26:11.840
They are beautiful experiments.
link |
00:26:13.160
He took these, you know, college students
link |
00:26:15.900
that had the late onset of sleep and late waking time.
link |
00:26:19.640
And then he said, let's go camping
link |
00:26:21.280
and just don't use any artificial light
link |
00:26:23.760
and you could go to sleep as late or as early as you want
link |
00:26:27.760
and wake up as late as early.
link |
00:26:29.280
And he found a huge shift in their sleep pattern
link |
00:26:33.000
just by exposing them to the light-dark cycle.
link |
00:26:35.400
I mean, so.
link |
00:26:36.240
And it lasted.
link |
00:26:37.680
And it lasted.
link |
00:26:38.500
Even after they came back.
link |
00:26:39.340
Exactly.
link |
00:26:40.180
I think it was two days of camping,
link |
00:26:41.000
reset the circadian clock.
link |
00:26:41.840
Seven days, but it lasted.
link |
00:26:43.380
Yeah, it's pretty amazing.
link |
00:26:44.960
Yeah, it's really incredible.
link |
00:26:46.760
Okay, so get bright light of some sort
link |
00:26:50.800
early in the day, ideally sunlight.
link |
00:26:52.720
Even on a cloudy day,
link |
00:26:53.760
it's going to be brighter than indoor light.
link |
00:26:55.720
So that's easy.
link |
00:26:56.600
Okay, so then.
link |
00:26:57.600
And the other thing that I would like to mention to people.
link |
00:27:00.040
If you think it's very dim outside,
link |
00:27:02.400
let's say it's very cloudy, stay longer.
link |
00:27:04.560
So remember, intensity is only one component.
link |
00:27:07.300
Duration is also important
link |
00:27:08.840
because remember that the circadian system
link |
00:27:11.520
is not like the image system.
link |
00:27:12.960
In the image system, you have to change every second
link |
00:27:15.340
because you're looking at different objects.
link |
00:27:17.000
You have to change your perception.
link |
00:27:19.040
But for the circadian system,
link |
00:27:20.840
it's trying to figure out where am I
link |
00:27:23.240
in the day-night cycle.
link |
00:27:24.960
So the more you give them the information,
link |
00:27:27.040
the better you are.
link |
00:27:28.040
So if it's very bright, you don't need a lot
link |
00:27:30.560
because it's clearly going to make you fire like crazy.
link |
00:27:33.720
But if it's not bright, stay longer.
link |
00:27:35.680
Stay for one hour.
link |
00:27:37.240
Have your coffee outside or something like that.
link |
00:27:39.740
It's just going to help.
link |
00:27:41.220
I think you said something extremely important,
link |
00:27:43.080
which is that this circadian system
link |
00:27:45.260
is trying to figure out when you are in time.
link |
00:27:48.220
Not where you are in space.
link |
00:27:50.200
I said where you are in time, I meant when you are.
link |
00:27:52.540
Oh no, no, I wasn't correcting you.
link |
00:27:53.700
I just meant that, I think fundamentally,
link |
00:27:56.060
that's the incredible thing about this system,
link |
00:27:59.880
that you have this clock, this 24-hour clock in your brain,
link |
00:28:02.800
but it needs to be synchronized to the outside.
link |
00:28:05.560
So could we go a little deeper
link |
00:28:07.840
into this circadian setting behavior
link |
00:28:10.440
and come up with some general rules of thumb?
link |
00:28:13.320
So let's say it's a very bright day, extremely bright.
link |
00:28:17.260
No clouds, sun's out.
link |
00:28:20.940
You said 10 minutes, 15 minutes.
link |
00:28:22.800
And I'll tell you, if you're sensitive,
link |
00:28:25.020
you don't even have to go in the sun.
link |
00:28:26.720
You could be in the shade.
link |
00:28:28.120
There's going to be so many photons out there in the shade.
link |
00:28:31.240
It's going to be perfect.
link |
00:28:32.320
You don't even have to see the sun.
link |
00:28:34.360
You don't have to have the sun.
link |
00:28:36.120
It's great for vitamin D.
link |
00:28:37.320
That's a different story.
link |
00:28:38.280
You could do this for your skin and protect your skin.
link |
00:28:42.160
That's not my area of expertise.
link |
00:28:43.780
But for that effect on the circadian system,
link |
00:28:47.720
as long as you're outside in the shade and it's a sunny day,
link |
00:28:50.960
10 to 15 minutes should be ample amount.
link |
00:28:53.560
Okay, and then let's say it's kind of overcast.
link |
00:28:58.040
You know, it's not particularly bright
link |
00:28:59.320
or there's, you know, solid cloud cover,
link |
00:29:00.940
but, you know, obviously the sun is out,
link |
00:29:02.880
but it's not as bright.
link |
00:29:05.280
How long do you think it would take to set the clock?
link |
00:29:07.360
10 to 15 should be sufficient.
link |
00:29:09.300
Stay for half an hour, stay for 45 minutes.
link |
00:29:11.760
If it's very dark cloud, yeah, stay for longer.
link |
00:29:14.540
Okay, and if for some reason one finds themselves
link |
00:29:17.600
very far north and it's very, very dense cloud cover,
link |
00:29:22.600
how long and at what point should somebody consider
link |
00:29:26.000
using an artificial light source to mimic the sunlight?
link |
00:29:30.200
Yeah, honestly, this is where we don't have
link |
00:29:32.560
a lot of information still,
link |
00:29:34.200
because this is where we're going to discuss this
link |
00:29:36.960
maybe in more detail that if you put humans
link |
00:29:40.000
in artificial conditions,
link |
00:29:42.040
the circadian system is very sensitive to light.
link |
00:29:45.600
But in reality, in the real environment,
link |
00:29:48.840
light also is affecting other aspects
link |
00:29:51.220
that are independent of the setting
link |
00:29:53.540
of the circadian basemaker.
link |
00:29:55.280
Okay.
link |
00:29:56.120
And these which we call the direct effect of light
link |
00:29:58.000
on mood, for example.
link |
00:29:59.960
So that is very hard to figure out
link |
00:30:02.160
what intensity you need to use,
link |
00:30:03.760
and we haven't done enough experiments,
link |
00:30:05.320
because the system has been discovered just recently.
link |
00:30:07.920
But I would say if you use bright light in the morning,
link |
00:30:11.980
and I mean, it's hard for me to give numbers,
link |
00:30:14.580
it can get complicated.
link |
00:30:18.060
But yeah, I mean, if you're,
link |
00:30:19.620
honestly if you're that far north
link |
00:30:21.460
and you're in the winter and you want to get,
link |
00:30:23.220
make sure you don't use these light boxes,
link |
00:30:25.580
I would suggest that personally, but that's it.
link |
00:30:28.740
I use, it's actually not designed for circadian setting,
link |
00:30:31.700
but I have a 930 lux light pad that I bought,
link |
00:30:35.940
and I bought it, they're very affordable
link |
00:30:38.060
compared to the Dawn simulating lights,
link |
00:30:40.860
which are quite expensive, frankly.
link |
00:30:43.460
And I put it there, and so I just basically,
link |
00:30:45.960
when I wake up in the morning,
link |
00:30:47.020
I use that until the sun comes out,
link |
00:30:48.900
and then I make sure once the sun is out, I go outside.
link |
00:30:51.180
But I keep that thing on all day.
link |
00:30:53.280
And I don't know if that's good or bad.
link |
00:30:55.100
Is it good or bad?
link |
00:30:56.100
I honestly, I don't think being exposed to bright light
link |
00:30:59.340
in the day is going to ever be bad,
link |
00:31:00.820
because really, if you're outside in the day,
link |
00:31:03.740
unless, you know, the worst is gonna happen
link |
00:31:06.100
if the temperature is very high,
link |
00:31:07.660
your body's gonna say don't dehydrate and go to sleep.
link |
00:31:10.340
So you could tell actually sometimes when it's very hot,
link |
00:31:13.940
the more you get exposed to bright light,
link |
00:31:15.820
the sleepier you feel in the afternoon,
link |
00:31:17.780
which is counterintuitive.
link |
00:31:20.180
So, but.
link |
00:31:21.020
And that's to protect us, you think, against dehydration?
link |
00:31:23.340
I think if you think about the human evolution
link |
00:31:26.020
from near the equator in the,
link |
00:31:28.420
between noon and a certain time in the afternoon,
link |
00:31:31.620
it would have been very hard for you to maintain
link |
00:31:34.600
physiological homeostatic function,
link |
00:31:36.620
being active at this very high temperature time.
link |
00:31:39.700
So I think napping was a way,
link |
00:31:42.060
that's why I think it has a major function,
link |
00:31:44.060
which is still, napping was a way to somehow
link |
00:31:47.100
take you away from that dangerous zone.
link |
00:31:49.180
And maybe that's why people in the north,
link |
00:31:51.820
they say in the winter, we can't wake up in the morning
link |
00:31:54.100
because they don't have this long light,
link |
00:31:55.680
so they sleep it more at night.
link |
00:31:57.280
But in the summer, they say we feel like we can't go to sleep
link |
00:32:00.320
we have to put all these dark curtains.
link |
00:32:02.940
So I think, you know, venturing that much north,
link |
00:32:06.940
up north, has been, came up with problem
link |
00:32:09.820
because evolution was used to a certain light environment
link |
00:32:13.100
that was completely changed with a human,
link |
00:32:16.380
with other animals, I think, that lived there longer.
link |
00:32:20.220
They have come up with very interesting adaptation
link |
00:32:22.740
of actually measuring even very small changes
link |
00:32:26.180
in the light, in the light intensities that still occur.
link |
00:32:29.060
So even if you're near the poles,
link |
00:32:32.260
even though it's always light,
link |
00:32:33.900
but there is a change in the light intensity
link |
00:32:36.020
across the day and night cycle.
link |
00:32:37.180
So your system, if it's linear,
link |
00:32:39.020
and remember I told you that IP RGCs are incredibly linear,
link |
00:32:42.820
can still measure, oh, this is lower light than higher light
link |
00:32:46.460
if the organism has the ability to do that.
link |
00:32:49.740
I see, you know, it's interesting,
link |
00:32:51.200
I've spent so much time learning from you,
link |
00:32:54.520
fortunately, about these cells,
link |
00:32:56.580
and yet I never really appreciated until now how,
link |
00:33:00.020
on the one hand, they are tracking the amount of light
link |
00:33:03.160
to understand when we are in time
link |
00:33:05.420
relative to the 24-hour cycle,
link |
00:33:07.820
but also that you keep mentioning
link |
00:33:09.860
this linear measurement of intensity,
link |
00:33:11.860
that they really are trying to figure out
link |
00:33:13.860
when we are in time by measuring the intensity of light.
link |
00:33:16.500
And of course, the sun is the most intense source
link |
00:33:18.900
of light available to us.
link |
00:33:21.020
So, okay, so I think we've nailed down
link |
00:33:24.180
that first part of the day.
link |
00:33:25.900
Basically, it's get 10 to 30 minutes,
link |
00:33:27.600
depending on how bright it is,
link |
00:33:29.000
and try and do that as often as possible
link |
00:33:31.420
to give the system a regular-
link |
00:33:32.580
Daily is the best.
link |
00:33:33.420
This system is really about,
link |
00:33:35.820
and you'll see that even for the effect on depression,
link |
00:33:38.460
it's about multiple days.
link |
00:33:40.580
So you don't have to worry if you missed it one day,
link |
00:33:43.280
you know, stay longer if you want,
link |
00:33:45.140
but if you're in a hurry and you want to do other stuff,
link |
00:33:48.140
that's a great recommendation.
link |
00:33:49.980
So you might want to compensate with some extra time
link |
00:33:51.980
if you missed a day or two.
link |
00:33:53.740
And this is why I've heard you say before,
link |
00:33:55.900
it's entirely possible to get severely jet-lagged
link |
00:33:58.940
without traveling.
link |
00:33:59.880
Absolutely.
link |
00:34:00.720
Simply by staying in, being on your phone too much,
link |
00:34:02.980
not getting the sunlight.
link |
00:34:03.980
And you saw this during the pandemic.
link |
00:34:06.060
A lot of people mentioned
link |
00:34:07.380
that their sleep-wake cycles suffered a lot.
link |
00:34:10.740
Because if you're not going out,
link |
00:34:12.980
and if you're staying at home,
link |
00:34:14.500
and you don't have big windows,
link |
00:34:16.380
and you're waking late, waking up late,
link |
00:34:18.740
and then you're using very bright light till late at night,
link |
00:34:21.540
your body's going to shift.
link |
00:34:23.180
And now your day is going to start instead of,
link |
00:34:26.060
like really when the sun comes up,
link |
00:34:27.580
let's say at six o'clock in the morning,
link |
00:34:29.320
it's going to,
link |
00:34:30.160
your day is going to start at 11 o'clock in the morning.
link |
00:34:32.060
That's what your body's going to think
link |
00:34:33.660
is the beginning of the day.
link |
00:34:35.780
So then you're not going to be able to sleep
link |
00:34:38.340
at 10 o'clock at night,
link |
00:34:39.700
because now that's really for your body
link |
00:34:43.340
is completely different timing.
link |
00:34:45.340
And you could see this happen during the pandemic
link |
00:34:48.020
at a very high scale.
link |
00:34:49.500
People get delayed in their sleep-wake cycle a lot.
link |
00:34:52.680
And there is this idea of chronotypes
link |
00:34:54.900
that we all each intrinsically have a best rhythm
link |
00:34:59.100
of either being a morning person,
link |
00:35:00.940
you called yourself an early person,
link |
00:35:02.540
or a night owl,
link |
00:35:03.740
or more of a kind of standard,
link |
00:35:05.820
to bed around 10, 30, up around seven type thing.
link |
00:35:08.920
And I think there are now good data,
link |
00:35:11.260
correct me if I'm wrong,
link |
00:35:12.740
from the National Institutes of Mental Health and elsewhere,
link |
00:35:15.060
showing that the more we deviate from that intrinsic rhythm,
link |
00:35:19.100
the more mental health issues
link |
00:35:21.220
and physical health issues start to crop up.
link |
00:35:23.100
So there is great data on this,
link |
00:35:24.900
and there is a couple of things that complicate this.
link |
00:35:27.100
The first is the people who usually are late,
link |
00:35:30.460
they tell you that the society doesn't accommodate.
link |
00:35:32.940
What, by late, what do you mean?
link |
00:35:34.900
People that wake up late and go to sleep late?
link |
00:35:36.540
Go to sleep late and wake up late.
link |
00:35:38.580
They have an overwhelmingly higher level of depression
link |
00:35:42.060
and failures.
link |
00:35:43.460
I mean, clearly, I mean,
link |
00:35:44.660
the reason that people say sleep early, wake up early,
link |
00:35:48.820
you're better,
link |
00:35:49.660
because human notice that people who wake up,
link |
00:35:52.540
go to sleep early and wake up early,
link |
00:35:54.300
they do better in life.
link |
00:35:55.460
They notice that.
link |
00:35:56.300
They just perform better.
link |
00:35:57.340
They perform.
link |
00:35:58.180
But the question is, is that intrinsic to the system,
link |
00:36:01.380
or is that society?
link |
00:36:02.460
Because society start things usually early or late.
link |
00:36:05.080
That's a hard question to ask.
link |
00:36:05.920
We discriminate against late risers.
link |
00:36:07.940
In a way, we discriminate, right?
link |
00:36:09.640
But the other explanation is Ken Wright's experiment.
link |
00:36:12.940
These late riser,
link |
00:36:14.700
if they were truly chronotypically late,
link |
00:36:18.140
why would they shift so easily when you put them in the,
link |
00:36:21.720
if you were really chronotypically late,
link |
00:36:23.940
and there is a phase relation
link |
00:36:25.820
between the light-dark environment
link |
00:36:27.300
and your circadian clock,
link |
00:36:28.820
then doing this camping experiment
link |
00:36:30.580
should not have caused much changes,
link |
00:36:32.460
because it's not that light is gonna affect you
link |
00:36:37.260
in a certain way.
link |
00:36:38.100
It's that this is the relationship that your body decided,
link |
00:36:40.820
that I'm a late sleeper, late waking.
link |
00:36:43.820
So, honestly, I'm still unable to figure out
link |
00:36:48.120
how much of this late waking up
link |
00:36:50.300
is controlled by the light environment,
link |
00:36:52.580
and how much is intrinsic.
link |
00:36:53.820
I'm sure there are differences.
link |
00:36:55.840
But are they as big as we see in the environment?
link |
00:36:58.540
Because you have people that go up to sleep at 7 p.m.
link |
00:37:02.800
and wake up at 1 a.m.
link |
00:37:04.140
These are clearly advanced phase.
link |
00:37:06.220
So people that go to sleep at 7 p.m.
link |
00:37:08.020
and wake up at 1 a.m.
link |
00:37:09.380
and feel good doing that.
link |
00:37:11.060
I'm not so sure they feel good,
link |
00:37:12.740
but a lot of the time you talk to people,
link |
00:37:14.800
they say they are high achievers,
link |
00:37:17.060
but they suffer because they go to 7 p.m.,
link |
00:37:20.300
wake up advanced phase sleep syndrome,
link |
00:37:22.540
they call it, they call it a syndrome.
link |
00:37:25.380
But then you have people who would not be able
link |
00:37:28.300
to sleep till 5 a.m.
link |
00:37:29.780
and not be able to wake up till 3 p.m., right?
link |
00:37:33.580
And I'm not so sure that the circadian system
link |
00:37:35.880
is that variable in the human population.
link |
00:37:38.100
I mean, clearly there are maybe some genetic factors
link |
00:37:40.740
that make a small percentage of everything
link |
00:37:43.820
with a bell shape.
link |
00:37:45.420
But I think most of the time,
link |
00:37:47.120
the light environment may play a role.
link |
00:37:49.100
And once, as we've talked about,
link |
00:37:51.460
this is a long-term effect of light.
link |
00:37:53.800
Once you get into a rhythm,
link |
00:37:55.900
and I don't mean it as a pun in reality,
link |
00:37:58.060
once you get into a rhythm,
link |
00:37:59.400
it's hard to break out of that rhythm.
link |
00:38:01.800
Because if you start sleeping late and waking up late,
link |
00:38:04.780
you're not getting the morning sunlight.
link |
00:38:06.740
Right.
link |
00:38:07.580
And so you're just gonna be late.
link |
00:38:09.620
And if you're like me, waking up early,
link |
00:38:11.940
you're getting the morning sunlight.
link |
00:38:13.300
You're getting what Zeisler said, I said his last name wrong,
link |
00:38:19.420
the one in Stanford who did the-
link |
00:38:21.020
Oh, Jamie Zeisler.
link |
00:38:22.180
Zeisler, yeah.
link |
00:38:23.540
He actually worked for Zeisler, so Zeisler and Zeisler.
link |
00:38:27.420
Yeah, there are a lot of Zs and Is in their names.
link |
00:38:30.600
Both phenomenal scientists.
link |
00:38:32.260
Well, what it seems to me is the case
link |
00:38:35.700
is that the only way to really know
link |
00:38:38.280
if you're meant to be an early bird, as they call it,
link |
00:38:41.460
an early person or a late person,
link |
00:38:43.500
or somewhere in between, is to get morning sunlight
link |
00:38:46.220
and figure out whether or not that makes you feel better.
link |
00:38:48.260
And to understand, to be educated
link |
00:38:52.500
about how to measure intensity,
link |
00:38:54.780
how to measure, I put it between quotation,
link |
00:38:57.180
because you either get a measuring device,
link |
00:38:59.740
but you cannot depend on your eye to measure intensity.
link |
00:39:03.560
Okay, so how do we do that?
link |
00:39:04.500
Because you keep coming back to this,
link |
00:39:06.120
so that tells me that it's important.
link |
00:39:08.020
It's very important.
link |
00:39:08.860
So there are apps, like free apps, like Light Meter,
link |
00:39:12.820
where you can walk around and hold the button down
link |
00:39:14.560
and see how many lux are in the environment.
link |
00:39:17.860
These are complicated because you have to point them
link |
00:39:20.060
to specific regions.
link |
00:39:21.540
So how do people start to develop an intuitive sense
link |
00:39:25.080
of the measurement of intensity?
link |
00:39:27.260
Yeah, I think at one point I posted on Instagram
link |
00:39:30.900
how I keep my nighttime at home.
link |
00:39:33.540
And I found out that my night vision is very strong.
link |
00:39:36.920
So I found out that I, especially in the winter,
link |
00:39:39.620
I only need candle light.
link |
00:39:41.180
So I literally use these tea lights,
link |
00:39:43.620
and I put like 15 or 20 of them.
link |
00:39:45.820
How romantic.
link |
00:39:46.700
And it's so nice.
link |
00:39:47.760
I could see it clearly doesn't affect my circadian system.
link |
00:39:51.140
You and your cats.
link |
00:39:52.180
And my wife.
link |
00:39:53.220
And your wife, of course.
link |
00:39:54.060
It's just great, it's just great, right?
link |
00:39:55.800
But I don't expect people
link |
00:39:56.980
to have the same night vision as me.
link |
00:39:59.380
So the simple, I mean, I tell people, do the experiment.
link |
00:40:03.020
So if you put three or four lights in your room,
link |
00:40:07.220
switch to, sit for 15 minutes, switch two off.
link |
00:40:10.440
Switch two off.
link |
00:40:11.280
Let's say you're using five.
link |
00:40:12.740
And see, after 15 minutes,
link |
00:40:14.580
you will not recognize you switched these two off.
link |
00:40:17.340
My gut feeling is that most people would need
link |
00:40:19.820
at least 10 times less light than they use at night to see.
link |
00:40:24.000
The problem people use it,
link |
00:40:25.500
because most of the time they didn't see
link |
00:40:27.380
the morning sunlight.
link |
00:40:28.260
They are actually hungry for light without their knowledge.
link |
00:40:31.060
So they come switch all these lights on,
link |
00:40:33.020
but at the wrong time, because they woke up late.
link |
00:40:36.180
Okay, now I understand.
link |
00:40:37.820
So this morning light viewing goes way beyond
link |
00:40:41.280
setting your clock.
link |
00:40:42.940
It's also a way to determine
link |
00:40:44.740
how little light you need later in the day.
link |
00:40:48.120
And we're going to talk about this in a moment,
link |
00:40:50.120
but how little light you get later in the day
link |
00:40:53.220
is a very strong determinant of things
link |
00:40:55.040
like when you will wake up,
link |
00:40:56.080
whether or not you wake up feeling refreshed, et cetera.
link |
00:40:58.380
Let's-
link |
00:40:59.220
And that's why.
link |
00:41:00.260
Yeah.
link |
00:41:01.100
I'm going to break it on your show, Andrew,
link |
00:41:02.860
that I'm going to tell you,
link |
00:41:04.020
I think there is something else
link |
00:41:06.020
that people need to think about,
link |
00:41:07.340
which is the tripartite model.
link |
00:41:09.540
That this model incorporate three components
link |
00:41:12.340
we should talk about in details
link |
00:41:13.860
that allows us humans and all animals
link |
00:41:17.780
to incorporate the circadian clock
link |
00:41:20.360
and its relation to light,
link |
00:41:22.020
the homeostatic drive,
link |
00:41:24.040
and the direct effect of the environment,
link |
00:41:26.140
which includes stress, light, all kinds of stuff.
link |
00:41:29.180
They have to be incorporated together.
link |
00:41:31.320
If you think, that's what I think right now,
link |
00:41:33.540
if you think of one alone,
link |
00:41:35.480
you will always miss something.
link |
00:41:37.700
And when you think of them as a whole,
link |
00:41:39.940
things really become clear.
link |
00:41:41.480
It's actually quite amazing.
link |
00:41:43.020
Okay, well, we will definitely want to hear
link |
00:41:45.540
about your tripartite theory
link |
00:41:47.380
and go into detail about this homeostatic mechanisms.
link |
00:41:50.620
I want to make sure that for people who are thinking now,
link |
00:41:53.980
I'm sure, about light and how it impacts them.
link |
00:41:56.860
So the morning light viewing behavior,
link |
00:41:58.940
I like to think we've tacked down clearly.
link |
00:42:01.160
And thank you for that
link |
00:42:02.160
because there's so much information out there
link |
00:42:03.920
and I've tried to relay that information.
link |
00:42:06.020
Of course, you're my primary source
link |
00:42:07.260
for all things circadian,
link |
00:42:09.500
as well as Jamie and others, of course, Matt Walker.
link |
00:42:12.020
But I think you've made that very, very clear.
link |
00:42:15.940
Now, let's say I've gotten my morning sunlight, okay?
link |
00:42:20.460
Made my bright artificial light.
link |
00:42:21.620
And throughout the day, you said to get a lot of light.
link |
00:42:23.860
So I'm working at my desk.
link |
00:42:25.020
Maybe I'll go out during the day a few times,
link |
00:42:27.860
but I'm working at my computer, I'm doing things.
link |
00:42:30.500
Is there anything about light viewing
link |
00:42:32.100
in the middle of the day that people should keep in mind?
link |
00:42:35.540
Or can they just sort of freestyle it,
link |
00:42:37.660
depending on what they're doing?
link |
00:42:38.540
Most people are not in a dark room throughout the day.
link |
00:42:42.580
My gut feeling, if you got your morning sunlight,
link |
00:42:45.540
you walk from your car slowly or you walk to work,
link |
00:42:49.700
you didn't wear sunglasses
link |
00:42:50.860
when the lights were still dim in the morning,
link |
00:42:53.380
that you could freestyle it.
link |
00:42:55.000
That even if you don't get a lot of light,
link |
00:42:57.700
there is a way to just, you know, in the day,
link |
00:43:01.060
you don't have to just worry
link |
00:43:02.340
about getting a lot of bright light.
link |
00:43:03.820
But personally, I like to do that.
link |
00:43:05.820
So I go out at lunch and have my lunch outside as well.
link |
00:43:09.660
This reminds the body that here it is even brighter now.
link |
00:43:13.540
But the evidence is that you could literally
link |
00:43:16.620
help your circadian clock by giving lights at dawn and dusk.
link |
00:43:20.380
But again, if you think of the tripartite model,
link |
00:43:22.860
this may be important versus circadian clock,
link |
00:43:25.060
but is it important for your mood?
link |
00:43:27.900
So that's where I think you need, or the homeostatic drive.
link |
00:43:31.260
So that's where you need to think about it.
link |
00:43:33.620
So for the clock, for entraining your clock,
link |
00:43:36.780
you literally can entrain it only by the dawn sunlight.
link |
00:43:39.820
You actually don't need dawn and dusk.
link |
00:43:41.580
You can even forget that.
link |
00:43:42.820
Yeah, and I appreciate that you're distinguishing
link |
00:43:44.840
between circadian effects and other effects of light.
link |
00:43:47.660
You're being very precise, which is appreciated.
link |
00:43:51.580
Until we hear about this tripartite model,
link |
00:43:53.660
which we will cover, for the sake of the discussion,
link |
00:43:57.320
let's treat the light viewing behavior
link |
00:43:59.580
as what are the benefits or drawbacks of viewing light
link |
00:44:04.260
for all biological purposes, not just circadian settings.
link |
00:44:07.380
So in the morning, it's clearly going to set the clock.
link |
00:44:10.820
And then during the day, if I understand correctly,
link |
00:44:13.820
the idea is to get as much bright light as you can
link |
00:44:15.860
because you're feeding, it sounds like,
link |
00:44:17.280
a sort of light hunger.
link |
00:44:19.820
Exactly.
link |
00:44:20.660
I see.
link |
00:44:21.500
I love this way to put it.
link |
00:44:22.320
I think there is a weird light hunger.
link |
00:44:24.260
Considering that we're not photosynthetic organisms,
link |
00:44:27.700
there is a weird light hunger in animals
link |
00:44:29.880
that they need to measure, they need measure.
link |
00:44:33.180
And I think that relates to the season
link |
00:44:35.140
because the whole reproduction cycle of animals
link |
00:44:38.220
is gonna depend on the availability of food
link |
00:44:41.700
in the environment.
link |
00:44:42.640
And if you don't know when the season's gonna happen,
link |
00:44:45.300
they don't have calendars,
link |
00:44:47.040
it's gonna be very hard to survive.
link |
00:44:48.740
So I think that's why we have this light hunger.
link |
00:44:51.100
That's a major hypothesis.
link |
00:44:52.700
It's not been tested.
link |
00:44:54.020
Interesting.
link |
00:44:54.860
So then afternoon and evening start to approach.
link |
00:44:59.100
So I've had this weird experience.
link |
00:45:00.780
Maybe you can psychologically
link |
00:45:02.820
or biologically diagnose me now, Sameer.
link |
00:45:05.260
So where if I go into a movie in the afternoon,
link |
00:45:07.840
like a matinee, and I come out and it's dark,
link |
00:45:11.540
I notice a significant drop in my mood
link |
00:45:15.180
and my ability to go to sleep.
link |
00:45:17.840
Whereas if I get some view of the light in the evening,
link |
00:45:21.460
it doesn't have to be the sunset,
link |
00:45:22.700
although sunsets are nice,
link |
00:45:23.900
but I get some light pulse in the afternoon
link |
00:45:26.780
that I have no trouble whatsoever.
link |
00:45:29.180
And this happens in a daily, on a single time to watch?
link |
00:45:32.980
More or less.
link |
00:45:34.700
That's interesting.
link |
00:45:35.520
And then you mentioned the camping experiment
link |
00:45:37.260
where when they went camping,
link |
00:45:38.400
they're seeing the sunrise and the sunset.
link |
00:45:41.140
So what should people do in the afternoon slash evening time
link |
00:45:46.140
in terms of their light viewing behavior?
link |
00:45:48.180
I mean, the best thing to do
link |
00:45:49.580
is to let the natural light creep in into darkness, right?
link |
00:45:53.100
That would be the best.
link |
00:45:54.680
But clearly that would be inefficient.
link |
00:45:57.060
You wanna go home, you wanna read,
link |
00:45:59.740
you wanna talk to your kids,
link |
00:46:01.720
you wanna talk to your family.
link |
00:46:03.400
So I think, you know, it's nice to extend the day.
link |
00:46:06.000
I don't think that's wrong.
link |
00:46:07.140
If you somehow can block that light
link |
00:46:10.220
from affecting your circadian clock.
link |
00:46:12.100
So should people use blue blockers in the evening?
link |
00:46:15.420
I personally do not like any blockers
link |
00:46:19.020
that take a single wavelength of light.
link |
00:46:20.980
Because again, if you think of a holistic approach,
link |
00:46:24.220
yes, the blue blocker is gonna prevent you
link |
00:46:26.180
from affecting your circadian clock very much,
link |
00:46:29.580
but then your vision is gonna be distorted
link |
00:46:31.720
because we always see in full spectrum.
link |
00:46:34.220
The sun has this beautiful spectrum, right?
link |
00:46:36.860
And then when you start seeing without the blue,
link |
00:46:40.420
things look yellow and it can get really weird, right?
link |
00:46:43.740
I mean, so I personally,
link |
00:46:46.380
I've tried the blue blocker and I couldn't even wear them.
link |
00:46:49.420
I thought they were just really horrendous, to be honest.
link |
00:46:52.980
Well, along the lines of blue blockers,
link |
00:46:54.940
I think a lot of people mistakenly wear them all day long.
link |
00:46:58.340
Oh my God, that would be very bad.
link |
00:46:59.660
A lot of people do that.
link |
00:47:01.260
A lot of people do that.
link |
00:47:02.180
They think that the blue light is bad.
link |
00:47:04.060
I think that the concept of blue light being bad
link |
00:47:07.940
led to a lot of product development.
link |
00:47:10.380
And a lot of people are just assuming
link |
00:47:11.900
that viewing blue light is what was giving them headaches
link |
00:47:14.580
when, in fact, it might have just been looking
link |
00:47:16.060
at screens at close distance.
link |
00:47:17.940
So here's the problem, right?
link |
00:47:19.460
I mean, the blue light got the bad reputation
link |
00:47:22.060
because people who gave a pure blue light
link |
00:47:24.100
showed that it caused a huge retinal damage.
link |
00:47:26.980
But again, if you're using blue light in its pure form,
link |
00:47:30.420
it has a lot of energy because it's shorter wavelength.
link |
00:47:33.620
But we're talking about full spectrum light.
link |
00:47:36.380
There are ways now where you could change the spectrum
link |
00:47:39.700
of the light and keep it white between day and night
link |
00:47:43.300
and change the content of the color without you noticing.
link |
00:47:47.580
So you don't even have to affect your vision.
link |
00:47:49.780
So how would you go about doing that?
link |
00:47:51.500
So you just lower the level of the blue light.
link |
00:47:53.780
You don't have to eliminate it.
link |
00:47:54.940
So just dim the lights.
link |
00:47:56.260
Dim the blue, then increase the yellow,
link |
00:47:59.220
but keep all the colors in a certain white
link |
00:48:02.860
so you could have different warmness of white.
link |
00:48:06.820
And people know how to do this.
link |
00:48:08.260
Physicists know how to do this.
link |
00:48:09.660
People who work with light know how to do this.
link |
00:48:11.580
Well, maybe somebody in the wellness slash,
link |
00:48:14.260
I don't like the word,
link |
00:48:15.100
but biohacking or optical community will do this.
link |
00:48:18.620
I think it's really important.
link |
00:48:20.140
I see so many people wearing blue lockers.
link |
00:48:22.380
I don't know why they love blue.
link |
00:48:24.020
Well, I think they're just uninformed.
link |
00:48:25.180
I think, frankly-
link |
00:48:26.020
And to be honest, it's easy, right?
link |
00:48:27.860
It's easier to explain to somebody,
link |
00:48:30.100
if IPRCCs respond mostly to blue,
link |
00:48:32.540
remove blue, you'll be fine, right?
link |
00:48:34.700
But that's not as simple as that
link |
00:48:36.260
because they also receive road and cone input.
link |
00:48:38.340
So you want to actually,
link |
00:48:39.980
and we could go into details
link |
00:48:41.860
that's boring for you listeners,
link |
00:48:43.300
but it also affect the adaptation properties
link |
00:48:45.740
of the whole retina.
link |
00:48:47.140
So you don't want to do something so drastic
link |
00:48:49.580
that you take just one color of the spectrum.
link |
00:48:51.820
It just seems very counterintuitive to me, to be honest.
link |
00:48:56.500
You've told me before as well
link |
00:48:58.620
that just because these intrinsically photosensitive
link |
00:49:02.380
circadian setting ganglion cells
link |
00:49:05.220
respond best to blue light,
link |
00:49:07.180
if the light is bright enough,
link |
00:49:08.780
because they also get input from other components of the eye,
link |
00:49:12.380
it doesn't matter if you block the blues.
link |
00:49:14.940
If you're looking at bright light at night,
link |
00:49:16.500
you're going to disrupt your circadian cycle.
link |
00:49:18.500
And that's why I didn't want to go into the boring details,
link |
00:49:20.860
but themselves, the photoreceptors
link |
00:49:22.660
have a wide range of responsiveness.
link |
00:49:25.300
So they are most sensitive to blue light,
link |
00:49:27.340
but that doesn't mean they don't respond to green light
link |
00:49:30.260
or to shorter than blue light.
link |
00:49:32.180
They respond to very, very wide spectrum
link |
00:49:35.300
with different sensitivities.
link |
00:49:36.980
So unless you understand the system, just removing 480,
link |
00:49:40.660
I don't think it's going to do anything.
link |
00:49:41.660
480 nanometers, yeah.
link |
00:49:43.460
So your home is a cave at night, basically.
link |
00:49:48.540
It's a nice cave.
link |
00:49:49.740
It's a nice cave with candles, right?
link |
00:49:52.340
And you and your cats and your lovely wife,
link |
00:49:56.140
who I know who's also a phenomenal scientist
link |
00:49:58.260
in her own right.
link |
00:49:59.100
Thank you, yeah, she is.
link |
00:49:59.940
She is.
link |
00:50:01.860
But you do keep your home quite dim to dark at night.
link |
00:50:06.140
In fact, I did go to meetings with some of my friends
link |
00:50:10.100
who work on this and they really struggled with me.
link |
00:50:12.300
They said we could have broken our legs
link |
00:50:14.580
living in the same light environment that you do.
link |
00:50:16.980
So I am an extreme, but I measured it for myself
link |
00:50:20.460
and I asked Reiji, my wife, if she's okay with it.
link |
00:50:22.900
She also liked the dimness.
link |
00:50:24.220
Both of us can see well in dim conditions
link |
00:50:27.140
and that helps us a lot.
link |
00:50:30.540
But I think you have to measure it for yourself.
link |
00:50:32.740
You really have to do, it's a very simple experiment.
link |
00:50:36.460
Just try to dim the light as much as you can.
link |
00:50:38.980
I call it the minimum amount of light
link |
00:50:41.540
you require to see comfortably.
link |
00:50:44.260
And that's how you want your environment ideally at night.
link |
00:50:47.140
This is what I think is the game changer.
link |
00:50:49.940
If you reach to a level where it's just barely,
link |
00:50:53.380
you're literally on the cusp of seeing uncomfortably
link |
00:50:56.580
versus seeing very comfortably,
link |
00:50:58.780
you are gonna be very much better
link |
00:51:01.540
than I don't like to make it completely dark.
link |
00:51:04.260
I think complete darkness induce anxiety in humans,
link |
00:51:08.140
to be honest, so I don't like complete darkness.
link |
00:51:11.820
In fact-
link |
00:51:12.660
Kids don't like complete darkness.
link |
00:51:13.500
They like night light.
link |
00:51:14.860
Even nocturnal animals don't like complete darkness.
link |
00:51:17.540
I mean, we have studies in animals that are nocturnal
link |
00:51:21.020
that if you put them in complete darkness
link |
00:51:22.580
for several weeks, they have severe anxiety
link |
00:51:26.460
and depression-like effect.
link |
00:51:28.260
So keep the light dim.
link |
00:51:30.060
You know, use red light that is very dim
link |
00:51:33.980
if you wanna keep the room for sleeping.
link |
00:51:36.740
Red light that is very dim has very small effect
link |
00:51:40.260
on circadian clock.
link |
00:51:43.180
And below 10 lux of red light
link |
00:51:44.940
literally doesn't affect sleep at all.
link |
00:51:47.420
So there are ways to do it.
link |
00:51:49.300
It's just we need to educate the public.
link |
00:51:51.220
And I feel like you literally need a whole lecture
link |
00:51:55.580
to just explain to the people how to deal with light
link |
00:51:58.700
because it's not as simple as people think.
link |
00:52:01.060
Well, that's what we're doing here.
link |
00:52:02.260
We're stepping through it piece by piece.
link |
00:52:03.980
And the reason we're doing that
link |
00:52:06.420
is because it's not as simple as saying
link |
00:52:08.140
just block blue light or get a lot of light during the day.
link |
00:52:10.580
I mean, just put it in perspective to tell it,
link |
00:52:13.420
we only have three different cones in our retina
link |
00:52:17.220
that respond to three different colors.
link |
00:52:20.020
We call them red cones for simplicity,
link |
00:52:23.100
green cones and blue cones.
link |
00:52:25.260
Yet we have only three of these,
link |
00:52:27.100
but we could see massive palette of colors.
link |
00:52:30.620
So that tells you something.
link |
00:52:32.300
If the system was just simply about a single color
link |
00:52:35.780
and it's just removing 480 or just blue is sufficient,
link |
00:52:39.900
then we should only see in red, yellow and blue.
link |
00:52:42.420
We shouldn't see all these different hues of color.
link |
00:52:45.100
But because the system is not that,
link |
00:52:47.140
we see all these different colors.
link |
00:52:49.700
And that's why it's important to remind people
link |
00:52:51.940
that the white light is made of many different colors.
link |
00:52:55.500
It's actually like the rainbow.
link |
00:52:56.940
That's why you see the rainbow.
link |
00:52:58.020
It's made of many colors.
link |
00:52:59.660
White light is never truly white.
link |
00:53:01.620
It's made of lot of different colors.
link |
00:53:03.820
It's like the Pink Floyd album cover.
link |
00:53:05.420
Exactly, exactly, exactly.
link |
00:53:09.500
So dim at night, maybe dim red light ideally,
link |
00:53:12.980
or candlelight, find that minimum required light level.
link |
00:53:17.380
Just make sure when you lower the light,
link |
00:53:19.340
sit for at least 10 to 15 minutes.
link |
00:53:21.660
Let your system adapt.
link |
00:53:23.700
Because if you had it bright light and you switch it off,
link |
00:53:26.660
surely you're gonna suffer
link |
00:53:27.860
because your system didn't adapt it.
link |
00:53:29.460
It was used to very bright light.
link |
00:53:31.900
So you want to engage your rods,
link |
00:53:33.820
which take a long time to dark adapt.
link |
00:53:36.780
So that's why I tell you, just wait a little bit.
link |
00:53:39.620
Don't just switch it off, I don't see, put it on.
link |
00:53:42.380
Put it off, sit down, wait for 10 minutes,
link |
00:53:44.740
ideally 15 minutes, and then see how you see.
link |
00:53:48.580
And then once you do that,
link |
00:53:50.300
you will notice that actually,
link |
00:53:51.940
yeah, I could see quite well, even with much less light.
link |
00:53:57.580
What do you do regarding screens?
link |
00:54:00.420
Yeah, that's the hardest thing.
link |
00:54:02.500
Again, I mean, there are beautiful programs
link |
00:54:05.340
that change the whole intensity and color of the screen.
link |
00:54:08.740
These could help dim your screen at night
link |
00:54:11.060
to the lowest part.
link |
00:54:11.980
I mean, yes, you won't see it
link |
00:54:13.500
when you wake up in the morning,
link |
00:54:14.580
but then you can increase the intensity.
link |
00:54:16.820
So try to decrease.
link |
00:54:18.220
I mean, just what we were talking about.
link |
00:54:20.740
Think of light intensity, duration, color, and time of day.
link |
00:54:25.180
You really have to keep these four things together, right?
link |
00:54:28.780
We've roomed together at a couple of meetings
link |
00:54:31.220
from time to time, no longer,
link |
00:54:32.660
because one of us, not to be named,
link |
00:54:34.700
has a severe snoring issue
link |
00:54:36.780
that made the other one pseudo homicidal.
link |
00:54:41.260
You can guess who that was.
link |
00:54:44.340
But I've seen you check your phone after dark once or twice,
link |
00:54:49.340
and you did it by pointing your phone away from you, right?
link |
00:54:54.460
And actually I'm sort of half joking,
link |
00:54:56.900
and you dim it quite a bit.
link |
00:54:58.940
I'm sort of half joking,
link |
00:54:59.940
but it actually makes sense
link |
00:55:01.380
that if you shine a flashlight in your eye,
link |
00:55:03.300
it's much brighter than if you shine a flashlight.
link |
00:55:05.140
So if you just look on the side,
link |
00:55:07.660
most of the light is going to go this way,
link |
00:55:09.340
and you're only seeing this way.
link |
00:55:11.140
Okay, and as silly as that might seem to people listening,
link |
00:55:14.060
I mean, what it means is that
link |
00:55:15.820
getting bright light in your eyes at night
link |
00:55:18.260
is something that you really want to avoid,
link |
00:55:21.020
but there is the reality then.
link |
00:55:22.980
And even when I check sometimes,
link |
00:55:24.620
if I have something and I check it so fast
link |
00:55:28.180
and switch it off so fast,
link |
00:55:29.260
so I'm also aware of the duration.
link |
00:55:31.500
I'm also aware of the duration, right?
link |
00:55:34.740
So duration, intensity, color, and time of day.
link |
00:55:38.220
Ideally, I should not check iPhones and iPads.
link |
00:55:41.140
I don't use iPad at night
link |
00:55:42.580
because it's hard to lower it enough,
link |
00:55:44.940
because it's huge.
link |
00:55:46.420
But even my iPhone, I try not to use it at night.
link |
00:55:49.460
And like, once it becomes 8.30 or 9,
link |
00:55:52.420
I don't look at it at all.
link |
00:55:53.700
Unless it's World Cup or Euro Cup,
link |
00:55:55.540
in which case, Sandra's on 24 hours, everybody.
link |
00:55:57.940
That's only every four years.
link |
00:55:59.740
He's a big soccer fan.
link |
00:56:02.180
All right, this has been incredibly, no pun, illuminating.
link |
00:56:07.740
Let's talk about the relationship between light
link |
00:56:10.420
and some of these other non-circadian
link |
00:56:13.580
or pseudo-circadian effects.
link |
00:56:15.860
And we will try and link those.
link |
00:56:19.140
But you had what I consider absolutely landmark,
link |
00:56:23.340
beautiful paper published in Nature a few years ago,
link |
00:56:26.900
showing that if you disrupt the exposure to light
link |
00:56:32.740
or the timing of the exposure to light,
link |
00:56:34.940
that there are dramatic effects on the stress system
link |
00:56:38.100
and on the learning and memory system.
link |
00:56:41.220
We could talk about each of those separately or together.
link |
00:56:44.380
What are the effects on stress and the effects on learning
link |
00:56:48.020
when light viewing behavior
link |
00:56:50.940
and sleep-wake cycles are disrupted?
link |
00:56:53.180
Yeah.
link |
00:56:54.260
So just to remind you, you know that,
link |
00:56:57.500
but to remind your listeners
link |
00:56:59.260
that I was trained as a circadian biologist.
link |
00:57:01.700
So I really was indoctrinated into thinking
link |
00:57:05.820
that light has to affect the clock,
link |
00:57:07.620
which then cause all these different effects.
link |
00:57:10.100
So that's what I believe.
link |
00:57:11.860
That's my dogma.
link |
00:57:12.700
That's what would have made me really happy.
link |
00:57:14.660
And then Tara LeGates and Cara Ultimas joined the lab
link |
00:57:18.860
and said, and we started discussing a lot of data
link |
00:57:21.580
and we said, what if there is a direct effect of light
link |
00:57:24.140
that we're missing independent of the circadian clock?
link |
00:57:27.180
So this is not an easy question to answer
link |
00:57:29.940
because as we've been talking all along,
link |
00:57:32.020
light affects the circadian clock.
link |
00:57:33.620
So how could you give light at different times of the day
link |
00:57:37.420
and not mess up the circadian clock?
link |
00:57:39.260
Luckily, we came up with such a way
link |
00:57:41.020
and that's why it was important to do this experiment
link |
00:57:44.900
the way we did them.
link |
00:57:46.420
And we proved that this light-dark cycle
link |
00:57:48.860
does not disrupt the clock.
link |
00:57:50.300
There is still a circadian rhythm
link |
00:57:52.420
and does not cause sleep deprivation.
link |
00:57:55.860
And yet, surprisingly,
link |
00:57:58.100
if you give light at the wrong time of the day,
link |
00:58:00.100
even without disrupting the circadian clock
link |
00:58:02.740
or without causing sleep deprivation,
link |
00:58:04.980
as you mentioned, you get huge mood changes
link |
00:58:08.580
in the organisms and you get learning deficit.
link |
00:58:12.700
So this really, and at the time,
link |
00:58:15.500
people have really hit us hard.
link |
00:58:17.820
I mean, it was really hard to publish this work
link |
00:58:21.100
and you could, yeah.
link |
00:58:22.700
Well, it came out in nature, so in the end you prevailed.
link |
00:58:26.820
But I want to make sure that I understand.
link |
00:58:28.300
So you're saying that, yes,
link |
00:58:30.940
there are effects of light on the circadian rhythm.
link |
00:58:33.020
Absolutely.
link |
00:58:33.860
Sleep, meaning sleep and wake fullness.
link |
00:58:35.380
Yes.
link |
00:58:36.220
And their timing.
link |
00:58:37.380
However, there are direct effects of light on mood
link |
00:58:40.820
that can be dissociated
link |
00:58:42.220
from the effects on sleep and waking.
link |
00:58:44.820
So if I interpret that correctly,
link |
00:58:47.140
that could mean that when we view light
link |
00:58:50.900
and how much light could make us feel happier
link |
00:58:54.980
or less happy or even depressed,
link |
00:58:56.780
stress, learning, et cetera.
link |
00:58:59.620
Bingo.
link |
00:59:00.460
Even if we're sleeping
link |
00:59:01.980
and waking up at the appropriate time.
link |
00:59:03.860
Bingo.
link |
00:59:04.700
I mean, eventually,
link |
00:59:06.020
because we're talking about the whole system,
link |
00:59:08.020
eventually when you start having the other problems,
link |
00:59:10.380
you also develop sleep problems.
link |
00:59:12.860
But you're absolutely right.
link |
00:59:14.140
And in fact, now research from Diego Fernandez
link |
00:59:17.660
in the lab have found that now we know
link |
00:59:20.580
that they actually require different brain regions.
link |
00:59:23.060
So we don't only have a theory,
link |
00:59:25.140
we don't only have a light environment
link |
00:59:26.900
that showed they can be dissociated.
link |
00:59:29.180
We know that they use completely different brain regions.
link |
00:59:32.260
So the SCN that I told you about earlier,
link |
00:59:34.540
the place where the central pacemaker is,
link |
00:59:36.660
the one that receives direct input from the retina
link |
00:59:39.380
through the iPRGCs to adjust your circadian clock
link |
00:59:43.060
is not the area that receives the light input
link |
00:59:45.980
for mood regulation.
link |
00:59:47.020
It's a completely different brain region.
link |
00:59:48.980
What's the brain region called?
link |
00:59:50.140
So the brain region,
link |
00:59:51.020
we called it the perihabineular nucleus.
link |
00:59:54.020
I'm not so sure how good or bad the name,
link |
00:59:55.820
but doesn't matter, it's the PHB.
link |
00:59:57.980
And what's really amazing,
link |
00:59:59.140
this region also receives direct input from the iPRGCs,
link |
01:00:02.700
but projects to areas in the brain
link |
01:00:04.500
that are known to regulate mood,
link |
01:00:06.220
including the ventral medial prefrontal cortex,
link |
01:00:10.540
which has been studied for many years
link |
01:00:13.140
to be impacted in a human depression.
link |
01:00:15.980
So just by this amazing serendipity
link |
01:00:19.820
to find that a region that is so deep in the advanced brain,
link |
01:00:25.060
like the prefrontal cortex is your executive brain,
link |
01:00:29.020
one of the most elaborated in humans,
link |
01:00:32.020
to see that they receive input
link |
01:00:34.020
from these ancient photoreceptor was stunning to us
link |
01:00:38.220
and told us how much we didn't understand
link |
01:00:40.380
the importance of light on a human behavior.
link |
01:00:43.100
So how does that finding inform daily protocols
link |
01:00:47.620
for you or for other people?
link |
01:00:48.940
I realize you can't leap to always from one paper
link |
01:00:52.460
to daily protocols,
link |
01:00:53.660
but if light indeed does control prefrontal cortex,
link |
01:00:57.100
executive function, learning, stress, and mood,
link |
01:01:02.420
and let's say I'm waking up each morning and I'm sleeping,
link |
01:01:05.180
what should I do differently?
link |
01:01:06.660
That's why we came up with the tripartite model,
link |
01:01:08.900
because yes, we could think about just adjusting the clock
link |
01:01:12.140
with lights in and being dark throughout the day,
link |
01:01:14.860
but that may not be important
link |
01:01:16.380
for your whole physiological function.
link |
01:01:17.900
So now if we include these other effects of light,
link |
01:01:21.660
that's why I prefer to still get a lot of light in the day.
link |
01:01:24.700
I don't wanna be in very dim light condition
link |
01:01:26.900
throughout the day.
link |
01:01:27.740
I see.
link |
01:01:28.580
So even though it doesn't affect your clock,
link |
01:01:30.660
as you beautifully said, Andrew,
link |
01:01:32.140
it may affect your mood and learning and memory.
link |
01:01:34.780
It may affect your alertness level,
link |
01:01:36.580
which is gonna allow you to learn better.
link |
01:01:38.540
It may affect your homeostatic drive.
link |
01:01:41.140
Maybe your homeostatic factor will go higher
link |
01:01:43.500
so you could sleep earlier.
link |
01:01:45.260
So it's important to think of light
link |
01:01:47.580
as stimulating all these brain regions,
link |
01:01:49.820
which means it's producing more activity,
link |
01:01:52.340
which in reality,
link |
01:01:53.260
this is how people think of the homeostatic drive,
link |
01:01:55.620
that the more active you are,
link |
01:01:57.180
the more the homeostatic drive is built up,
link |
01:01:59.740
the better you sleep.
link |
01:02:01.500
So that's why we came up with the tripartite model,
link |
01:02:04.580
because as a circadian biologist,
link |
01:02:06.540
I only thought of light
link |
01:02:07.700
through the circadian clock affecting behavior.
link |
01:02:10.240
As a sleep biologist,
link |
01:02:11.300
they only thought of the homeostatic drive
link |
01:02:13.460
affecting sleep, affecting behavior.
link |
01:02:15.780
And for people who study light for vision and other things,
link |
01:02:18.620
they thought only of the environmental input.
link |
01:02:21.000
But now if you put them all together,
link |
01:02:22.860
you get with this tripartite model
link |
01:02:24.700
where it's really mind-boggling,
link |
01:02:26.660
and it makes so much sense.
link |
01:02:28.320
The organism doesn't wanna depend on a single component,
link |
01:02:31.620
but if you could incorporate these three together,
link |
01:02:34.700
you could have a beautiful system that is well-adapted.
link |
01:02:38.080
So let me tell you the sleep-wake cycle, right?
link |
01:02:40.340
So we know there is a homeostatic drive to affect sleep.
link |
01:02:43.580
We've had beautiful talks about that.
link |
01:02:45.860
Which is basically the longer you're awake,
link |
01:02:47.460
the more you wanna be asleep.
link |
01:02:48.420
So that's your homeostatic drive.
link |
01:02:50.300
We've talked about the circadian influence of sleep
link |
01:02:52.900
and the fact that light-dark cycle affect
link |
01:02:54.980
the circadian system, which eventually affects sleep.
link |
01:02:58.060
So these two components are well-understood.
link |
01:03:00.260
Now the third factor is your direct light
link |
01:03:03.180
or environmental input.
link |
01:03:04.780
How much stress, how much light you get from there
link |
01:03:07.280
also can highly impact sleep.
link |
01:03:09.640
So even if you have a good circadian and homeostatic drive,
link |
01:03:13.320
if you're getting light at the wrong time of the day,
link |
01:03:15.780
or if you're being stressed and thinking,
link |
01:03:18.100
then your sleep's gonna suffer.
link |
01:03:19.820
So you have to think of the three together
link |
01:03:22.660
to have a beautiful sleep-wake cycle.
link |
01:03:25.840
And that's why we came up with the tripartite motor.
link |
01:03:28.100
The same thing happens with feeding.
link |
01:03:29.700
I could beautifully put it to people.
link |
01:03:31.740
Your hunger, your energy level is measured
link |
01:03:34.280
by the arcuate nucleus.
link |
01:03:36.140
Your daily intake of food is, again,
link |
01:03:38.300
dependent on the SCN and light-dark input.
link |
01:03:41.140
We found that if food is not available,
link |
01:03:43.960
there is yet a third input that is not dependent on the SCN,
link |
01:03:48.540
not dependent on the arcuate,
link |
01:03:49.780
depending on a completely different brain regions.
link |
01:03:52.820
So the animal can actually start looking,
link |
01:03:54.980
or the human can start looking for food when it's scarce,
link |
01:03:58.520
even at time when they are not supposed to be active.
link |
01:04:01.520
So that's how the organism think.
link |
01:04:03.180
They have to evaluate multiple inputs for them to decide
link |
01:04:07.340
what is the best physiological outcome at that moment,
link |
01:04:10.320
at that season.
link |
01:04:11.300
I see.
link |
01:04:12.940
So I wanna get into arcuate and feeding,
link |
01:04:14.680
but just to make sure we can keep our hands
link |
01:04:17.380
around this tripartite model.
link |
01:04:19.500
So if I understand correctly,
link |
01:04:20.640
we've got the circadian influence,
link |
01:04:23.000
then you've also got the drive to sleep.
link |
01:04:25.500
Actually, one of the ways that I think
link |
01:04:27.540
that can be best understood is if somebody ever pulls
link |
01:04:30.700
an all-nighter, they get tired around 11 or 12 or so,
link |
01:04:35.340
and then very tired around three, four a.m.,
link |
01:04:38.500
but then even if you stay up,
link |
01:04:40.340
sometime right around seven or eight a.m.,
link |
01:04:41.980
your normal wake-up time, you start to feel alert again.
link |
01:04:44.140
And that's because the sleep drive is extremely strong,
link |
01:04:47.960
but there's a circadian rhythm that drives wakefulness
link |
01:04:50.380
in the morning.
link |
01:04:51.220
Okay, so that's two of the components.
link |
01:04:53.720
Before we get into the feeding component,
link |
01:04:55.300
I wanna talk about these direct effects of light on mood.
link |
01:04:58.020
Okay, Diego Fernandez's data.
link |
01:05:01.100
And this perihabenular thing.
link |
01:05:03.560
So let's just, for the moment,
link |
01:05:06.240
set aside the tri part of the tripartite model
link |
01:05:08.740
and just focus on what are the direct effects
link |
01:05:10.860
of light on mood?
link |
01:05:12.180
And the way that I interpret what you've said so far
link |
01:05:14.340
is that the protocol that emerges from this,
link |
01:05:16.580
if one is trying to optimize their mood,
link |
01:05:19.120
is yes, see light, view light, I should say,
link |
01:05:21.980
early in the day in order to set your circadian clock,
link |
01:05:24.560
maybe also in the evening as well.
link |
01:05:26.540
And of course, avoid light at night,
link |
01:05:28.660
get it as dim as possible.
link |
01:05:30.460
However, you said it's also a good idea
link |
01:05:35.380
to get as much bright light during the day
link |
01:05:37.260
as you safely can in order to improve your mood
link |
01:05:40.560
independently of regulating your sleep-wake cycle.
link |
01:05:43.140
And that's a hypothesis.
link |
01:05:44.340
Here's the problem where it's not gonna be
link |
01:05:46.140
as satisfying as the circadian,
link |
01:05:48.280
is that, as you know, this brain region
link |
01:05:49.980
has been discovered very recently.
link |
01:05:52.060
Habenula.
link |
01:05:52.900
The perihabenular region.
link |
01:05:54.020
We've known about it a long time,
link |
01:05:55.260
but nobody knew what it did.
link |
01:05:56.260
So we knew about the habenula,
link |
01:05:57.780
but that's why the name is confusing.
link |
01:05:59.740
It's actually not the habenula itself.
link |
01:06:01.680
It's the perihabenula.
link |
01:06:02.660
No, near the habenula.
link |
01:06:03.500
It's near the habenula.
link |
01:06:04.340
Why don't you just call it the Samaratatar nucleus?
link |
01:06:06.180
I should have, I don't know why I've done that.
link |
01:06:08.500
Maybe because if you do that, it's not okay.
link |
01:06:10.480
Okay, so for herever after, the perihabenular nucleus,
link |
01:06:14.460
we should probably call it the hotar-
link |
01:06:16.220
The hotar fernandas.
link |
01:06:17.340
How about hotar fernandas bursa nucleus?
link |
01:06:19.500
Okay, this is like nerdy science attribution stuff,
link |
01:06:22.100
but I'm just gonna call it the hotar nucleus.
link |
01:06:24.700
Wikipedia, line it up.
link |
01:06:27.060
Okay, so this structure is taking light
link |
01:06:29.340
and independent of sleep rhythms and circadian rhythms,
link |
01:06:32.320
it's driving changes in mood.
link |
01:06:34.140
How does it do that?
link |
01:06:35.020
Is this through the dopamine system,
link |
01:06:36.460
the serotonin system?
link |
01:06:37.620
We still recently,
link |
01:06:38.940
we haven't identified this region very well.
link |
01:06:41.100
We don't know what light does to it.
link |
01:06:43.180
We don't know how it interacts.
link |
01:06:44.700
So this is an area that is ripe for discoveries
link |
01:06:47.620
and we're working on this right now.
link |
01:06:49.620
But that's why I said it's not satisfying.
link |
01:06:51.780
This is like the function of sleep.
link |
01:06:54.020
Why do we sleep?
link |
01:06:55.200
We know sleep is very important to us,
link |
01:06:57.040
but we still don't have a satisfying function
link |
01:06:59.160
of why do we sleep, right?
link |
01:07:00.860
I see, but the why questions,
link |
01:07:03.460
I think it's our good friend and colleague
link |
01:07:05.640
at University of Washington, Russ Van Gelder,
link |
01:07:07.320
who always says, when somebody asks why,
link |
01:07:09.380
the best answer is just to say,
link |
01:07:11.120
I wasn't consulted at the design phase.
link |
01:07:13.060
Exactly.
link |
01:07:13.900
Right, none of us really know why.
link |
01:07:15.060
No, but the point is, maybe I shouldn't have said why.
link |
01:07:17.700
What is the function of sleep?
link |
01:07:19.220
It's still very hard to know.
link |
01:07:21.340
Why would, what is the reason organisms
link |
01:07:24.700
have to go offline for so long?
link |
01:07:28.140
You know, people assume it's for repair,
link |
01:07:29.900
assume it's for learning and memory,
link |
01:07:31.420
assume all kinds of stuff,
link |
01:07:32.740
but there is really no clear function for sleeping.
link |
01:07:37.240
There is no clear function for sleeping.
link |
01:07:39.860
I mean, if you talk to people, there are hypotheses.
link |
01:07:42.380
I mean, all we know is that if you don't sleep,
link |
01:07:44.340
or your sleep is very fractured, you get messed up.
link |
01:07:46.820
And you could die even, right?
link |
01:07:48.440
I mean, it's really bad if you don't sleep,
link |
01:07:51.700
but we don't know what is the function,
link |
01:07:54.800
what is that sleep have gone to organisms
link |
01:07:58.260
that couldn't have done with rest?
link |
01:08:00.740
What if you just could rest without sleeping,
link |
01:08:03.000
just sit down and rest?
link |
01:08:04.140
Well, my lab's trying to figure out
link |
01:08:05.780
whether or not these non-sleep deep rest protocols
link |
01:08:08.020
can compensate for sleep.
link |
01:08:09.700
And I mean, obviously sleep is better,
link |
01:08:12.100
but many people are not getting the sleep that they need.
link |
01:08:14.580
But okay, so, and if people are sensing
link |
01:08:18.320
that Samir and I are about to start talking
link |
01:08:19.980
over each other and arguing,
link |
01:08:21.020
that's always the goal when we talk, right?
link |
01:08:23.500
Unlike other scientists I interact with,
link |
01:08:25.500
when Samir and I get together,
link |
01:08:26.680
it's considered a successful conversation
link |
01:08:28.900
if we get into a big fight and then go for a big meal
link |
01:08:31.700
where I pick the restaurant.
link |
01:08:33.240
Okay, so let's talk about food and eating and appetite.
link |
01:08:38.100
You had yet another, yes,
link |
01:08:42.560
I greatly admire your success in this way.
link |
01:08:45.820
Yet another incredible discovery showing
link |
01:08:48.740
that there are direct, excuse me, effects of light
link |
01:08:52.860
on appetite and feeding behavior.
link |
01:08:55.220
Maybe you could just summarize those results for people.
link |
01:08:58.460
Honestly, that paper is the one that allowed us
link |
01:09:00.600
to come with the tripartite model
link |
01:09:02.140
because we were thinking completely wrong about it.
link |
01:09:04.860
We wanted, this experiment, it'd be fun for your audience
link |
01:09:08.660
to hear why we started this experiment.
link |
01:09:10.880
Remember that when we discovered the IPRGCs,
link |
01:09:14.020
we figured if they are the only relay
link |
01:09:17.200
to entrain the circadian clock,
link |
01:09:19.260
then you could kill them and have an animal opposite
link |
01:09:22.740
to the one that we spoke, or a human opposite
link |
01:09:24.900
to the one that we spoke about earlier,
link |
01:09:26.380
where instead of having no pattern vision
link |
01:09:29.380
and have circadian photo entrainment,
link |
01:09:31.540
we could produce an animal that have pattern vision
link |
01:09:33.960
but no circadian photo entrainment.
link |
01:09:36.080
So circadian blind.
link |
01:09:37.560
Circadian blind, but pattern sighted.
link |
01:09:40.740
And we succeeded in that.
link |
01:09:42.820
The problem when you have these animals,
link |
01:09:44.500
which I've told you many times already,
link |
01:09:46.820
is that they don't adjust to the day-night cycle.
link |
01:09:49.660
So doing experiments on them become very complicated.
link |
01:09:53.420
What is their behavior like if you don't have these cells?
link |
01:09:55.780
Are they awake and then asleep, awake and then asleep?
link |
01:09:57.180
They just drift like the humans we've talked about.
link |
01:09:59.780
They think they're in Las Vegas.
link |
01:10:01.220
They drift, exactly.
link |
01:10:02.940
They stay up later every night.
link |
01:10:04.420
They come either, depends on their clock.
link |
01:10:06.380
If their clock is shorter, they come in earlier.
link |
01:10:08.620
If their clock is longer, they come in.
link |
01:10:10.140
So they're really messed up.
link |
01:10:11.160
They really don't adjust to the,
link |
01:10:12.960
if they were in the wild,
link |
01:10:14.140
they'll be eliminated in a second, right?
link |
01:10:16.000
There is no way they'll survive.
link |
01:10:18.000
So me and Diego started talking and we're like,
link |
01:10:20.900
what if we use non-light entraining agent?
link |
01:10:23.640
And what is the strong non-light entraining agent?
link |
01:10:26.860
Food.
link |
01:10:28.020
So we thought that the light-defective animals
link |
01:10:32.660
will have more sensitivity to food entrainment
link |
01:10:34.860
because as you know more than me,
link |
01:10:36.440
this is an area that you've worked really well on.
link |
01:10:38.860
For vision, if you're image-blind,
link |
01:10:41.020
your hearing and somatosensory get improved, right?
link |
01:10:44.860
The lack of vision improves your hearing and sensation.
link |
01:10:49.660
But we found actually that
link |
01:10:51.340
if you don't have the light system,
link |
01:10:54.540
actually you're feeding,
link |
01:10:56.140
the food ability to entrain the animal
link |
01:10:57.900
goes completely to the ground,
link |
01:10:59.820
completely opposite to what we predicted.
link |
01:11:02.740
So light viewing and feeding behavior
link |
01:11:06.400
are interacting in ways that support one another.
link |
01:11:08.860
And that's why we came with the tripartite model.
link |
01:11:10.980
We figured it's different
link |
01:11:12.260
than sensation of the environment.
link |
01:11:14.280
When you sense with vision,
link |
01:11:15.740
vision and hearing interact,
link |
01:11:17.660
but your vision is a real full modality.
link |
01:11:20.180
You want to see, that's what vision want to do.
link |
01:11:23.180
You want to hear, that's what hearing want to do.
link |
01:11:25.620
You want to sense, that's what sensing want to do.
link |
01:11:28.260
But for the circadian system, light, food,
link |
01:11:32.340
all these entraining agent,
link |
01:11:33.820
they somehow have to interact to keep a coherent system.
link |
01:11:38.280
You don't just assume if you remove light,
link |
01:11:40.180
this one is going to be stronger.
link |
01:11:41.420
No, they need to know each other's.
link |
01:11:43.700
The light informs when the animal's going to eat.
link |
01:11:46.380
Well, what I like about this so much is that,
link |
01:11:49.200
you know, in the other, in the world outside of science,
link |
01:11:52.580
in which I don't really exist in,
link |
01:11:55.220
but that I see a lot of this kind of wellness,
link |
01:11:57.740
you know, stuff with this,
link |
01:11:58.620
all this mind-body integration stuff.
link |
01:12:01.940
It's interesting because people view the body
link |
01:12:05.060
more as a system, right?
link |
01:12:06.580
A system of organs that interact,
link |
01:12:08.400
as opposed to the way that standard science
link |
01:12:11.540
and medical profession is like,
link |
01:12:13.140
you work on the liver or your ear, nose and throat,
link |
01:12:15.740
or heart and lung, or brain, or.
link |
01:12:18.340
That's a great way of thinking.
link |
01:12:20.060
But the biology is integrated.
link |
01:12:22.060
Yeah.
link |
01:12:22.900
I mean, and so for somebody who's interested
link |
01:12:26.700
in affecting their eating behavior,
link |
01:12:29.340
something that you are familiar with
link |
01:12:31.620
and that we will talk more about your experiences of
link |
01:12:33.940
in a moment,
link |
01:12:36.300
how should they use light
link |
01:12:37.940
in order to adjust their eating behavior?
link |
01:12:40.660
Right.
link |
01:12:41.500
So now that I've told you about all these interactions
link |
01:12:44.180
between the different inputs to the circadian clock,
link |
01:12:47.780
just you think about it as an engineer,
link |
01:12:49.740
what would be the best thing?
link |
01:12:51.300
The best thing is to know
link |
01:12:53.260
when your food times happen in the day,
link |
01:12:56.100
when should you get light,
link |
01:12:57.380
and when is your circadian clock in your system, right?
link |
01:13:02.060
So if you eat at very specific times of the day,
link |
01:13:05.500
that's another signal that is telling your body,
link |
01:13:08.140
your clock, you're in a certain time of the day.
link |
01:13:10.620
So if you're having lunch at the correct time every day,
link |
01:13:13.320
and you're getting bright light,
link |
01:13:14.620
now you have two systems that are informing your clock,
link |
01:13:18.060
your clock is gonna be better.
link |
01:13:19.540
So regular meal times.
link |
01:13:21.020
Regular meal times that fit your circadian clock.
link |
01:13:24.180
So, and in fact, if you do that,
link |
01:13:26.380
when I started doing this,
link |
01:13:28.380
and it helped me lose weight,
link |
01:13:30.100
is that I'm exposing myself
link |
01:13:31.700
to the right amount of light, dark cycle.
link |
01:13:34.020
I'm eating at regular time.
link |
01:13:35.940
It is amazing.
link |
01:13:37.020
You will be not hungry,
link |
01:13:38.140
let's say you eat at noon.
link |
01:13:39.620
You will not feel any hunger at 11.45,
link |
01:13:42.620
and then all of a sudden the hunger jumps.
link |
01:13:45.220
This is clearly not an energy issue
link |
01:13:47.100
because it could not be that drastic.
link |
01:13:49.380
Right, no, the desire to eat is mainly driven
link |
01:13:51.540
by these cues, these hormone cues,
link |
01:13:55.940
that are very exquisitely timed to sleep-wake cycle,
link |
01:14:00.860
but also to light.
link |
01:14:02.300
Exactly.
link |
01:14:03.140
And you know, in the wild,
link |
01:14:04.540
you could imagine why energy level
link |
01:14:06.420
through the arcuate nucleus-
link |
01:14:08.420
You should explain to people what the arcuate is,
link |
01:14:10.120
because I don't think we've done that adequately.
link |
01:14:11.940
The arcuate nucleus is an area of the hypothalamus
link |
01:14:14.300
that drives hunger and feeding behavior.
link |
01:14:16.720
And what we're talking about is the fact
link |
01:14:18.300
that it's taking cues from your viewing of light,
link |
01:14:23.140
believe it or not, is impacting your level of hunger.
link |
01:14:26.260
And this is a non-trivial way
link |
01:14:29.900
in which your timing of hunger and amount of hunger
link |
01:14:32.860
is regulated by when and how much light you view.
link |
01:14:36.780
So let me ask you a couple of practical-
link |
01:14:38.780
Can I just, this is really, before you ask me,
link |
01:14:41.260
sorry, Andrew, we said we're going to fight,
link |
01:14:43.500
but to me, it's the interesting thing to think about it.
link |
01:14:46.980
In the wild, when you didn't have the availability
link |
01:14:48.980
of food that we have,
link |
01:14:50.660
the arcuate plays a huge, important role,
link |
01:14:53.220
because if you weren't successful in getting food,
link |
01:14:57.380
then the arc is going to tell you,
link |
01:14:58.620
look, you have to take risk and go get food
link |
01:15:01.160
because your energy level is very low.
link |
01:15:03.220
And that's great.
link |
01:15:04.100
That's tons of great research about that.
link |
01:15:06.420
But I think what's missing is the fact in humans,
link |
01:15:09.660
we're not getting to a situation, most of us,
link |
01:15:12.800
we're not getting to a situation
link |
01:15:14.060
where we have low energy levels.
link |
01:15:16.400
Most of the time, actually, we eat not because we want to,
link |
01:15:19.340
because we really have low energy,
link |
01:15:21.420
but because we want to eat.
link |
01:15:23.020
So I think that's why I feel that the timing
link |
01:15:26.360
is very important for us
link |
01:15:28.020
because we always have enough energy level for us to eat.
link |
01:15:31.540
Well, I mean, I enjoy eating so much that I'll eat
link |
01:15:33.860
just for the sensation of chewing.
link |
01:15:35.860
I mean, I enjoy the taste too,
link |
01:15:38.260
and I enjoy the social aspects when those are a part of it,
link |
01:15:40.960
but I literally enjoy the physical act of chewing,
link |
01:15:44.800
absolutely.
link |
01:15:46.160
Which explains a lot.
link |
01:15:49.260
Okay, so how regular are you,
link |
01:15:53.700
or do you recommend people be about meal times?
link |
01:15:56.240
Because what I'm hearing is that light viewing behavior
link |
01:16:01.020
is pretty straightforward.
link |
01:16:01.940
Get a lot of light in the morning and throughout the day,
link |
01:16:03.880
minimize it in the evening and at night, generally speaking,
link |
01:16:07.380
for sake of mood and circadian rhythm,
link |
01:16:09.120
but for sake of regulating timing and quality,
link |
01:16:14.120
I should also say a food intake,
link |
01:16:15.760
because people clearly make better choices
link |
01:16:17.520
about food intake when they are anticipating a meal
link |
01:16:20.700
and they aren't constantly hungry.
link |
01:16:22.680
And so the ability to regulate hunger
link |
01:16:24.760
for particular phases of the circadian cycle
link |
01:16:27.080
is quite valuable for all people,
link |
01:16:29.120
not just people trying to lose weight, but all people.
link |
01:16:32.300
Are we talking about down to the minute?
link |
01:16:33.980
Like if I-
link |
01:16:34.820
Absolutely not.
link |
01:16:35.640
All right, so 12 noon is my normal lunch, let's say,
link |
01:16:40.000
plus or minus?
link |
01:16:41.400
Half an hour.
link |
01:16:42.240
Okay.
link |
01:16:43.080
So eat around between 11.30 and 12.30.
link |
01:16:45.720
If that's the time, and it depends,
link |
01:16:47.960
if you also do multiple meals.
link |
01:16:49.600
Remember, three meals, that's a decision
link |
01:16:52.000
that somebody came up with.
link |
01:16:53.440
I don't know why.
link |
01:16:54.280
Nowadays, fewer people are doing that, I think.
link |
01:16:56.400
Yeah.
link |
01:16:57.240
Given our friend Sachin Panda's work.
link |
01:16:59.000
Right, I mean, so you could have two meals.
link |
01:17:01.220
You could have very multiple meals
link |
01:17:04.760
that are distributed across your active time.
link |
01:17:07.920
I agree with Sachin Panda's work
link |
01:17:10.720
that try to avoid eating when your system
link |
01:17:13.260
is supposed to be relaxing,
link |
01:17:14.840
when you're supposed to be at non-active time.
link |
01:17:18.560
So, you know, limit your eating
link |
01:17:21.000
to the active time of your cycle.
link |
01:17:23.600
And that seemed to be,
link |
01:17:24.960
and Joe Takahashi is doing some beautiful stuff on this.
link |
01:17:28.160
That seems to be incredibly important
link |
01:17:30.100
for aspect of the circadian-
link |
01:17:33.300
And for health.
link |
01:17:34.140
And for health.
link |
01:17:34.960
Yeah, I mean, Sachin,
link |
01:17:35.800
we're referring to Sachin Panda's work.
link |
01:17:37.520
He wrote a beautiful book called The Circadian Code.
link |
01:17:39.840
Maybe, Samer, with some luck,
link |
01:17:41.480
you'll write a book as well,
link |
01:17:43.440
meaning the world would be lucky to have that book.
link |
01:17:46.080
But Sachin's data really strongly points to the fact
link |
01:17:49.580
that liver health, brain health,
link |
01:17:54.180
metabolic factors and endocrine factors
link |
01:17:56.180
of various systems and organs
link |
01:17:58.580
all seem to benefit from having a period
link |
01:18:00.720
of each 24-hour day in which we are not eating anything
link |
01:18:03.620
and then eating at very regular times.
link |
01:18:06.800
Let's talk about eating in meal times
link |
01:18:08.560
and let's move a little bit away
link |
01:18:10.280
from the science for the moment,
link |
01:18:12.120
although we will return to it,
link |
01:18:13.440
and talk a little bit more about your experience
link |
01:18:16.660
with eating in meal times.
link |
01:18:18.480
So you're looking in good shape lately.
link |
01:18:21.440
Thank you.
link |
01:18:22.280
I know you've been putting work into it.
link |
01:18:23.520
Yeah.
link |
01:18:24.360
We talk a lot and you've been exercising
link |
01:18:25.920
and you've been eating well, meaning quality food.
link |
01:18:30.480
You just came back from Jordan
link |
01:18:31.540
where I'm assuming the food is amazing.
link |
01:18:33.480
It's the food is amazing.
link |
01:18:34.440
And honestly, usually I gain a lot of weight in Jordan,
link |
01:18:37.760
but this time I didn't gain any weight,
link |
01:18:40.000
which was really nice, so.
link |
01:18:41.840
Yeah, when I met you,
link |
01:18:45.120
you were probably about 100 pounds heavier than you are now.
link |
01:18:49.800
Yeah, 275 pounds, I'm 219 now, it's crazy.
link |
01:18:53.800
You had a lot of vigor then
link |
01:18:54.920
and you have a lot of vigor now,
link |
01:18:56.680
but I know that you undertook a very specific protocol
link |
01:19:01.520
in order to lose the weight.
link |
01:19:03.720
Based on your understanding of the circadian system
link |
01:19:06.280
and of light and appetite and mood,
link |
01:19:09.160
maybe you could just tell us a little bit
link |
01:19:10.520
about what that schedule looks like.
link |
01:19:12.280
And we realize that this is not a prescriptive for everybody,
link |
01:19:14.960
but you found what worked for you.
link |
01:19:17.000
Yeah.
link |
01:19:17.840
Maybe just describe those changes.
link |
01:19:18.760
I mean, honestly, I followed my circadian cycle, right,
link |
01:19:21.560
of what we've talked about, right?
link |
01:19:23.960
So I dimmed the light at night.
link |
01:19:25.800
I slept at regular hours.
link |
01:19:27.920
I ate my major food in breakfast and lunch
link |
01:19:31.020
when I'm really active and I'm really hungry.
link |
01:19:33.640
And at night, when I avoid dinner
link |
01:19:35.720
because my circadian system really shuts off at three,
link |
01:19:38.320
I'm an early person,
link |
01:19:39.860
like you could give me anything I would eat before three.
link |
01:19:42.360
After three, nothing appeals to me anymore.
link |
01:19:44.760
My system is shut off.
link |
01:19:46.080
What time are you going to sleep
link |
01:19:47.240
and what time are you waking up?
link |
01:19:48.080
Oh, so in my case, I should have put this up.
link |
01:19:50.440
I mean, I go to sleep literally at 9 p.m.
link |
01:19:53.360
I mean, I literally, five minutes after 9 p.m.,
link |
01:19:56.560
I'm completely out.
link |
01:19:58.380
And I wake up between 4.30 and 5.00 a.m.
link |
01:20:01.000
So if I extend it, I go to 6.00 a.m.
link |
01:20:03.560
But very rarely, depends on how tired I was.
link |
01:20:06.600
And that, as I recall, was an important set of changes
link |
01:20:10.600
for you to be able to regulate your food intake.
link |
01:20:12.800
Absolutely, because then I'm having very big breakfast
link |
01:20:16.760
and again, for different people, it's different.
link |
01:20:19.440
I have a big breakfast at 7 a.m. maximum.
link |
01:20:22.840
So I have a big breakfast, coffee and all this stuff.
link |
01:20:25.840
Then I have some simple snack around 10.
link |
01:20:29.020
Then I have regularly lunch at noon or between noon to one.
link |
01:20:32.800
Then I have another snack at three.
link |
01:20:34.360
And the hardest time to regulate the food
link |
01:20:36.200
is between 12 and three.
link |
01:20:37.400
This is when I really feel hungry.
link |
01:20:39.520
This is your equivalent of kind of late evening
link |
01:20:41.500
for most people.
link |
01:20:42.340
So for me, it would probably be between seven and 10 p.m.
link |
01:20:44.560
Exactly, exactly.
link |
01:20:46.360
And then at night, I'm completely not hungry.
link |
01:20:48.980
But usually, as you said, the enjoyment of food.
link |
01:20:52.620
Like when my wife cooks some really beautiful Indian food,
link |
01:20:56.080
I eat, but I'm not hungry.
link |
01:20:58.160
And I notice if I eat with that, I usually gain weight.
link |
01:21:01.120
But if I regulate that at night, I also lose weight.
link |
01:21:04.400
So there is a combination of all these things
link |
01:21:07.000
that help you adjust the input of food,
link |
01:21:11.240
the input of light, the input of the clock
link |
01:21:13.640
and the drive to hunger.
link |
01:21:15.880
Yeah, I appreciate you sharing that.
link |
01:21:17.440
And I want to emphasize that some people
link |
01:21:19.440
are not hungry early in the day.
link |
01:21:21.160
They might be late shifted people.
link |
01:21:22.640
In which case, eating later in the day
link |
01:21:24.100
will work well for them.
link |
01:21:24.940
It will work as long as they don't eat early in the morning.
link |
01:21:27.440
That's just, you have to work with your schedule,
link |
01:21:29.840
with your active schedule.
link |
01:21:31.400
Yeah, you and I have been talking about this
link |
01:21:32.800
offline for years.
link |
01:21:33.720
I'm glad we're finally having this discussion publicly now.
link |
01:21:36.680
What we're talking about really
link |
01:21:37.680
is finding your ideal sleep schedule.
link |
01:21:39.800
Exactly.
link |
01:21:40.680
And finding your ideal eating schedule.
link |
01:21:43.120
Exactly.
link |
01:21:43.960
And understanding how those two things interact.
link |
01:21:46.400
And you know, the nice thing, as you said,
link |
01:21:48.040
finding them out is going to help you
link |
01:21:49.680
to understand how they interact.
link |
01:21:51.360
Because we know from the Tripartite model
link |
01:21:53.480
that they are all interconnected.
link |
01:21:55.840
And for each person,
link |
01:21:57.040
they're going to be interconnected differently.
link |
01:21:59.600
So for each person, you would, you know, for me,
link |
01:22:03.680
if I exercise at night,
link |
01:22:05.340
I'm going to mess up my whole system.
link |
01:22:07.000
Believe it.
link |
01:22:07.840
So when do you exercise?
link |
01:22:08.660
Morning.
link |
01:22:09.500
Morning works great for me.
link |
01:22:10.440
I mean, it's amazing.
link |
01:22:11.800
Morning exercise for me works great.
link |
01:22:14.800
I tried one time because it was easier for me
link |
01:22:17.240
to exercise at night before I leave
link |
01:22:19.240
when the traffic is there from the night.
link |
01:22:21.360
And I think that messed me up
link |
01:22:22.740
because I couldn't sleep well,
link |
01:22:24.640
and I couldn't wake up well,
link |
01:22:26.040
and that led to more changes in my food.
link |
01:22:27.840
I gained weight again, actually, believe it or not,
link |
01:22:30.840
even though I was exercising.
link |
01:22:32.600
So I think this really makes me think
link |
01:22:35.360
that you have to think of the Tripartite model
link |
01:22:38.160
to see where is the best times
link |
01:22:41.320
and what is the best interrelation
link |
01:22:43.200
between the different component, as you beautifully said,
link |
01:22:45.880
between your meal times, your light exposure,
link |
01:22:48.320
and your sleep that works for you.
link |
01:22:50.800
Well, thank you for that.
link |
01:22:51.620
Usually Samir's insulting me today.
link |
01:22:53.360
He's complimenting me.
link |
01:22:54.560
I'm going to compliment him right back by saying,
link |
01:22:57.120
this is the first time that I've ever really understood
link |
01:23:01.480
how, yes, light can control sleep.
link |
01:23:04.460
Yes, it can control mood.
link |
01:23:07.080
Yes, it can impact feeding,
link |
01:23:09.040
but that it's really about doing the self-exploration
link |
01:23:11.700
to align those in the way that works best.
link |
01:23:14.560
And what I'm hearing, tell me if I'm wrong,
link |
01:23:16.520
but what I'm hearing is that once you understand
link |
01:23:19.320
what gives you the best sleep-wake cycle,
link |
01:23:21.960
then you should exercise during the period of time
link |
01:23:25.500
in which you feel most alert.
link |
01:23:27.640
And if it works for your schedule,
link |
01:23:30.680
ideally you would also eat during the time
link |
01:23:32.900
in which you feel most alert and then stop eating
link |
01:23:35.800
and stop light viewing behavior as you head towards sleep.
link |
01:23:38.280
Right.
link |
01:23:39.120
So the only thing I would say that complicates all of this,
link |
01:23:42.240
and that's what makes me sad, is your light exposure.
link |
01:23:45.100
Mine personally?
link |
01:23:45.940
No, I'm just kidding.
link |
01:23:47.640
The people's light exposure, right?
link |
01:23:49.860
This is what complicates it
link |
01:23:51.400
because you're not going to be able to figure all this out
link |
01:23:55.000
if you're shifting yourself out of your comfort zone
link |
01:23:57.740
by viewing light at the wrong time of the day.
link |
01:24:01.240
So let's say if you were under an idle natural conditions,
link |
01:24:07.000
you're a person who would sleep later than me,
link |
01:24:09.240
let's say we'll sleep at midnight and wake up at 8 a.m.
link |
01:24:12.960
Let's say you don't eat anything till noon,
link |
01:24:15.000
and as you said, you eat late in the evening,
link |
01:24:17.860
then this would be perfect for you.
link |
01:24:19.600
But now see what happens
link |
01:24:21.440
if now you include the light component.
link |
01:24:23.320
Now if you push your sleep from midnight to 4 a.m.,
link |
01:24:26.820
now you're waking up in the morning
link |
01:24:29.280
and you're actually really not the morning,
link |
01:24:31.880
you're working up, sorry, at noon instead of eight o'clock,
link |
01:24:35.040
and the time where you're not supposed to be hungry,
link |
01:24:37.480
now you're gonna start eating directly at noon
link |
01:24:39.740
or something like that, or even delay it.
link |
01:24:42.260
And now you're shifting your whole cycle
link |
01:24:43.960
and you don't know if this interaction
link |
01:24:45.680
between your sleep feeding and the light dark environment
link |
01:24:48.440
are still gonna be maintained or not.
link |
01:24:50.600
And that's the problem that people have.
link |
01:24:52.520
So as I'm hearing this, what I'm realizing is most of us,
link |
01:24:56.680
probably me included, are messing up at least one,
link |
01:25:00.400
two, or three of these components.
link |
01:25:02.440
But that the probe, the way to figure out
link |
01:25:06.480
what's right for oneself
link |
01:25:08.000
is to start manipulating light exposure.
link |
01:25:10.640
And I'm gonna be honest, I'm biased,
link |
01:25:13.880
because I believe that light is the strongest time giver.
link |
01:25:18.000
And a lot of people disagree.
link |
01:25:19.600
Some people think feeding is.
link |
01:25:21.080
I always thought that light was the primary zeitgeber,
link |
01:25:23.360
the primary light.
link |
01:25:24.200
Yeah, but a lot of people think it's food.
link |
01:25:25.800
A lot of people even sometimes mention social interactions.
link |
01:25:28.600
And they read the literature?
link |
01:25:29.960
I agree with you.
link |
01:25:31.040
I totally agree with you.
link |
01:25:32.440
I mean, my understanding is that light
link |
01:25:33.940
is the most powerful driver of the things we're talking about.
link |
01:25:36.040
That's why I think we need to regulate this first
link |
01:25:38.680
and everything else fits.
link |
01:25:40.420
And you know, the nice thing is that
link |
01:25:42.200
your sleep-wake cycle and exercise tell you really bluntly
link |
01:25:45.820
if you're doing it right or not.
link |
01:25:47.200
Tell me more about that.
link |
01:25:48.120
I'll tell you more.
link |
01:25:48.960
When I shifted my exercise,
link |
01:25:51.440
honestly, things fell apart like never before.
link |
01:25:54.280
When you moved from exercising early in the day
link |
01:25:56.600
to late in the day.
link |
01:25:57.520
It completely fell apart for me.
link |
01:25:59.480
I didn't enjoy exercise at night.
link |
01:26:01.480
My pain tolerance for exercise wasn't as good.
link |
01:26:04.280
I'm talking with N equals one, and I'm aware of this.
link |
01:26:06.480
I've never tested this empirically.
link |
01:26:08.680
But at least to me, it really messed up everything.
link |
01:26:12.360
I started having problems,
link |
01:26:13.480
because my body temperature will go up,
link |
01:26:15.560
and that will affect my sleep.
link |
01:26:17.000
I possibly was running in the gym with a lot of lights,
link |
01:26:19.440
so maybe the light was a component.
link |
01:26:22.240
But for me, exercising in the morning,
link |
01:26:24.680
it's so much better for me.
link |
01:26:26.520
But a lot of people can't even think
link |
01:26:28.220
of exercising in the morning.
link |
01:26:29.760
So it depends on when you feel comfortable
link |
01:26:31.960
in your sleep-wake cycle and your exercise.
link |
01:26:34.160
I think that tells you if your system
link |
01:26:35.880
is in synchrony with one another.
link |
01:26:38.480
That's really interesting.
link |
01:26:39.480
You know, we're good friends.
link |
01:26:41.120
Our friend Pat Dossett, right, that we both know,
link |
01:26:43.660
you know, did nine years in the SEAL teams,
link |
01:26:45.720
and he's one of these people.
link |
01:26:47.120
He says, you know, he's happy to go for a run or swim
link |
01:26:49.380
any time between 4.30 a.m. and 6 a.m.
link |
01:26:52.560
And he'll train in the afternoon, too,
link |
01:26:54.160
because, you know, he's a SEAL team guy,
link |
01:26:55.800
and they'll do whatever any time.
link |
01:26:57.380
That's part of the phenotype.
link |
01:26:58.820
But he feels best doing that, right?
link |
01:27:01.480
I'm a mid, I like to exercise mid-morning,
link |
01:27:04.360
and I'm happy to skip eating until 12 or one.
link |
01:27:08.160
And I like to go to sleep around 11, 30, 12,
link |
01:27:10.160
because I'm a normal human being rather than you
link |
01:27:12.020
who goes to bed at 9 p.m.
link |
01:27:12.860
What about Pat, actually, I've never asked him what time.
link |
01:27:15.960
So, Pat's ideal to sleep time.
link |
01:27:18.080
I've asked him, this would be around 8.30 or 9.
link |
01:27:20.800
Oh, I sound like Pat.
link |
01:27:21.800
No, but he has, yes, but he has two young children,
link |
01:27:25.880
two years old and a newborn,
link |
01:27:27.600
and so the cycle is disrupted, right?
link |
01:27:29.680
Yeah, but that's known, right?
link |
01:27:31.320
I mean, the effect of childbearing,
link |
01:27:33.480
and I think we could talk about this,
link |
01:27:35.600
that's more complicated, but that's pretty much, yeah.
link |
01:27:39.080
Yeah, I mean, I think we need to come up with a new name
link |
01:27:41.520
for a chronotype, because chronotype implies
link |
01:27:44.840
that it's just about sleep and wake,
link |
01:27:47.000
being an early bird or a night owl,
link |
01:27:48.800
and what we're also talking about is how exercise
link |
01:27:51.200
and eating match onto those.
link |
01:27:53.000
And the phase relation between them.
link |
01:27:56.000
Right.
link |
01:27:56.840
And the phases between different components, as you said.
link |
01:27:59.400
Because they interact.
link |
01:28:00.400
Because they interact.
link |
01:28:01.240
Right.
link |
01:28:02.060
And they don't have to be in the same phase.
link |
01:28:03.480
Like, let's say my light and food
link |
01:28:05.520
could be very close to each other's,
link |
01:28:06.960
your light and food could be different, right?
link |
01:28:09.320
The phases don't have to be, they can't be plastic.
link |
01:28:11.840
So you have to find this for yourself.
link |
01:28:14.120
You may be a person who eats late at night,
link |
01:28:17.000
exercises late at night,
link |
01:28:18.920
or you may be a person who exercises early, eat later.
link |
01:28:21.480
So it doesn't, as long as the phase is good,
link |
01:28:25.200
that's what you have to find out.
link |
01:28:27.320
Okay, and if I understand correctly,
link |
01:28:28.880
when you're talking about phase relationship,
link |
01:28:30.320
it means you want to lump exercise, feeding, and light for-
link |
01:28:34.080
And sleep.
link |
01:28:34.920
And sleep, in a way that,
link |
01:28:37.360
as a coherent and total system,
link |
01:28:39.600
makes you feel really good.
link |
01:28:41.160
Temporally, in a great order.
link |
01:28:43.260
Uh-huh.
link |
01:28:44.100
Absolutely.
link |
01:28:44.920
Yeah, that's, and I think that-
link |
01:28:45.760
And I could tell you, to me,
link |
01:28:47.520
is literally getting exposed to sun,
link |
01:28:50.880
you know, clearly in the morning,
link |
01:28:52.480
clearly at noon I go out,
link |
01:28:53.960
I keep my windows in the office completely open,
link |
01:28:57.400
eating mostly in the early time of the day,
link |
01:28:59.760
and exercising, and literally at the end part of the day,
link |
01:29:03.400
I'm literally in a more thoughtful, vegetative state.
link |
01:29:07.640
Like, I really can't, like after five,
link |
01:29:10.360
I tell my students,
link |
01:29:11.200
if you want to tell me anything complicated,
link |
01:29:13.120
you're wasting your time.
link |
01:29:14.360
My brain just doesn't function.
link |
01:29:16.360
So even though I only sleep at night,
link |
01:29:17.900
but I'm really starting to shut off, ramp down,
link |
01:29:21.160
really, I mean, it's, you know,
link |
01:29:23.120
I could send the email, talk about brainless stuff,
link |
01:29:26.160
but my power, my energy to do powerful stuff
link |
01:29:30.560
really dropped tremendously.
link |
01:29:32.280
So all my students who know me very well,
link |
01:29:34.320
they put the meetings with me early in the morning,
link |
01:29:36.960
because they know this is when I'm,
link |
01:29:38.600
so everything for me, and for me, it's very tight.
link |
01:29:41.600
So it could be different for,
link |
01:29:43.040
it's very clustered in the morning, it's all tied together,
link |
01:29:45.960
and literally the remaining part seems to be just a,
link |
01:29:48.880
you know, vegetative state.
link |
01:29:51.400
Yeah, you and my bulldog Costello,
link |
01:29:54.640
who unfortunately passed away recently,
link |
01:29:56.400
had that in, yeah.
link |
01:29:57.240
Oh no, I did not, that's so sad.
link |
01:29:58.120
Sam and Costello were good friends.
link |
01:29:59.540
Yeah, sorry to break it to you here.
link |
01:30:01.540
Yeah, he had a good long life and he went easy,
link |
01:30:04.420
but he had a circadian clock
link |
01:30:06.220
that basically would just sleep around 24 hours a day.
link |
01:30:09.720
Minimal activity interspersed every third day or so.
link |
01:30:13.800
You do have this morning vigor,
link |
01:30:16.160
and that's, I think other people are going to have
link |
01:30:18.800
more of an afternoon vigor.
link |
01:30:19.860
Do you think that this can change across the lifespan?
link |
01:30:23.020
It's, the rumor is that teenagers naturally want
link |
01:30:27.220
to sleep in later and stay up later.
link |
01:30:29.400
Do you think that social rhythm,
link |
01:30:30.800
or do you think that that's actually biological?
link |
01:30:32.480
Yeah, that's a tough question.
link |
01:30:33.840
I mean, it could be both.
link |
01:30:37.400
One thing that worries me is that it seems that
link |
01:30:40.640
if anything with age, this morning rigor gets stronger.
link |
01:30:44.760
You mean you want people to become more of morning?
link |
01:30:46.600
More of morning.
link |
01:30:47.440
But why is that worry you?
link |
01:30:48.260
I think that's good.
link |
01:30:49.100
Because for me, I'm already a very shifted morning.
link |
01:30:51.720
I don't want to be one of these 7 p.m.
link |
01:30:53.720
to 1 a.m. sleepers at some point.
link |
01:30:55.800
Yeah, on the other hand, it's also kind of nice
link |
01:30:57.600
because it's quiet and you can get work done.
link |
01:30:59.440
But honestly, from 4.30 to 7.30, when my wife wake up,
link |
01:31:03.660
it can be very lonely.
link |
01:31:05.800
Yes, you achieve a lot, but it's quiet outside.
link |
01:31:08.920
It's, you know, so I don't want to be at 1 a.m.
link |
01:31:12.120
Let's put it this way.
link |
01:31:12.960
I don't want to.
link |
01:31:13.800
You can tell Samra is more social than I am.
link |
01:31:15.560
That's right.
link |
01:31:16.380
That is true.
link |
01:31:17.220
But we should touch on that actually.
link |
01:31:18.580
So your wife is, she follows a different schedule.
link |
01:31:22.080
Yeah.
link |
01:31:22.920
And so the social rhythm is important.
link |
01:31:26.320
I think, what should we do?
link |
01:31:27.840
How should we conceptualize
link |
01:31:29.740
and how should we adjust ourselves
link |
01:31:31.680
according to the social rhythm?
link |
01:31:32.520
And I honestly love this hypothesis
link |
01:31:35.360
that people came up with and Pat's kids reminded me of.
link |
01:31:39.320
Because kids are really gonna disrupt your sleep-wake cycle,
link |
01:31:42.880
it seems like there is a chrono attraction
link |
01:31:46.640
that usually people who attract each others
link |
01:31:48.980
have actually different sleep-wake schedule.
link |
01:31:51.840
And the idea being is that this allows them
link |
01:31:54.200
to take care of their kids throughout the day-night cycle.
link |
01:31:57.520
And have a peaceful marriage.
link |
01:31:58.720
And have a peaceful marriage in a way, right?
link |
01:32:01.200
So, I mean, we didn't have kids me and Rachel,
link |
01:32:03.440
so maybe this is, but it seems like evolutionary,
link |
01:32:06.520
it makes sense that if you want to protect your kids,
link |
01:32:09.920
you don't want everybody to be mourning rigor
link |
01:32:12.040
and then the kids don't have,
link |
01:32:13.640
so you want the distributed across.
link |
01:32:15.880
It makes sense.
link |
01:32:16.700
It's a reasonable argument.
link |
01:32:17.840
I've heard that one of the reasons
link |
01:32:20.160
that people think that the clock is not exactly 24 hours,
link |
01:32:24.640
but is 24 hours plus or minus 20 minutes or so
link |
01:32:28.400
is because we believe that we evolved in clans or groups,
link |
01:32:33.760
villages, whatever, that we're about 100 to 200 people.
link |
01:32:37.040
And in order to have protection around
link |
01:32:40.240
the early morning hours when we're vulnerable to predation,
link |
01:32:43.900
and in the late night hours that you would want
link |
01:32:46.160
some individuals of our species to be naturally
link |
01:32:49.080
more like night owls and some more like early people.
link |
01:32:51.260
So your theory of parenting is similar in that way.
link |
01:32:55.920
Right.
link |
01:32:56.760
The social rhythm is a powerful rhythm though.
link |
01:32:59.160
Meaning if I go out and I'm tired,
link |
01:33:02.600
let's say I'm tired at like 9.30, I don't want to go out,
link |
01:33:04.880
like I'm gonna need it.
link |
01:33:05.720
So can I just say something about that?
link |
01:33:06.840
I think the social rhythm is powerful at the obvious levels,
link |
01:33:11.380
like it affects your sleep,
link |
01:33:13.240
it affects how much you wake up or eat,
link |
01:33:15.860
but I'm not so sure it's as powerful
link |
01:33:17.720
as people think on the clock.
link |
01:33:19.760
Now, eventually it will mess up the clock
link |
01:33:21.760
because now if you're doing a lot of social at night,
link |
01:33:24.720
getting enough light, eating at the wrong time of the day,
link |
01:33:27.000
eventually you're gonna have an effect.
link |
01:33:29.760
But I don't think that's the social interactions themselves
link |
01:33:33.840
have been shown to affect your clock very strongly
link |
01:33:36.280
for some reason.
link |
01:33:37.400
That's good to know.
link |
01:33:38.580
Well, for people hearing this,
link |
01:33:40.560
they're probably getting the impression,
link |
01:33:42.220
like I'm the night owl and then Samir is the one
link |
01:33:45.340
that's in bed at nine and then, you know, wakes up at four,
link |
01:33:48.860
but having attended many meetings with Samir,
link |
01:33:51.300
I can tell you that he's the party animal.
link |
01:33:53.480
So let's talk about that.
link |
01:33:55.960
I mean, let's talk about the fact that you're the partier
link |
01:33:58.640
who's up until two dancing at these various meetings,
link |
01:34:01.800
which I've seen, actually a good dancer I'm told,
link |
01:34:05.620
but what should we do when we do stay up very late
link |
01:34:10.880
for whatever reason?
link |
01:34:11.880
Could be because we had to take a midnight trip
link |
01:34:13.740
to the hospital, unfortunate reason,
link |
01:34:15.640
or it could be because you're in the presence of people
link |
01:34:18.360
that you don't see very often,
link |
01:34:19.640
and you go out for a really nice night out on the town
link |
01:34:22.940
and you get to sleep around 2.30 or three in the morning.
link |
01:34:27.180
How should one get back on schedule?
link |
01:34:29.120
Do you force yourself to then get up and view light
link |
01:34:31.320
at the normal time that you would get up and view light,
link |
01:34:33.440
or do you allow yourself to sleep in?
link |
01:34:35.000
What's the optimal protocol?
link |
01:34:36.280
I would allow myself to sleep in,
link |
01:34:37.800
and remember, this is a long-term effect.
link |
01:34:39.980
This is something that you live with for a long period.
link |
01:34:42.600
And remember, I told you about the experiments
link |
01:34:45.200
we did with the mood.
link |
01:34:46.240
These require two weeks of that light schedule
link |
01:34:48.920
to cause mood disturbances.
link |
01:34:50.520
So these don't happen just in a single day.
link |
01:34:52.740
So this is the way you justify staying out late
link |
01:34:55.080
every once in a while?
link |
01:34:55.900
Well, in the meetings you've seen me,
link |
01:34:58.040
and I've done this for five or six days continuously,
link |
01:35:00.600
but what you didn't see that when I came back to my home,
link |
01:35:03.400
it took me two weeks, as if I did a jet lag.
link |
01:35:05.920
So I really do suffer for two weeks
link |
01:35:08.240
after doing a six crazy night of staying up at night,
link |
01:35:12.120
drinking at the wrong time of the day.
link |
01:35:14.000
So it's not that I'm completely okay with it.
link |
01:35:16.880
When I go back, everything goes back.
link |
01:35:18.520
It takes me actually literally two weeks to recover
link |
01:35:21.340
from the circadian rhythm meeting
link |
01:35:23.200
that you've seen me partying at at some point.
link |
01:35:25.840
Which is kind of ironic, the circadian rhythm meeting.
link |
01:35:28.400
People are totally disrupting the circadian cycle,
link |
01:35:30.560
but scientists are human beings too.
link |
01:35:32.640
Right, so I think if you do it at very little occasions,
link |
01:35:38.360
I think you should not worry too much
link |
01:35:40.960
that this will have a lasting impact.
link |
01:35:42.800
And the good news is that if you readjust your schedule,
link |
01:35:45.940
you could come back to it.
link |
01:35:47.160
The problem is when you maintain these wrong schedule
link |
01:35:50.280
for a prolonged team, it becomes chronic,
link |
01:35:53.120
prolonged periods of time.
link |
01:35:54.240
That's when you have the problems
link |
01:35:55.960
and the accumulation of the problems.
link |
01:35:58.120
So when you have sleeping problem,
link |
01:36:00.320
you produce metabolic problem.
link |
01:36:01.720
When you have metabolic problems,
link |
01:36:02.980
you produce lack of exercise,
link |
01:36:04.820
and you could see how things can spiral out very quickly,
link |
01:36:08.340
and then it would be hard to come back to it.
link |
01:36:11.040
Well, certainly sleep disruption is both a symptom of
link |
01:36:13.960
and a cause of almost all mental health disorders, right?
link |
01:36:19.680
And certainly the metabolic syndromes
link |
01:36:22.040
that people are talking about nowadays and all of this,
link |
01:36:25.080
it all funnels back to light.
link |
01:36:28.040
This is what's so remarkable.
link |
01:36:30.040
And so we have these devices,
link |
01:36:31.720
and I use my phone and I use my computer,
link |
01:36:35.160
but do you think that the mere dimming of the screen
link |
01:36:38.480
or not interacting with screens after,
link |
01:36:42.080
with say 90 minutes or two hours before bedtime,
link |
01:36:45.760
according to what we're saying today,
link |
01:36:48.920
this should have a profound effect on all these factors.
link |
01:36:52.120
And I really believe it does.
link |
01:36:53.520
And I, again, I think as Pat has did these inventions
link |
01:36:59.440
where you get a pouch where you put your phone in a pouch.
link |
01:37:02.880
So what Samra's referring to is our friend, Pat,
link |
01:37:06.120
this former SEAL team member that we,
link |
01:37:08.840
who's also a very impressive person
link |
01:37:10.620
in the landscape of business and family, et cetera,
link |
01:37:12.760
a real superhuman from, by any regard,
link |
01:37:17.220
has this habit of taking his phone
link |
01:37:19.000
and putting it into a sealed pouch in the evening.
link |
01:37:21.600
So it's basically-
link |
01:37:22.560
And in his program, he sends you actually these seal,
link |
01:37:26.200
you know, patches.
link |
01:37:27.040
And so that I think is a great idea
link |
01:37:30.280
because not only it will take away the light from you,
link |
01:37:33.400
but it also take away the distraction
link |
01:37:35.200
because you wanna repair and recover and sleep does that.
link |
01:37:39.860
And if you have your phone dinging all the time
link |
01:37:42.280
or the light flashing from it,
link |
01:37:45.000
you're just not getting enough sleep
link |
01:37:46.640
and you're causing yourself major problems.
link |
01:37:50.840
I never asked you this,
link |
01:37:51.960
but I realize now that I should have long ago,
link |
01:37:57.080
but I'll ask you now,
link |
01:37:59.100
why and how did you get into all this stuff?
link |
01:38:02.360
Yeah, I mean, honestly, I, first of all,
link |
01:38:05.100
I wanted to become a, you know,
link |
01:38:07.160
I wanted to study genetics
link |
01:38:08.660
and I knew I wanted to do PhD in genetics,
link |
01:38:11.860
but I only got accepted in one university at the time
link |
01:38:14.520
and I joined the learning and memory lab.
link |
01:38:16.860
And I liked learning and memory.
link |
01:38:18.120
At the beginning, I worked in the snails
link |
01:38:19.840
on a plesia californica
link |
01:38:21.280
and started looking at learning and memory,
link |
01:38:23.200
but then the same lab was looking at these daily variation.
link |
01:38:26.720
I was really struck.
link |
01:38:28.440
Like you never think about it outside of science.
link |
01:38:31.040
It really struck me that organisms can measure day,
link |
01:38:36.640
biologically, that was very shocking to me.
link |
01:38:39.120
And I just really got attracted
link |
01:38:41.160
and I wanted to see why does this happen?
link |
01:38:44.540
What is the effect of different times of day?
link |
01:38:46.400
And I just stuck with it.
link |
01:38:47.720
It's just, it was mind blowing for me,
link |
01:38:50.140
who was in medical school
link |
01:38:52.000
that I've never heard about it before.
link |
01:38:54.380
You know, it's really amazing medicine.
link |
01:38:56.200
I think still now we are very good
link |
01:38:58.960
at looking at stuff spatially,
link |
01:39:01.160
but we're very bad at looking at temporal aspects.
link |
01:39:04.640
So we always, you know, like to see images,
link |
01:39:06.920
static images, spatial information.
link |
01:39:09.520
Take an X-ray, measure a temperature,
link |
01:39:11.280
measure a blood pressure.
link |
01:39:12.120
Exactly, but we don't think of temporal.
link |
01:39:14.880
And you know, you talk to John Huganash right now
link |
01:39:17.480
and he's telling you the importance of chronomedicine
link |
01:39:20.480
or chrono pharma, pharma two, whatever the word is.
link |
01:39:24.040
And it just, it really just getting the drugs
link |
01:39:27.680
at the right time of the day
link |
01:39:29.000
is gonna be essential for our health.
link |
01:39:31.480
Do you think that's gonna come from using better trackers
link |
01:39:33.960
like aura rings, whoop straps, these kinds of things?
link |
01:39:37.320
I love the trackers,
link |
01:39:38.400
but I think there's even more exciting discoveries.
link |
01:39:40.840
Now you could take a single blood sample
link |
01:39:42.920
and measure many biological components
link |
01:39:45.600
and figure where you are in the circadian clock,
link |
01:39:48.160
something that was very hard to do before.
link |
01:39:50.640
So if you have a marker to know where you are in the clock,
link |
01:39:53.480
you could actually understand more the effect
link |
01:39:56.080
of everything, exercise, feeding, light input.
link |
01:39:58.760
What is the marker?
link |
01:39:59.960
So there are some papers from, what's her name,
link |
01:40:03.440
Phyllis Zee and from Haim Kramer,
link |
01:40:06.960
where they measure multiple RNAs
link |
01:40:08.840
that are known to tell you what phase of the clock is
link |
01:40:11.840
or multiple proteins or biological reactions.
link |
01:40:16.640
And depending on a combination of factor,
link |
01:40:19.160
not a single factor,
link |
01:40:20.120
you could tell where you are in the circadian clock.
link |
01:40:23.360
So they could, instead of just measuring temperature
link |
01:40:25.880
or melatonin, just one measurement.
link |
01:40:27.840
And melatonin specifically is also complicated
link |
01:40:29.880
by the fact that melatonin is affected by light.
link |
01:40:32.760
And temperature, your temperature and sleep
link |
01:40:36.120
can be easily dissociatable, right?
link |
01:40:38.280
When you travel across different times on your sleep
link |
01:40:40.320
at different times in the temperature cycle.
link |
01:40:43.280
So having multiple components measured
link |
01:40:46.000
will give you a better determination of your circadian phase
link |
01:40:49.760
and understanding your circadian phase in humans
link |
01:40:53.200
will tell you what is the effect
link |
01:40:54.680
of giving certain drugs
link |
01:40:56.000
at certain times of the circadian phase.
link |
01:40:57.680
So in the future, this is gonna be studied
link |
01:41:00.280
at a much higher level when you can determine the phase
link |
01:41:03.600
in relation to all the other stuff.
link |
01:41:07.000
It's striking to me that in all animals, besides humans,
link |
01:41:12.040
if they deviate too much from the appropriate exposure
link |
01:41:15.280
to light and light-dark cycle,
link |
01:41:16.840
they essentially don't mate and or die
link |
01:41:20.480
and or get killed off.
link |
01:41:22.320
But in humans, we are able to override that
link |
01:41:25.080
at least to some extent.
link |
01:41:26.600
But the ways in which we suffer appear to be things like
link |
01:41:31.360
obesity, metabolic syndromes, reproductive syndromes
link |
01:41:35.240
that accompany the other syndromes, endocrine syndromes
link |
01:41:38.360
and mood and depressive disorders.
link |
01:41:41.240
Is there any effort at the level of the nationally
link |
01:41:45.600
or laboratories that you're aware of
link |
01:41:47.600
to try and use light in order to improve mood
link |
01:41:51.360
and mental health?
link |
01:41:52.400
I mean, honestly, this is my mantra.
link |
01:41:54.520
This is the thing that I think people,
link |
01:41:57.200
because I say, don't take a pill, take a photon.
link |
01:42:01.360
I mean, you take pills, it's important.
link |
01:42:03.000
I'm just making it that really,
link |
01:42:05.240
we have an opportunity right now
link |
01:42:07.440
with the incredible advances of LED lights,
link |
01:42:10.440
of changing spectrum of light, of regulating intensities.
link |
01:42:15.920
And just for simple changes,
link |
01:42:19.000
you could really improve sleep-wake cycle, productivity,
link |
01:42:22.880
and still you could actually get more done
link |
01:42:25.520
because as we've talked about,
link |
01:42:27.480
when you have all these messed up,
link |
01:42:29.520
now you have to sleep more, but your sleep is fragmented.
link |
01:42:32.880
It's not very good.
link |
01:42:34.040
And you can't focus when you use it.
link |
01:42:34.880
And you can't focus when you don't have alertness
link |
01:42:37.440
when you need the alertness.
link |
01:42:39.280
So having all these could allow you to do even more
link |
01:42:43.160
actually at the end than less.
link |
01:42:45.200
And that's the exciting part of it.
link |
01:42:47.920
One of the questions I get asked most often about
link |
01:42:50.400
is about ADHD.
link |
01:42:52.200
I think there's a lot of self-prescribed
link |
01:42:54.120
as well as clinically prescribed ADHD.
link |
01:42:56.200
People are having a tremendously difficult time focusing
link |
01:42:58.880
and not just because they're sleepy,
link |
01:43:00.560
they just can't seem to anchor their attention.
link |
01:43:02.240
And there could be multiple reasons for this,
link |
01:43:04.160
but there are now several clinical trials ongoing
link |
01:43:06.800
using light to try and anchor people's attention
link |
01:43:09.880
and mood and wellbeing for sake of focus.
link |
01:43:12.000
And I think that while I love this saying
link |
01:43:14.480
that you mentioned, take a photon, not a pill,
link |
01:43:17.640
and with due respect to the need for pharmacology
link |
01:43:21.480
for certain people, I think most people
link |
01:43:24.600
just haven't really dialed in their relationship to light
link |
01:43:27.160
in a way that allows them to rule out
link |
01:43:28.680
whether or not they need medication.
link |
01:43:30.560
Absolutely.
link |
01:43:31.400
That's the best way to put it.
link |
01:43:32.640
I can't add to that.
link |
01:43:34.760
Let's talk about jet lag, but not in the context of,
link |
01:43:39.480
okay, if somebody's traveling from Europe to Japan
link |
01:43:42.640
or from the East Coast, because that varies tremendously,
link |
01:43:44.840
right?
link |
01:43:45.680
I mean, there's as many different variations
link |
01:43:47.000
on travel as there are individuals out there
link |
01:43:49.640
and with goals and jobs, et cetera,
link |
01:43:52.440
but rather let's talk about what are the two or three things
link |
01:43:55.840
that people can do to adjust their schedule quickly.
link |
01:43:59.400
Yesterday, I called you and said, look,
link |
01:44:01.720
I know somebody who's traveling six hours.
link |
01:44:04.040
I won't even mention in which direction
link |
01:44:05.440
because I don't want people to anchor to that example.
link |
01:44:08.120
And you described some very simple tools of viewing light
link |
01:44:13.760
a little bit earlier than normal
link |
01:44:15.760
and getting on the local food schedule, et cetera,
link |
01:44:18.560
that would allow them to shift more quickly.
link |
01:44:20.720
And the reason I want to have this conversation is yes,
link |
01:44:22.920
for the travelers and for the shift workers,
link |
01:44:25.800
but mostly because of the fact that you've proven
link |
01:44:30.160
again and again that people are disrupted
link |
01:44:33.600
in their circadian behavior at home.
link |
01:44:36.280
So what are the, aside from what we've already talked about,
link |
01:44:39.000
how can one adjust quickly to a new schedule?
link |
01:44:42.320
Like let's say fall classes are starting,
link |
01:44:44.080
you start a new job or you have a baby or a puppy
link |
01:44:46.320
or whatever, what is the best way
link |
01:44:48.480
to shift the clock quickly?
link |
01:44:50.200
So it's very simple as we've talked yesterday.
link |
01:44:52.600
So imagine you're in the outside with no industrial light.
link |
01:44:59.000
If your body thinks you're in early evening
link |
01:45:02.080
and you see a bright light, what does this tell you?
link |
01:45:04.960
Oh, wait, this is not early evening yet.
link |
01:45:07.600
It's still early afternoon or late afternoon.
link |
01:45:11.160
So I have to delay my clock to go back to late afternoon.
link |
01:45:14.880
So if you get light early in the evening,
link |
01:45:18.120
it delays your clock.
link |
01:45:20.040
So what does-
link |
01:45:20.880
Meaning that makes you want to go to sleep later.
link |
01:45:22.840
Yes, it delays your clock.
link |
01:45:24.000
So you're in New York, right?
link |
01:45:27.760
People in Italy have an advanced clock
link |
01:45:29.760
because they are six hours ahead of us.
link |
01:45:33.000
So if you're in New York and you get light early
link |
01:45:36.800
in the evening, you delay even further from Italy.
link |
01:45:39.440
So now you're delaying away from Italy.
link |
01:45:42.080
Now, the same thing happens.
link |
01:45:43.600
Let's say you thought dawn came up
link |
01:45:45.720
and you thought it's already dawn,
link |
01:45:47.720
but it was, let's say, three o'clock in the morning
link |
01:45:49.800
or four o'clock in the morning.
link |
01:45:50.840
And then you get a bright light and you say,
link |
01:45:52.720
oh, wait a minute, dawn is not up yet.
link |
01:45:55.800
So I should advance my clock.
link |
01:45:57.400
Or I'm at night, but I'm getting bright light
link |
01:46:01.400
so I should run because dawn is already up.
link |
01:46:04.640
So then later in the night, later in your night,
link |
01:46:09.240
and actually it just happens that the humans,
link |
01:46:11.920
you get a temperature in the day or later in the night,
link |
01:46:14.800
low temperature in your body.
link |
01:46:16.520
After that, light start advancing your clock.
link |
01:46:20.040
So if you want to go to Italy,
link |
01:46:21.560
instead of getting light early in the evening,
link |
01:46:23.440
you want to get light after the temperature low.
link |
01:46:26.680
So you could advance your clock even before you go to Italy
link |
01:46:30.040
and you're catching up to the Italians just by using light.
link |
01:46:32.920
It's as simple as that.
link |
01:46:34.360
So you could do it for every region.
link |
01:46:36.680
You could calculate how much they are advanced of you.
link |
01:46:39.960
You could know how much these light shifts happen per day,
link |
01:46:43.000
and you can calculate what you need to do,
link |
01:46:45.920
very simple math, to adjust either in direction of delaying,
link |
01:46:49.880
if you're going from New York to California,
link |
01:46:51.720
you want to delay your clock,
link |
01:46:53.360
or advancing if you're going from New York to Italy.
link |
01:46:56.280
So in order to make that a visual,
link |
01:46:58.560
and because a lot of people are listening to this,
link |
01:47:00.200
not looking at it on video,
link |
01:47:01.800
we will put a zero-cost downloadable figure of this
link |
01:47:07.000
on the Hubermanlab.com website related to this episode.
link |
01:47:10.280
But I think I can summarize it in language as well.
link |
01:47:14.440
If I understand correctly, what you're saying is,
link |
01:47:17.520
if your typical wake-up time is, say, 7 a.m.,
link |
01:47:21.160
then your low point in temperature
link |
01:47:23.000
probably occurs somewhere around 5 a.m.
link |
01:47:26.280
And if you view light right around then,
link |
01:47:29.360
it's going to essentially advance your clock.
link |
01:47:31.720
Because then your body thinks,
link |
01:47:33.720
oh, it's 7 o'clock, so it'll advance your clock
link |
01:47:35.640
by one to two hours.
link |
01:47:37.000
But if I were to view light, say, at 3 a.m.,
link |
01:47:40.760
then it would probably delay my clock.
link |
01:47:42.680
Yeah. Okay.
link |
01:47:43.880
Yeah, so, and then let's say I land in a new schedule.
link |
01:47:47.160
I want to adjust to a new schedule.
link |
01:47:48.320
Let's say I didn't manage to do anything
link |
01:47:50.000
with my light viewing before I went,
link |
01:47:51.440
and I didn't anticipate the trip.
link |
01:47:53.480
Suddenly, I'm on a new schedule, okay?
link |
01:47:56.200
I was told that one of the ways to help shift the clock
link |
01:47:59.760
and to avoid gastrointestinal issues
link |
01:48:02.080
is to eat on the local schedule,
link |
01:48:05.240
to start basically behaving like a local,
link |
01:48:08.240
even though your circadian clock
link |
01:48:10.400
will take a little bit of time to catch up.
link |
01:48:11.960
Absolutely.
link |
01:48:12.800
But you have to remember the light, right?
link |
01:48:15.360
So let's, now that we explained it very simply,
link |
01:48:17.960
let's take a very simple example, right?
link |
01:48:20.800
New York to Italy.
link |
01:48:22.160
That's a simple example.
link |
01:48:23.840
New York time, Italy time, six-hour difference, right?
link |
01:48:26.800
So let's say you fly from New York at night.
link |
01:48:29.640
You reach Italy at eight o'clock in the morning.
link |
01:48:31.840
What is the time in your New York time?
link |
01:48:34.800
Although you reach-
link |
01:48:35.640
Six hours back.
link |
01:48:36.480
Six hours back.
link |
01:48:37.320
It's two a.m.
link |
01:48:38.480
So when you land Italy,
link |
01:48:39.800
you want to avoid light like the plague.
link |
01:48:42.160
Yeah, you could eat,
link |
01:48:43.200
but you really don't want to get a light.
link |
01:48:44.960
Right, because otherwise it's going to delay you.
link |
01:48:45.800
It's going to delay you.
link |
01:48:46.840
It's going to send you to California
link |
01:48:48.320
instead of sending you to Italy.
link |
01:48:49.640
Right, and so this is such a key point.
link |
01:48:51.560
If anyone's confused about this,
link |
01:48:52.920
we will put some diagrams up,
link |
01:48:54.240
but what Samir's saying is so crucial.
link |
01:48:57.720
Just because getting bright light in your eyes
link |
01:49:00.120
early in the day is really beneficial when you're at home.
link |
01:49:02.440
When you travel to a new time zone,
link |
01:49:04.920
you have to take into account what your body thinks,
link |
01:49:09.480
what, excuse me,
link |
01:49:10.520
you have to take into account
link |
01:49:11.960
where your body thinks you are.
link |
01:49:13.480
And so if you're looking at the Italian sunrise,
link |
01:49:15.520
having just flown from New York to Italy,
link |
01:49:17.880
and you didn't prepare for that trip
link |
01:49:19.400
by waking up a little bit earlier in anticipation.
link |
01:49:21.600
Multiple days, yeah.
link |
01:49:22.440
And you view light at two a, excuse me,
link |
01:49:24.640
at six or seven a.m. Italian time.
link |
01:49:27.560
Beautiful Italian sunrise.
link |
01:49:29.360
You are going to delay your clock.
link |
01:49:31.040
You're going to basically throw yourself back to California,
link |
01:49:33.920
but you are in Italy.
link |
01:49:35.200
You're going to throw your biology back to California
link |
01:49:37.240
and you are going to be up
link |
01:49:38.320
in the middle of the Italian night
link |
01:49:40.000
and you're going to be miserable.
link |
01:49:42.400
I'll tell a brief anecdote
link |
01:49:44.120
because I called Samir in desperation a few years ago.
link |
01:49:47.560
I traveled to Abu Dhabi, NYU Abu Dhabi to give a seminar.
link |
01:49:50.760
12 hours out of phase, it's a 12 hour flip.
link |
01:49:53.040
And I thought I could just muscle it.
link |
01:49:55.160
I thought I'll get up,
link |
01:49:56.000
I'll just view sunlight when the sun comes up.
link |
01:49:58.320
And I fell apart mentally and physically.
link |
01:50:02.040
And Samir came to my rescue.
link |
01:50:04.280
I called him.
link |
01:50:05.120
I said, I don't know what to do.
link |
01:50:06.040
And he said, go to the gym,
link |
01:50:08.720
went at the local dawn,
link |
01:50:12.560
work out, eat,
link |
01:50:14.920
and then view sunlight starting the next day.
link |
01:50:18.320
And that basically got me onto schedule.
link |
01:50:19.880
So I used food and exercise to adjust myself
link |
01:50:22.160
because my light viewing activity
link |
01:50:24.040
was just completely out of whack.
link |
01:50:25.520
Yeah, I mean, and we talked about other details.
link |
01:50:28.080
So you have to calculate it,
link |
01:50:29.640
but you're absolutely right.
link |
01:50:31.040
I mean, it's very important
link |
01:50:34.120
to avoid getting the wrong light information
link |
01:50:36.760
when you're trying to adjust your body
link |
01:50:38.360
because otherwise it shifts you to the other side.
link |
01:50:41.800
Absolutely right.
link |
01:50:43.200
Well, you are one of these people that has such vigor.
link |
01:50:47.400
It's one of these things
link |
01:50:48.280
where having known you all these years,
link |
01:50:50.200
you have a tremendous capacity for work
link |
01:50:52.720
and for soccer and for arguing, respectful arguing.
link |
01:50:57.000
And, you know, sometimes, you know-
link |
01:50:58.520
It's getting worse with age.
link |
01:50:59.880
Yeah, well, we could talk about that offline,
link |
01:51:01.800
but I think a lot of your vigor
link |
01:51:04.400
and a lot of your ability to work hard and focus
link |
01:51:06.840
and really do so many things at an impressive level
link |
01:51:10.160
is because you think about these issues
link |
01:51:11.800
and you think about when you're going
link |
01:51:13.840
to be optimal for focus,
link |
01:51:15.560
when you're going to be optimal for exercise,
link |
01:51:17.440
when, and the when is the key.
link |
01:51:20.440
And I think a lot of people live in the landscape
link |
01:51:22.440
of feeling like there's something broken inside them
link |
01:51:25.120
because they can't focus.
link |
01:51:26.520
It's subconscious, right?
link |
01:51:27.880
Remember, it's all subconscious, these effects.
link |
01:51:30.840
And you're absolutely right.
link |
01:51:32.120
Now, honestly, joking aside about age,
link |
01:51:35.200
I really agree with you that I think part of the reason
link |
01:51:37.960
I'm continuing to be able to do this,
link |
01:51:40.000
that I really think about it
link |
01:51:42.120
and I make sure that I keep everything aligned.
link |
01:51:45.360
And that actually helps me a lot.
link |
01:51:47.600
Like I don't suffer in sleep.
link |
01:51:49.920
I don't suffer in waking up.
link |
01:51:51.120
I never use a timer to wake up.
link |
01:51:53.560
I mean, people say, aren't you scared?
link |
01:51:55.160
Like you have to give a lecture at eight or 7.30.
link |
01:51:57.920
Honestly, I was like,
link |
01:51:58.760
there is no way I'm going to go beyond that.
link |
01:52:01.080
It just, even if I try,
link |
01:52:02.480
I can't sleep beyond 6 a.m. in my regular times.
link |
01:52:05.680
It's just, it's not going to happen.
link |
01:52:07.400
By 4.30, my eyes are wide awake and I'm in bed.
link |
01:52:10.720
It's just, system is so aligned, it works.
link |
01:52:15.760
A lot of times people will say,
link |
01:52:17.160
how come I go to sleep?
link |
01:52:18.320
I fall asleep fine,
link |
01:52:19.400
but then I wake up at three or four in the morning
link |
01:52:21.160
and can't fall back asleep.
link |
01:52:22.720
Is it possible that those people
link |
01:52:24.200
were supposed to go to bed at 8 p.m.?
link |
01:52:26.320
It's possible.
link |
01:52:27.200
I mean, it is possible.
link |
01:52:28.760
It is also possible that sometimes people will wake up
link |
01:52:31.560
and go back to sleep.
link |
01:52:32.720
But yeah, I mean, it is possible,
link |
01:52:35.480
or it's possible that their clock is completely misaligned,
link |
01:52:38.560
that they are getting maybe a nap time at night
link |
01:52:41.520
when they are supposed,
link |
01:52:42.360
and then they possibly feel so sleepy in the day.
link |
01:52:44.400
So all these are possible combinations.
link |
01:52:46.880
Well, that's an interesting idea and considered.
link |
01:52:48.600
So what they think is their sleep,
link |
01:52:50.680
their body is so out of whack with the light dark cycle
link |
01:52:53.520
that it's actually a nap.
link |
01:52:55.160
Or the weaker part of the sleep.
link |
01:52:57.080
I mean, you see this when you travel
link |
01:52:59.760
to different time zones before you adjust.
link |
01:53:02.240
You go to sleep really well,
link |
01:53:03.920
but two hours later you're fully up.
link |
01:53:06.360
Two hours.
link |
01:53:07.320
If you were so tired and this is your regular sleep,
link |
01:53:09.840
there's no way you're gonna wake up in two hours.
link |
01:53:13.280
So then you feel very sleepy later in the day
link |
01:53:16.360
or something like that.
link |
01:53:17.280
So it depends on how your whole system
link |
01:53:20.120
is aligned to the environment.
link |
01:53:21.560
That's a very interesting idea.
link |
01:53:23.080
I think that's gonna resonate with a lot of people.
link |
01:53:26.880
I wake up every morning around three or four.
link |
01:53:30.560
I generally use the bathroom
link |
01:53:32.440
and then I fall back asleep very deeply.
link |
01:53:34.720
Doesn't seem to disrupt my daytime wakefulness.
link |
01:53:37.360
And I think a lot of people obsess over that waking up
link |
01:53:40.360
and worry there's something wrong.
link |
01:53:41.760
Provided they can go back to sleep, it's okay.
link |
01:53:43.800
If you can't go use the bathroom, go back to sleep,
link |
01:53:46.560
that should not be a problem.
link |
01:53:48.120
Maybe some people when they go to use the bathroom,
link |
01:53:50.280
they use very bright light
link |
01:53:51.560
and then they get an alerting signal.
link |
01:53:53.680
So if you, maybe that could be as simple as that,
link |
01:53:57.120
that affects you.
link |
01:53:57.960
Maybe when you wake up, you put tons of light
link |
01:54:00.400
or you start reading your iPad.
link |
01:54:02.440
So there's all these combination
link |
01:54:04.120
that we still don't know about
link |
01:54:05.680
that could be affecting their sleep wake rhythms
link |
01:54:08.040
and their sleep maintenance.
link |
01:54:10.360
Do you use melatonin or do you take melatonin?
link |
01:54:13.440
I don't need it to be honest.
link |
01:54:14.680
In my case, there is no reason to use it
link |
01:54:16.880
because I could guarantee you that by maybe eight o'clock,
link |
01:54:20.840
my melatonin has already started to go up.
link |
01:54:23.080
And by the time I sleep, my melatonin is very high
link |
01:54:25.600
because I don't use a lot of lights after sunset.
link |
01:54:29.120
And light inhibits melatonin.
link |
01:54:30.640
And life really blocks melatonin level.
link |
01:54:33.480
You hear this myth that the pineal gland
link |
01:54:36.440
calcifies as we get older.
link |
01:54:38.280
Is that, do you know anything about that?
link |
01:54:39.640
I mean, I've heard about that, but I don't know what does,
link |
01:54:42.400
I mean, there is not very clear evidence
link |
01:54:44.280
that affects the sleep.
link |
01:54:45.440
I don't know much about it, to be honest.
link |
01:54:47.480
The evidence that I've seen is that yes,
link |
01:54:49.080
there's some calcification around the pineal,
link |
01:54:51.240
just because of where it sits in the brain.
link |
01:54:54.640
It's close to some bony structures,
link |
01:54:57.720
but I don't think there's any evidence
link |
01:54:59.480
that it has negative effects.
link |
01:55:01.600
I mean, if you still have, you could measure melatonin
link |
01:55:04.560
and that should tell you if it has any,
link |
01:55:06.040
it's such an easy thing to do.
link |
01:55:08.040
I think this is more of a internet wellness thing
link |
01:55:11.080
that got outside the cage.
link |
01:55:14.360
I think you're absolutely right.
link |
01:55:15.440
Yeah, it sounds terrible calcification
link |
01:55:18.040
of the thing, right?
link |
01:55:20.120
The hard thing, right?
link |
01:55:21.240
Yeah, exactly.
link |
01:55:23.880
Let's talk about seasonality a little bit.
link |
01:55:27.720
I learned, and I don't know if this is still true,
link |
01:55:32.160
but that most suicides occur in April, in the spring.
link |
01:55:37.360
I think there's a poem that says,
link |
01:55:38.800
April is the cruelest month, I think is the poem begins.
link |
01:55:44.440
Are there data that suicides are more frequent
link |
01:55:47.160
at particular times of year?
link |
01:55:48.560
And if so, is the spring that time of year?
link |
01:55:50.760
Yeah, I mean, a lot of people talk about this.
link |
01:55:53.000
And one of the hypothesis is that the winter months
link |
01:55:56.960
that are very bad for mood
link |
01:55:59.520
make people not wanting to do anything.
link |
01:56:01.960
And they get into such deep level of depression
link |
01:56:05.480
that when the sun comes up,
link |
01:56:07.040
they get actually the energy to act on their depression,
link |
01:56:09.920
which sounds really terrible, and it is terrible.
link |
01:56:12.720
It's terrible.
link |
01:56:13.760
So that's the idea that the lack of light
link |
01:56:16.000
throughout the winter caused them to go into such depression
link |
01:56:19.040
that they don't feel like doing anything.
link |
01:56:21.640
And when the light comes in with rigor in the spring,
link |
01:56:25.000
it gives them that,
link |
01:56:26.360
after all the depression they suffered,
link |
01:56:28.160
gives them that push to take that sad final act, I guess.
link |
01:56:34.480
What other seasonal effects have been demonstrated
link |
01:56:36.920
in humans?
link |
01:56:37.760
Yeah, I mean, I think in humans,
link |
01:56:39.280
it's not very clear because we don't think about seasonality.
link |
01:56:42.440
But if you start thinking about us,
link |
01:56:45.400
I think we go through major seasonal changes.
link |
01:56:47.960
I really do.
link |
01:56:48.800
I think our eating pattern change across the year,
link |
01:56:51.680
I could tell you that me thinking about this,
link |
01:56:54.520
there's a clear changes that happens to me across the year.
link |
01:56:58.440
But for animals, this is really essential.
link |
01:57:00.800
Because for animals, they have to time their mating behavior
link |
01:57:05.280
was when they deliver their progeny
link |
01:57:07.920
in the most abundant amount of food.
link |
01:57:10.680
And artificial light is causing major disruption
link |
01:57:13.920
because if you change the way these animals
link |
01:57:16.560
are receiving the light information,
link |
01:57:18.920
they either start mating much earlier or much later,
link |
01:57:22.040
and their numbers dwindle,
link |
01:57:23.560
and they get into the dangers
link |
01:57:25.800
of really completely getting eliminated or extinct.
link |
01:57:28.960
Well, human birth rates are definitely going down.
link |
01:57:31.400
I mean, in the U.S. in particular.
link |
01:57:33.880
Some areas, not others.
link |
01:57:35.320
Not others, right.
link |
01:57:38.040
But are there other effects of seasonality on humans
link |
01:57:41.360
that we are aware of?
link |
01:57:42.840
Honestly, like you could see it,
link |
01:57:44.400
honestly, you could see it perfectly, I think,
link |
01:57:46.840
in Scandinavia.
link |
01:57:48.280
I mean, you could talk to people who live in.
link |
01:57:51.280
Sure, they get seasonal depression.
link |
01:57:53.080
Well, seasonal depression is one,
link |
01:57:54.600
but actually when you start asking them questions,
link |
01:57:57.000
they tell you like in the winter,
link |
01:57:58.600
they barely could wake up,
link |
01:58:00.600
they barely have the energy before even depression.
link |
01:58:03.520
Even people who don't get seasonal depression,
link |
01:58:05.960
they'll tell you our energy level is lower,
link |
01:58:08.080
our ability to go to work is not the same.
link |
01:58:11.280
And in the summer, most people actually sleep very little.
link |
01:58:15.000
They tell you we really can,
link |
01:58:17.560
we feel like we're manic, we have all this energy,
link |
01:58:21.280
and not in a negative way, in a funny way, right?
link |
01:58:23.720
I mean, but if you wanna sleep,
link |
01:58:25.240
we have to put this curtain.
link |
01:58:27.120
I think in these situations,
link |
01:58:29.160
you could really appreciate the seasonality of humans.
link |
01:58:32.600
I think we kind of destroyed our seasonality
link |
01:58:35.600
because we don't get exposed to that much natural light.
link |
01:58:39.760
We have all this artificial light.
link |
01:58:41.440
But I think, honestly,
link |
01:58:43.280
one of the things that is gonna happen,
link |
01:58:45.360
if they follow your recommendations
link |
01:58:47.320
about giving light at the same time,
link |
01:58:49.640
giving food, giving exercise.
link |
01:58:51.080
Wait, let's be clear, those are your recommendations.
link |
01:58:52.680
Well, I mean. No, I'm just fair attribution.
link |
01:58:56.080
What I'm saying is that this is gonna cause them
link |
01:58:58.480
to also experience some changes across the season
link |
01:59:01.680
because now, they're gonna see the sun differently.
link |
01:59:04.920
If you're gonna go out in the morning,
link |
01:59:07.400
in the summer, you're gonna get a much brighter,
link |
01:59:09.480
that's why I don't like the change in time.
link |
01:59:11.200
I know people think, oh, because you're biased,
link |
01:59:14.640
because I think.
link |
01:59:15.480
Wait, wait, wait, sorry.
link |
01:59:16.440
The change now, are you talking about daylight savings?
link |
01:59:18.160
Daylight savings, it's such a bad idea
link |
01:59:20.480
because it disrupts that rhythm that you're having.
link |
01:59:24.160
Because I think your body, if you keep that rhythm,
link |
01:59:27.040
you will see the whole seasonality.
link |
01:59:28.800
And I look at it from a different aspect than other people.
link |
01:59:32.160
It really, and people say I'm biased
link |
01:59:34.200
because I'm a morning person, and it may be true.
link |
01:59:37.120
But there's situation.
link |
01:59:38.960
Secret conspiracy about morning people.
link |
01:59:41.040
Yeah, but there is, if you think about it, Andrew,
link |
01:59:43.720
there is a situation where you're getting light
link |
01:59:46.840
perfectly well, and then all of a sudden,
link |
01:59:48.480
they delay it by one hour.
link |
01:59:50.640
And then, even though it's the summer,
link |
01:59:53.040
your body now, if you're still not adjusting,
link |
01:59:55.600
think, oh, wait, what happened?
link |
01:59:57.360
What kind of happened?
link |
01:59:58.480
Well, I'm glad you're bringing this up
link |
01:59:59.760
because I always thought, what's the big deal?
link |
02:00:03.080
One hour, right?
link |
02:00:04.200
One hour shift, spring forward, fall back.
link |
02:00:06.400
It's so hard to adjust to one hour action.
link |
02:00:08.000
But this goes back to the beginning of our discussion.
link |
02:00:11.680
It's not just one hour.
link |
02:00:13.160
Right.
link |
02:00:14.000
Because it's one hour across that one day,
link |
02:00:16.120
but there's this cumulative effect on the clock
link |
02:00:18.520
and these three elements of your tripartite model.
link |
02:00:22.920
The homeostatic sleep and the direct effects on mood.
link |
02:00:25.880
And when it's so close, it's sometimes hard to figure out
link |
02:00:29.600
how to adjust it perfectly because, you know,
link |
02:00:32.160
we're already sleep deprived in our society.
link |
02:00:34.600
And then you shift it by, you know,
link |
02:00:36.680
so it just, it all accumulates and it has no benefit.
link |
02:00:40.720
Well, you work at a major government organization,
link |
02:00:42.800
National Institute of Mental Health.
link |
02:00:44.200
Why don't we campaign for-
link |
02:00:46.040
Honestly, I have no idea.
link |
02:00:47.560
I mean, it makes no sense.
link |
02:00:48.400
No, I'm saying, why don't we go campaign?
link |
02:00:50.040
Yeah, I would love to.
link |
02:00:51.000
I mean, it makes no sense to have the summer light
link |
02:00:54.400
goes up at 9 p.m.
link |
02:00:56.360
The light goes down where I live in Baltimore at 9 p.m.
link |
02:00:59.800
And then all of a sudden, when you really want to
link |
02:01:03.240
see the light longer in the day,
link |
02:01:04.840
you now shift the other way.
link |
02:01:06.520
And now it goes all of a sudden at 6 p.m.
link |
02:01:08.360
Why do you do these drastic changes?
link |
02:01:10.040
Well, let it blend across the whole season.
link |
02:01:13.600
You know, yes, later, earlier at night,
link |
02:01:16.120
but it's at least consistent.
link |
02:01:17.960
It goes in a very consistent manner.
link |
02:01:20.120
I just don't understand why they do this.
link |
02:01:22.040
It makes no sense.
link |
02:01:23.360
Well, I think that the reason they do it
link |
02:01:25.840
is because they don't understand the biology.
link |
02:01:28.320
Because one hour seems trivial,
link |
02:01:30.280
unless you understand the repercussions
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02:01:33.040
of that one hour shift.
link |
02:01:34.480
Because what's also clear now,
link |
02:01:36.880
based on what you're saying,
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02:01:37.760
is that that one hour shift is taking you
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02:01:40.080
out of alignment with the natural light dark cycle
link |
02:01:42.680
in exactly the wrong direction.
link |
02:01:44.840
It's pushing people to get even later in the summer
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02:01:48.280
when light is going to push you later anyway.
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02:01:51.000
It doesn't make sense.
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02:01:52.160
You put it beautifully.
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02:01:53.120
I just rambled and this is new.
link |
02:01:55.320
No, no, you made it clear.
link |
02:01:56.800
I mean, it's like literally it made you,
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02:01:59.400
it made people who are having problem
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02:02:02.040
having an advanced sleep rhythm because they are delayed.
link |
02:02:05.200
Now you give them this hour to make them even more delayed.
link |
02:02:08.120
You push them even later in the day and night cycle.
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02:02:10.840
It just doesn't make sense at all.
link |
02:02:14.400
I think 2022 should be the year
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02:02:16.640
that we abolish bad daylight savings.
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02:02:18.960
That would be the day for me, honestly.
link |
02:02:20.480
Well, also if it has a positive effect on the,
link |
02:02:25.480
what is essentially an epidemic of mental health issues
link |
02:02:28.960
and other issues related to
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02:02:30.520
improper interactions with light,
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02:02:33.280
that I think is a well worthwhile cause.
link |
02:02:37.200
And we can explore.
link |
02:02:38.880
So for once we're going to fight with some,
link |
02:02:41.040
with another group, a common battle
link |
02:02:43.280
as opposed to with one another.
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02:02:44.120
I mean, the circadian people, honestly,
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02:02:46.080
to give them credit have been trying for years
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02:02:48.320
to abolish daylight saving.
link |
02:02:49.960
Yeah, the problem is they all go to sleep at 9 p.m.
link |
02:02:52.400
and wake up at 4 a.m. so we never see them.
link |
02:02:54.400
That's right.
link |
02:02:55.720
No, the circadian community has done an amazing job
link |
02:02:59.200
of figuring out what we need.
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02:03:02.840
And then the challenge of course is
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02:03:05.000
making sure that people get what they need
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02:03:07.360
and making sure that at a societal level,
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02:03:09.720
we're not vaulting ourselves into the wrong direction.
link |
02:03:12.120
The biggest problem is that the late waking people,
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02:03:16.440
they think that really,
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02:03:18.200
and I'm going to try to put it in a better way now,
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02:03:20.680
they think, oh, because you're a morning person,
link |
02:03:22.680
you want to see the sun early,
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02:03:24.120
so you want me to suffer it dropping late.
link |
02:03:27.280
But that's not the case,
link |
02:03:29.040
because what happens is when they shift it back
link |
02:03:32.760
after the daylight saving,
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02:03:34.640
now they're going to make you suffer really badly
link |
02:03:36.800
because now it's going to be earlier.
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02:03:39.400
Right, in the fall.
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02:03:40.360
In the fall when there's not enough light.
link |
02:03:42.240
If they keep it the same way,
link |
02:03:43.800
so try to convince them that actually this at the end
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02:03:47.280
causes more trouble when you need the light
link |
02:03:50.120
for your late schedule in the fall
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02:03:52.840
when they shift it back.
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02:03:54.440
Then they say keep it daylight saving all the time.
link |
02:03:57.000
And that has been proven.
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02:03:59.200
That is very bad.
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02:04:00.640
Like people have done studies
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02:04:02.160
that literally two areas close to each other's
link |
02:04:05.240
and areas that were the whole year on daylight saving
link |
02:04:08.440
has much more problems,
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02:04:10.520
even in cancer rates and depression.
link |
02:04:12.560
So you don't want to do that.
link |
02:04:14.080
So that's what trying to convince people
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02:04:16.840
that you need to prevent that switch
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02:04:20.240
and you don't need daylight saving at all.
link |
02:04:22.800
That's where the problem happens.
link |
02:04:25.080
Interesting.
link |
02:04:26.160
I had not thought about that,
link |
02:04:27.840
but yes, you late risers that in the fall,
link |
02:04:30.280
when they fall back, as they say,
link |
02:04:32.840
spring forward, fall back, you dial back the clock.
link |
02:04:35.240
It's really compounding the problem that already exists.
link |
02:04:39.520
And it's really nice if you keep it consistent.
link |
02:04:42.360
In the spring, you get the equinox
link |
02:04:45.880
and then the days start going up
link |
02:04:47.920
and then even in the summer start going down
link |
02:04:50.000
and then the fall, you get the other equinox and go back.
link |
02:04:52.440
So it's very symmetrical, right?
link |
02:04:54.640
It goes into short day, longer, long, long, long,
link |
02:04:57.880
then short day again.
link |
02:04:59.440
But now you're getting these bumps
link |
02:05:01.360
in both sides of the spring and fall.
link |
02:05:04.160
Why would you do that?
link |
02:05:05.200
Something that is beautifully symmetrical,
link |
02:05:07.480
beautifully smooth, you're putting bumps into it.
link |
02:05:10.040
Well, and not just beautiful because it's there,
link |
02:05:13.080
but evolved.
link |
02:05:14.880
I mean, essentially this is the system we evolved in
link |
02:05:16.640
for hundreds of thousands of years.
link |
02:05:18.800
Even apart from the exact equator,
link |
02:05:21.320
every part of the earth has seasonality.
link |
02:05:25.240
I want to briefly touch on something
link |
02:05:26.760
which is individual and genetic variation
link |
02:05:29.720
in sensitivity to light.
link |
02:05:31.840
So not chronotype, but first of all, a very basic question.
link |
02:05:37.560
Do people with light eyes, light colored eyes,
link |
02:05:42.240
are they more sensitive to light
link |
02:05:43.760
than people with darker pigmented eyes?
link |
02:05:46.000
I mean, honestly, it makes sense they will be more
link |
02:05:48.640
because if you think of my dark pupil,
link |
02:05:51.320
it's blocking more light.
link |
02:05:52.760
So if you have light pupil, yes, for vision,
link |
02:05:56.640
it may not be very obvious,
link |
02:05:58.000
but for something that is measuring the amount of light,
link |
02:06:00.440
you're getting more light than me.
link |
02:06:02.360
So you'll probably need less light to be effective
link |
02:06:06.320
as somebody who's darker.
link |
02:06:08.600
And that maybe could explain why sometimes lighter people
link |
02:06:11.680
say I don't want to go into very bright conditions
link |
02:06:14.040
because it's really bright.
link |
02:06:15.480
Yeah, I can't even be at a cafe
link |
02:06:18.120
without one of these reflective tables, like a metal table,
link |
02:06:20.800
unless I have very dark sunglasses on.
link |
02:06:22.560
Exactly.
link |
02:06:23.400
It's so bright it's painful for me.
link |
02:06:24.560
Whereas some people like you,
link |
02:06:25.800
we've sat outside and had meals and you're like, fine.
link |
02:06:28.200
I assumed it was kind of Jordanian toughness versus, you know.
link |
02:06:31.280
It's really the pupil blocks more light.
link |
02:06:33.440
So I think it is possible that it's as simple
link |
02:06:36.200
as the pupil blocking more light can have sensitivity.
link |
02:06:39.040
But your question also goes deeper.
link |
02:06:41.480
Are there more sensitivity differences?
link |
02:06:44.520
And my understanding would be,
link |
02:06:45.880
I would think that it may be depends
link |
02:06:48.360
on how effective your cells are in responding to light,
link |
02:06:51.880
how healthy your IPRGC's are.
link |
02:06:54.880
So I would, but there's not many studies to show that.
link |
02:06:58.160
What is really clear that is happening
link |
02:07:00.400
is that patients with bipolar,
link |
02:07:03.480
they seem to have different sensitivities to light.
link |
02:07:06.000
So it seems that at least people
link |
02:07:07.920
who have psychological changes,
link |
02:07:12.360
they may have differences to the sensitivity of light.
link |
02:07:15.400
So.
link |
02:07:17.200
Are those differences in a particular direction?
link |
02:07:20.000
I don't remember the exact.
link |
02:07:21.360
We'll have to, we can look it up.
link |
02:07:22.720
Yeah.
link |
02:07:23.560
Yeah.
link |
02:07:25.400
And people have heard me say this ad nauseum
link |
02:07:27.440
to the point where they actually roll their eyes,
link |
02:07:29.240
but you know that these are the only two pieces of brain.
link |
02:07:32.120
I'm pointing to my eyes folks
link |
02:07:33.320
that are outside the cranial vault.
link |
02:07:35.040
They are two pieces of brain
link |
02:07:36.320
that it basically inform the brain
link |
02:07:38.160
about whether or not to be alert or asleep.
link |
02:07:40.320
Absolutely.
link |
02:07:41.160
But you can imagine that those two little pieces of brain
link |
02:07:43.080
that we call eyes would have genetic variations.
link |
02:07:46.520
Of course, eye color is genetically modular.
link |
02:07:49.200
Is that determined?
link |
02:07:51.520
That there would be genetic variations
link |
02:07:53.280
based on whether or not your ancestry evolved
link |
02:07:55.960
near the equator or further from the equator, right?
link |
02:07:59.020
I mean, you see more blue eyes in Scandinavia
link |
02:08:01.200
than you do in the equator. Absolutely.
link |
02:08:02.040
I mean, it's the lack of light
link |
02:08:03.400
that said you need less inhibition
link |
02:08:06.020
because there's not enough light, right?
link |
02:08:07.620
So that's the idea of the change in color.
link |
02:08:11.480
So yeah, I totally agree with you.
link |
02:08:13.680
I mean, I think this is an area that will be studied later
link |
02:08:16.840
and will be empirically determined.
link |
02:08:19.600
The problem we have in this field right now,
link |
02:08:22.160
which I think is the biggest problem,
link |
02:08:24.360
is we don't have a way to measure
link |
02:08:26.700
the IP RGC sensitivities in humans.
link |
02:08:29.200
So we still, like it's easy to measure your rod cone function
link |
02:08:33.300
if you go to an optometrist.
link |
02:08:35.040
They measure all the details, right?
link |
02:08:36.960
Contrast detection.
link |
02:08:37.800
You look at the chart, you look at the Snellen chart,
link |
02:08:40.400
you look at the letters at the DMV, yeah.
link |
02:08:42.260
But for the non subconscious,
link |
02:08:44.560
we still don't have a good measuring systems
link |
02:08:47.640
to figure out what is Andrew's sensitivity?
link |
02:08:50.600
What is Samer's sensitivity?
link |
02:08:51.920
What is this person's sensitivity?
link |
02:08:53.360
And I think we're starting to work on something like that
link |
02:08:56.560
to hopefully develop these techniques,
link |
02:08:58.320
but till we develop them,
link |
02:09:00.260
it's gonna be very hard to figure out
link |
02:09:02.440
if there is a sensitivity difference,
link |
02:09:04.160
how do they relate on men and women,
link |
02:09:07.560
you know, dark and light and all that,
link |
02:09:10.080
you know, normal versus psychologically effect
link |
02:09:13.240
and stuff like that.
link |
02:09:14.480
Fascinating.
link |
02:09:16.120
And every time you talk, I learned so much.
link |
02:09:19.940
It's like in the best way, the best sense of the term,
link |
02:09:24.440
it's a waterfall of knowledge.
link |
02:09:27.420
As a final question, I have a question about sensitivity
link |
02:09:30.440
of a whole other kind.
link |
02:09:32.500
And that's the sensitivity to spicy food.
link |
02:09:36.520
Now, the reason I'm asking this question,
link |
02:09:38.960
what seemingly out of the blue is that
link |
02:09:41.480
I made the mistake once of having Samer cook for me.
link |
02:09:45.280
And I said, not too spicy.
link |
02:09:48.420
And he said, okay, not too spicy.
link |
02:09:50.640
He actually said, okay, not too spicy.
link |
02:09:52.600
And it almost killed me.
link |
02:09:55.720
Like it was like two or three days.
link |
02:09:57.940
So you know a lot about biology
link |
02:10:00.740
outside the visual system, light, et cetera.
link |
02:10:02.880
You've been around a while.
link |
02:10:05.400
Are there known genetic or inherited
link |
02:10:09.120
of any kind sensitivities to spicy food,
link |
02:10:12.240
to things like red peppers and capsaicin?
link |
02:10:14.200
Because what you call mild,
link |
02:10:17.040
my friend almost put me into the hospital.
link |
02:10:20.440
I think this is similar to you swimming in the ocean
link |
02:10:23.000
and I need to get developed.
link |
02:10:24.440
Okay, true, true.
link |
02:10:25.460
I like cold water swims and Samer's not a fan,
link |
02:10:27.680
but that's going to change.