back to indexTime Perception & Entrainment by Dopamine, Serotonin & Hormones | Huberman Lab Podcast #46
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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,
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and I'm a professor of neurobiology and ophthalmology
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at Stanford School of Medicine.
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Today, we are talking about time perception.
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Our perception of time is perhaps the most important factor
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in how we gauge our life.
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That is, whether or not we think we are being successful,
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whether or not we are failing,
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whether or not we live in fear,
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whether or not we live in relation to things
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in a way that's positive.
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And the reason for that is that our perception of time
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is directly linked to the neurochemical states
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that control mood, stress, happiness, excitement,
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and of course, it frames the way
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in which we evaluate our past.
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So whether or not we think of our past
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as successful or unsuccessful, it frames our present,
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whether or not we think we are on track or off track,
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and it frames our sense of the future,
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whether or not we think we have a bright future,
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a dim future, or whether or not the future
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is very uncertain or not.
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Today, we are going to talk about
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the science of time perception,
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and we are going to talk about tools and protocols
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that you can use that can enhance your ability
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to dilate and contract time.
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What do we mean by dilate and contract time?
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We can control the speed at which we experience life.
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We can slow things down or we can speed
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our experience of life up,
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and we can do that in a very direct and dynamic way.
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It's actually not that hard
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once you understand how time perception works.
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So that's where we're headed.
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I think you're going to come away from today's episode
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with a lot of new knowledge and certainly with many tools
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that you can try in your daily life,
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whether or not that's work, sport, relational,
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emotional, and so on.
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Before we begin our discussion about time perception,
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I'd like to answer some questions that I received
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related to the episode on fasting
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and time-restricted feeding.
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If you haven't seen that episode,
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this information should still be of use to you.
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Time-restricted feeding involves eating
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for a particular period of time in each 24-hour cycle
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that's fairly regular.
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So this would be an eight-hour most often
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or a 10-hour block.
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Some people do shorter feeding windows,
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but regardless, that feeding window is supposed to fall
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at more or less the same period within each 24-hour day.
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This has a number of positive effects on gene expression
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that regulate a number of positive effects
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on the different tissues of the body.
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And for some people, not all,
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but for some people makes weight loss easier
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because of the way that they are not eating
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for large periods of each 24-hour cycle.
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In any event, one of the major questions I got
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after that episode was do supplements break a fast?
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And during that episode,
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I talked about what breaks a fast is highly contextual.
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It basically boils down to whether or not
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something you ingest, whether it be liquid or food,
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increases your resting blood glucose,
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how much it increases that resting blood glucose,
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and how long that increase lasts.
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So you can check out the episode
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for more about what breaks a fast,
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but to address this issue about supplements
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and whether or not supplements a particular break a fast,
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many of the questions were about Athletic Greens.
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Athletic Greens is a sponsor of this podcast.
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It is also a terrific supplement that I had been taking
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for more than a decade before this podcast launched.
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And many people have been using
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and continue to use Athletic Greens.
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Does Athletic Greens break a fast?
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Well, that will somewhat depend on whether or not
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your resting blood glucose tends to run high or low.
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But for most people, including me,
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because I've measured it,
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ingesting Athletic Greens does not break a fast.
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And if it happens to break a fast,
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it would be a very transient break in fast.
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So without knowing your resting blood glucose levels
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on an individual basis,
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there's no way I can say for sure
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that it doesn't break a fast,
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but chances are it does not
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because it doesn't contain much carbohydrate or sugar,
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and it doesn't tend to therefore pull you out
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of the molecular milieu
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associated with low blood glucose states.
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The other question I get is whether or not
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things like fish oil break a fast.
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And once again, this will be contextual,
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but because fish oil is a fat,
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mainly essential fatty acids, in particular EPA and DHA,
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those don't tend to raise blood glucose very much.
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In my case, having measured,
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using a continuous glucose monitor,
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my resting blood glucose, fish oil,
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does not in any way change my resting blood glucose.
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Chances are it won't do that for most people as well.
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So does fish oil break a fast?
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Chances are it does not.
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And of course, people wanted to know
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about pill type supplements,
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caffeine and things that raise dopamine
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and their vitamins and minerals.
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In general, if something doesn't contain sugar
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or much carbohydrate of any kind,
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it's not going to raise blood glucose very much.
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Now, of course, protein can raise blood glucose
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and fat can too as well, although to a lesser extent.
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So again, this is all contextual,
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but at least by the logic that I just spelled out,
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athletic greens, fish oil, and most forms of supplements,
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provided they don't have any sugar or protein content,
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should not quote unquote break a fast.
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Before we begin, I'd like to emphasize
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that this podcast is separate
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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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I'd like to thank the sponsors of today's podcast.
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Our first sponsor is Roca.
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Roca makes eyeglasses and sunglasses
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that are of the absolute highest quality.
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I've spent a lifetime working on the visual system.
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And one of the key things about our visual system
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is that it's designed so that when you move into areas
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where it's sunny or where there are shadows,
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you can still see things with crystal clarity.
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Many sunglasses out there have the problem
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that you have to keep taking them off
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and putting them back on depending on the overall
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so-called ambient environment that you're in.
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Roca sunglasses have solved this problem.
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And their eyeglasses also have superb clarity
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regardless of overall ambient lighting, as we say.
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In other words, you see everything very clearly
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no matter where you are.
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They also come in a number of different styles.
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The aesthetics are really terrific.
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So unlike a lot of performance glasses out there
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that make people look like cyborgs,
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you can wear them anywhere.
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You can wear them to dinner,
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you can wear them to school or work or in social engagements,
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and you can wear them running and cycling
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and out doing your various activities.
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If you'd like to try Roca glasses,
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you can go to Roca, that's R-O-K-A.com,
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and enter the code Huberman to save 20% off your first order.
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Today's episode is also brought to us by Athletic Greens.
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Athletic Greens is an all-in-one vitamin mineral
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I started using Athletic Greens way back in 2012,
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and so I'm delighted that they're sponsoring the podcast.
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The reason I started using Athletic Greens
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and the reason I still take Athletic Greens
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once or twice every day is that it covers
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all of my foundational needs for vitamins,
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minerals, and probiotics.
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In fact, when people ask me what supplements
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they should take, if I were going to recommend
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just one supplement, it would be Athletic Greens
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because of the enormous number of biological factors
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that it impacts in a positive way.
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As I mentioned, vitamins and minerals,
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the probiotics are really important
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for the gut microbiome and gut health,
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which is important for the immune system
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and for brain health and for mood
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and a number of other important factors,
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including hormones and so on.
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If you'd like to try Athletic Greens,
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you can go to athleticgreens.com slash Huberman
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to claim their special offer.
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They'll give you five free travel packs,
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which make it really easy to mix up Athletic Greens
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while you're on the road or in the car,
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and they'll give you a year supply of vitamin D3K2.
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Vitamin D3 and K2 have been shown to be really important
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for a number of important aspects
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of your immediate and long-term health,
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including blood lipid profiles and a number of other things.
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Again, go to athleticgreens.com slash Huberman
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to get the Athletic Greens, the five free travel packs,
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and the year supply of vitamin D3K2.
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Today's podcast is also brought to us by Inside Tracker.
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Inside Tracker is a personalized nutrition platform
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that analyzes data from your blood and DNA
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to help you better understand your body
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and help you reach your health goals.
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I've long been a believer in getting regular blood work done
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for the simple reason that many of the factors
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that impact your immediate and long-term health
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can only be analyzed from a quality blood test.
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And it's for that reason that I get my blood work done
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once every four to six months.
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Might seem like a lot, but it has been vital
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in order to keep my health where I want it
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and to ensure that my health trajectory
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is heading in the direction that I'd like it to go
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with each passing year.
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The other thing about Inside Tracker is they have DNA tests
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which can tell you about the specific makeup of your genes
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that can impact your particular nutrition, lifestyle,
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and supplementation regimes that can also help you
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steer your immediate and long-term health
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in the direction that you want to go.
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They make the whole thing very, very easy.
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You can have the blood test taken at home,
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or you can go to a local clinic.
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Then the results come back.
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And the wonderful thing is the platform,
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the dashboard that they use, walks you through your data
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and points to specific things related to nutrition.
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Maybe you should be eating more of certain things,
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eating less of others,
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supplementing in certain ways or not,
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and lifestyle factors like exercise
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in order to bring the numbers into the ranges
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that are right for your immediate and long-term health.
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If you'd like to try Inside Tracker,
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you can visit insidetracker.com slash Huberman
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to get 25% off any of Inside Tracker's plans.
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Just use the code Huberman at checkout.
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So let's talk about time perception.
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And the most fundamental aspect of time perception
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is something called entrainment.
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Entrainment is the way in which your internal processes,
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your biology and your psychology,
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are linked to some external thing.
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And the most basic form of entrainment
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that we are all a slave to all year round
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for our entire life are so-called circannual rhythms.
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We have neurons, nerve cells in our eye, in our brain,
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and in our body that are marking off
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the passage of time throughout the year,
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literally a calendar system in your brain and body.
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And the way this works is beautifully simple.
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Light seen by your eyes inhibits,
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meaning it reduces the amount of a hormone
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released in your brain called melatonin.
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Melatonin has two major functions.
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One function is to make you sleepy at night,
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and the other is to regulate some of the other hormones
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of the body, in particular, testosterone and estrogen.
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When we view light,
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we reduce the amount of melatonin released.
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In fact, if you wake up in the middle of the night
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when melatonin typically is pretty high
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in your brain and body,
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and you flip on a bright light in the bathroom,
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your melatonin levels crash down to almost zero
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Light is a very powerful modulator of melatonin,
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and light inhibits melatonin.
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Throughout the year, depending on where you live,
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day length varies, and as a consequence,
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the amount of light from the sun
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that is available to you varies.
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So when days are long,
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the amount of melatonin in your brain and body
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that's released tends to be less.
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There's less of it,
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and it's released for shorter amounts of time, okay?
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Because light inhibits melatonin.
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When days are very short,
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the amount of melatonin that's released
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and the duration that that melatonin exists
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in your brain and body tends to be much longer.
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So melatonin correlates with day length,
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and if we are viewing more light,
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we have less melatonin, we view less light,
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we have more melatonin.
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You see different amounts of light each day,
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but we have a process in our brain and body
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that averages the amount of light that you're seeing,
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both from artificial sources and from sunlight,
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and measures that off, and it's so exquisitely precise
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that for a given, say, eight-hour day in the spring,
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because spring in the Northern Hemisphere or elsewhere,
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days are getting longer,
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that means that the amount of melatonin
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is getting progressively less and less,
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and that signal is conveyed to all the systems
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of your brain and body, and this is why most people,
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not all, but most people,
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feel like they have more energy in the spring.
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Conversely, when you have an eight-hour day in the winter,
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the amount of melatonin that corresponds
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to that eight-hour day
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is getting progressively greater and greater,
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Days are getting shorter,
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so melatonin is increasing from day to day to day.
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Every cell and system of your body pays attention to this,
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and as a consequence, most people, not all,
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but most people feel they have a little less
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or sometimes a lot less energy
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and a slightly lower mood in the winter months.
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Now, there are exceptions to this, of course,
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but the melatonin signal is the way
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in which your internal state, your mood,
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your sense of energy, even your appetite,
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is entrained, is matched to some external event.
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In this case, the event is the rotation
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of the Earth around the sun.
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There are other forms of entrainment,
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meaning the matching of your brain and body
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to things that are happening in your external environment.
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One particularly interesting example of this
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was published last year by Perik et al. in Cell Report,
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Cell Press Journal, excellent journal,
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showing that across the calendar year,
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the amount of testosterone and estrogen
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that human beings make varies,
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such that in longer days,
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they tend to make more testosterone and estrogen
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than in shorter days,
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and this was correlated with things like
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desire to seek out romantic partners
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or have romantic interactions with their existing partners,
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even aggression, although not violent aggression,
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but sense of kind of willingness to argue
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and to get into kind of combative states
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and overall energy and mood.
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This is something that had been hypothesized
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for a long time, but it had never really
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been cleanly demonstrated,
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and what they showed was that it's actually the skin
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that's taking information about the amount of light
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and converting it into these increases
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in testosterone and estrogen.
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Light exposure to the skin turns out about two hours a day.
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This was sunlight, in this case, to the upper body.
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These people weren't naked.
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They were wearing clothes, but their arms were exposed.
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Their upper back and neck and face were exposed.
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They were not wearing hats.
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Resulted in large increases,
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significant increases in testosterone and estrogen.
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Now, you could probably export a tool from that
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That's not really what this podcast is about,
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but it's very clear that because the skin is acting
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as an endocrine organ, excuse me,
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as kind of a hormone influencing organ,
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that getting light on the skin, not just to the eyes,
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can influence our sense of wellbeing
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by these hormone pathways.
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And the threshold there, again,
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seemed to be about two hours a day.
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It doesn't have to be very bright outside.
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There can be cloud cover and so on.
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Many people will probably ask,
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will sunscreen inhibit this effect?
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And it doesn't appear that it does.
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Obviously, prioritize skin health and avoiding skin cancer.
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Sunscreen is kind of a controversial topic nowadays.
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Maybe the topic for another podcast episode at some point.
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But nonetheless, what the Perik et al study shows,
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and that's most relevant to today's podcast,
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is that we are entrained,
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we are matched to the external light-dark cycle.
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And as the day length changes, our hormones change.
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And we can override that with exposure to bright lights.
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You know, people go sit on tanning beds.
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It's not a practice I particularly myself engage in,
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but you know, there are a number of different ways
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that people can override these processes.
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But the point is very simple.
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The point is that our perception of time is both conscious,
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you know, it's waiting, watching the clock tick down,
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and there are these slower, what we call oscillatory,
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meaning up and down, repeatedly slower oscillatory events
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related to day length that are influencing our hormones,
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like melatonin, testosterone, and estrogen,
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and therefore our mood, our outlook,
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and even our behavior.
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The next level of time, or bin of time, as we say,
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that we are all entrained or matched to
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is the so-called circadian time cycle,
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which is 24-hour rhythm.
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This is perhaps the most powerful rhythm that we all contain
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and that none of us can escape from.
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We all have this circadian clock
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that resides over the roof of our mouth,
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the cells in that circadian clock fire,
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meaning they release chemicals into our brain and body
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on a very regular rhythm.
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So across the 24-hour cycle,
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they will be very active at some periods
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and less active at others.
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Not surprisingly, there are periods of every 24-hour cycle
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when we are very active and we tend to be alert,
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and others when we are asleep.
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Now, I've talked a lot about circadian rhythms and sleep
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on this podcast previously,
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and so I don't want to repeat too much of that information
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in detail, but I'm just going to give a summary
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of how circadian entrainment works
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because I haven't really covered that
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in the context of time perception.
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We have this circadian clock.
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It goes up and down once every 24 hours and then repeats.
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Every cell of our body has a 24-hour oscillation
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in the expression of various genes.
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How that works is actually really simple,
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elegant, and interesting.
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DNA genes make RNA.
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RNA is converted into proteins.
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Every cell in our body has this beautiful 24-hour timer
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where a gene is expressed,
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and the important thing to understand about a given gene
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in this context is that that gene is inhibited,
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meaning it's reduced by a particular protein,
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by a little biological molecule in that cell.
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So the gene gets expressed when there's very little
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of that other molecule around.
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DNA then becomes RNA.
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RNA is translated into a protein,
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and that protein goes way, way up, and the gene shuts down,
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but as that protein gets used up
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and its levels eventually drop low, low, low, low, low
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to zero, the gene cycle kicks in again,
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and the gene gets expressed.
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The RNA gets expressed in the protein again.
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This all happens on a 24-hour cycle,
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so it's a little built-in timer in each and every one
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of our cells, and I didn't list off the genes,
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but for the aficionados out there,
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they go by names like per, for period, bmal, clock,
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and all these different things.
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We call them the clock genes,
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and those clock genes regulate
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a number of different functions.
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So every cell in our body has a 24-hour cycle
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of gene and protein expression,
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and the earth rotates once every 24 hours,
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and the processes that are happening
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in every cell of our body are linked.
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They are entrained, as we say,
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to the outside light-dark cycle because morning sunlight,
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evening sunlight, and the lack of light
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in the middle of the night make sure that the changes,
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these oscillations that are occurring within the cells
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of our brain and body are matched
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to the outside light-dark cycle.
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And I want to go into all the details of how that happens,
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but there's some very simple tools that one can use
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to ensure that your entrainment,
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your circadian entrainment is precise.
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And I cannot emphasize enough how important it is
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that your circadian entrainment be precise.
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Because disruptions in circadian entrainment
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cause huge health problems.
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They increase cancer risk.
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They increase obesity.
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They increase mental health issues.
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They decrease wound healing.
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They decrease physical and mental performance.
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They disrupt hormones.
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You want your cells to be linked to the circadian cycle
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that's outside you.
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And the circadian cycle outside you mainly consists
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of when there's sunlight and when there is not.
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And that's why the simple protocols to fall out
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of this whole discussion about circadian entrainment
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are the following.
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View 10 to 30 minutes of bright light, ideally sunlight,
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within an hour of waking,
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assuming that you're waking early in the day,
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especially you wake up early in the day,
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get outside, see sunlight.
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Do that again in the afternoon or around evening,
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10 to 30 minutes, depending on how bright it is outside.
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Artificial lights throughout the day,
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or if you want to be awake and you wake up early
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and there's no sunlight outside,
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you can of course turn on artificial lights
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if you want to be awake.
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But basically you want as much bright light,
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ideally from sunlight, coming in through your eyes
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throughout the day.
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And then in the evening,
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you want as little bright light coming in
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through your eyes.
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I've said this over and over and over again on this podcast.
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There's always a lot of negotiations,
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but I want to make a few things clear.
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Try not to wear sunglasses if you can do it safely.
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Find to wear eyeglasses or contacts.
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That's not going to be a problem.
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The light viewing that you do
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and the avoidance of light at night,
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set the fundamental layer of your time perception.
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One of the best ways to disrupt your perception of time
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in the ways that we're going to talk about
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in the subsequent portions of the podcast
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is to disrupt your circadian clock.
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And that is not a good thing
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for a number of different reasons.
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There are other ways to so-called
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entrain your circadian clock.
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One of the best ways to do that
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is to engage in physical activity
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at fairly regular times of day.
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You don't have to do it every day,
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but if you're going to exercise,
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try and exercise at a fairly consistent time of day.
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Probably better to exercise than to not exercise,
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even if you have to move that time of day.
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But light, activity,
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and we'll talk about the third in a minute, food,
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are the major ways that you entrain
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your internal perception of time
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to the external events of the world,
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meaning that the turning of the earth
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and therefore the exposure to sunlight or not.
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So in addition to the sunlight viewing
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in the morning and throughout the day
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and avoiding bright light at night of any kind,
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not just blue light,
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trying to get your activity,
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your exercise at fairly regular
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within plus or minus two hours from each day to the next
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is going to have a very positive effect
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on so-called circadian entrainment.
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And also eating at fairly regular times.
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However, this is exciting.
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The data mainly point to the fact
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that you need to eat
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within more or less the same time window each day,
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not that you always need to eat your meals
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at exactly the same time.
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So you don't necessarily have to eat lunch at noon
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and a snack at four and dinner at eight
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in order to keep your circadian entrainment
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You could, for instance, have a small snack at noon
link |
and then eat at two and then have dinner at six
link |
and then a small snack at eight.
link |
It doesn't so much matter when the exact meals fall
link |
so much as that they fall more or less
link |
within a consistent period or phase of each 24 hour cycle.
link |
What happens when this circadian clock
link |
starts getting disrupted?
link |
I mean, this is after all an episode about time perception.
link |
It's not an episode about circadian rhythms and entrainment.
link |
Well, there's a classic study by Ashoff done in 1985
link |
that's now been repeated many times
link |
where they had people go into environments
link |
where they didn't have clocks and they didn't have windows
link |
and they didn't have watches.
link |
And they were sometimes even in constant dark
link |
or constant light.
link |
And they evaluated how well people perceive
link |
the passage of time on shorter timescales.
link |
And what they found was really interesting.
link |
What they found is that people underestimate
link |
how long they were in these isolated environments.
link |
So after 42 days or so, they'd ask people,
link |
how long do you think you've been in here?
link |
And people would say 28 days or 36 days.
link |
They generally underestimated how long they had been
link |
in this very odd environment with no clocks or watches
link |
or exposure to sunlight or regular rhythms
link |
of artificial light.
link |
In addition, they found that their perception
link |
of shorter time intervals was also really disrupted.
link |
So if they asked them to measure off two minutes,
link |
normally people are pretty good
link |
at measuring off two minutes.
link |
People come within five to 15 seconds at most.
link |
If you kind of had to sit there and just wait,
link |
you have a pretty good idea of when two minutes is up,
link |
you say two minutes is up.
link |
Well, when people's circadian clocks
link |
or circadian entrainment, I should say, was disrupted,
link |
their perception of time measurement on shorter timescales
link |
of minutes or even seconds was greatly disrupted.
link |
And as we'll see in a couple of minutes,
link |
that actually causes great problems
link |
for how you contend with work,
link |
how you contend with challenges of different kinds.
link |
You want your circadian entrainment to be pretty locked in
link |
or pretty entrained to the outside light-dark cycle
link |
so that your perception of time
link |
on shorter time intervals can be precise
link |
because the ability to perceive time accurately
link |
for the given task or given thing that you're involved in
link |
turns out to be one of the most fundamental ways
link |
that predicts how well or poorly you perform
link |
that thing or task.
link |
So we've talked about circadian entrainment,
link |
the matching of the cells and tissues
link |
and organs of our body to the 365-day journey
link |
that the earth takes around the sun each year.
link |
And we talked about circadian entrainment,
link |
the way that the 24-hour genetic and protein clocks
link |
of each and every one of our cells is matched
link |
to the rotation of the earth on its axis
link |
and the exposure or lack of exposure to the sun
link |
because of that rotation on its axis.
link |
Next, I'd like to talk about so-called
link |
ultradian entrainment.
link |
Ultradian rhythms are rhythms of about 90 minutes or so,
link |
and all of our existence is broken up
link |
into these 90-minute ultradian cycles.
link |
When you go to sleep at night,
link |
whether or not you sleep six hours or four hours
link |
or eight hours or 10 hours,
link |
that entire period of sleep is broken up
link |
into these 90-minute ultradian cycles.
link |
Early in the night, you tend to have more slow-wave sleep.
link |
Later in the night, you tend to have more REM sleep,
link |
but nonetheless, your sleep is broken up
link |
into these 90-minute cycles.
link |
However, when you wake up in the morning,
link |
many of the things that you do are governed
link |
by these ultradian rhythms.
link |
For instance, if you were to work,
link |
meaning do math or try and learn a language
link |
or do physical work of any kind or work out,
link |
the 90-minute time block seems to be the one
link |
in which the brain can enter a state of focus and alertness
link |
and do hard work and focus, focus, focus,
link |
and then at about 90 minutes,
link |
there's a significant drop in your ability
link |
to engage in this mental or physical work.
link |
Now, everybody from the self-help literature
link |
to the business literature to the pop psychology literature
link |
has tried to leverage these ultradian cycles
link |
by saying if you're going to do something hard
link |
and you want to focus on it,
link |
limit it to 90 minutes or less,
link |
and I am one of those people
link |
who's also joined that conversation,
link |
and indeed, I use 90-minute work cycles,
link |
and I think they are extremely powerful.
link |
One should never expect that you're going to drop
link |
immediately into a state of high focus at the beginning
link |
and then remain there for 90 minutes.
link |
We all struggle to varying degrees to achieve focus
link |
and motivation and drive within those 90-minute cycles,
link |
but it is true, meaning there is ample literature
link |
to support the idea that after about 90 minutes,
link |
we tend to go into a state of less ability to focus.
link |
So while this isn't time perception per se,
link |
it is, again, an example of entrainment.
link |
What are we in training to, right?
link |
Just because we can focus for 90 minutes
link |
and then not so well at 100 minutes or 120 minutes,
link |
what are we in training to?
link |
Well, what you're in training to
link |
is the release of particular neurochemicals,
link |
in this case, acetylcholine and dopamine,
link |
that allow your brain to focus
link |
for particular periods of time, 90 minutes or so,
link |
and after about 90 minutes or so,
link |
the amount of those chemicals that can be released
link |
tends to drop very low,
link |
which is why your ability to focus becomes diminished.
link |
If one would like to explore more about the kind of backbone
link |
and basis of these ultradian rhythms,
link |
it goes by a different name.
link |
This was originally called the basic rest activity cycle.
link |
This was proposed many years ago by Nathaniel Kleitman.
link |
It was established to be true within sleep states,
link |
as I mentioned before.
link |
Then it was debated for a long time
link |
whether or not these 90-minute cycles
link |
also control our ability to focus
link |
and perform work in wakeful states,
link |
and it turns out that they do.
link |
Now there's a lot of literature to support that.
link |
I always get the question,
link |
how do you know when the 90-minute cycle begins?
link |
In other words, let's say you wake up at 8 a.m.
link |
and you just finished a 90-minute sleep cycle.
link |
Does that mean that your next 90-minute cycle
link |
where you could do work begins right at 801?
link |
The interesting thing about these basic rest activity cycles,
link |
these ultradian rhythms,
link |
is that you can initiate them whenever you want.
link |
This is not like a circadian rhythm,
link |
which is a hardwired, unerring signal of 24 hours.
link |
The ultradian rhythms that occur during sleep
link |
are hardwired, unerring.
link |
You don't get the option of making your sleep cycles
link |
at 120 minutes or five minutes.
link |
You don't get that option.
link |
But if you decide that you want to apply
link |
ultradian rhythms to work and performance,
link |
you can set a clock and decide,
link |
okay, now the focus begins, now the work begins,
link |
and this 90-minute cycle is the period
link |
in which I'm going to do work.
link |
And I actually do this.
link |
Mid-morning and sometimes twice a day,
link |
I do a 90-minute cycle where I limit all distraction
link |
as much as possible, put away my phone,
link |
often turn off the internet as well.
link |
I talked about this in an episode
link |
on kind of an optimal work day,
link |
at least for me, just to give an example
link |
of how this might work.
link |
But I want to emphasize again
link |
that these ultradian rhythms are ones that you set.
link |
So you decide I'm going to work for 90 minutes.
link |
What you can't negotiate, however,
link |
is that at about 100 minutes or 120 minutes,
link |
no matter who you are,
link |
you're going to see a diminishment in performance.
link |
You're not going to focus as well.
link |
And that's, again, because of the way
link |
that these 90-minute cycles are linked
link |
to the ability of the neurons
link |
that release acetylcholine and dopamine
link |
and to some extent norepinephrine,
link |
the things that give us narrow focus, motivation, and drive,
link |
the way that these 90-minute cycles
link |
are involved in those circuits.
link |
After about 90 minutes,
link |
those circuits are far less willing to engage,
link |
and therefore it's much harder
link |
to continue to focus to a high degree.
link |
Some people like to do multiple 90-minute cycles
link |
In that case, you need to separate them out.
link |
You can't do one 90-minute cycle
link |
then go right into another 90-minute cycle
link |
then another 90-minute cycle.
link |
You can't cheat these circuits related to acetylcholine
link |
and dopamine and norepinephrine, unfortunately.
link |
I suggest that people do no more than three,
link |
and ideally it would be two
link |
or just one of these 90-minute cycles.
link |
Why did I say ideally?
link |
Well, they are very taxing.
link |
You are in a very narrow tunnel of focus.
link |
So for me, I can do one mid-morning.
link |
I can probably do another one in the afternoon.
link |
This is not the kind of work that's like checking email
link |
or text messaging or social media.
link |
This is very focused, hard work.
link |
Working on hard problems of various kinds,
link |
and this will be different for everybody.
link |
So I recommend that they be spaced
link |
by at least two to four hours,
link |
and most people probably won't be able to handle
link |
more than two per day.
link |
There are probably some mutants out there
link |
that could do three or four, but that's exceedingly rare.
link |
I think even one a day is going to feel
link |
like a significant mental investment,
link |
and afterwards, you're going to feel pretty taxed.
link |
So now we've talked about circannual,
link |
circadian, and ultradian rhythms,
link |
but we haven't really talked about time perception per se.
link |
We've mainly talked about the subconscious,
link |
slow oscillatory ways in which we are entrained
link |
or matched to the year or to the day,
link |
and these ultradian cycles that we can impose on our work
link |
and that we can leverage toward more focus if we like.
link |
But what about the actual perception of time?
link |
What actually controls how fast
link |
or how slowly we perceive time going by?
link |
There are basically three forms of time perception
link |
that we should all be aware of.
link |
One is our perception of the passage of time in the present,
link |
how quickly or slowly things seem to be happening for us.
link |
This is kind of like an interval timer, ticking off time,
link |
tick, tick, tick, tick, tick, tick.
link |
It's either fine slicing like that or tick, tick, tick.
link |
We have interval timers.
link |
I'll discuss the basis of those interval timers.
link |
We also engage in what's called prospective timing,
link |
which is like a stopwatch, measuring off things
link |
as they go forward.
link |
That might sound a little bit like what I just described,
link |
but it's actually a little bit different.
link |
For instance, if I told you to start measuring off
link |
a two-minute time interval into the future,
link |
you could do that pretty well.
link |
But if I told you you had to measure
link |
a five-minute time interval into the future
link |
and you couldn't use any clocks or watches
link |
or your phone or anything like that,
link |
you would have to set the tick marks.
link |
You would have to decide how many times
link |
you were going to count off
link |
during that five-minute time block.
link |
There's also retrospective time,
link |
which is how you measure off time in the past.
link |
So if I say, you know, last week I know you went
link |
to the park, you did some things with friends,
link |
you know, you went out in the evening.
link |
How long was it between lunch
link |
and when you went to dinner with friends?
link |
You probably then go, okay, well, I remember
link |
I went to dinner at seven and we had lunch right around two.
link |
You're using memory to reconstruct certain sets
link |
of events in the past and get a sense
link |
of their relative positioning within time, okay?
link |
So we have retrospective, current time interval
link |
measurements, and then prospective time measurement
link |
The beauty of time perception in the human nervous system
link |
is that it boils down to a couple of simple molecules
link |
that govern whether or not we are fine slicing time
link |
or whether or not we are batching time in larger bins.
link |
Those molecules go by names that maybe you've heard,
link |
things like dopamine and norepinephrine,
link |
neuromodulators, called neuromodulators
link |
because they modulate, they change the way
link |
that other neural circuits work.
link |
Also things like serotonin.
link |
Serotonin is released from a different site in the brain
link |
than dopamine and norepinephrine is
link |
and has a different effect on time perception.
link |
So just to give you an example of how things like dopamine
link |
and serotonin can modulate our perception of time,
link |
I want to focus on a little bit of literature
link |
that now has been done, unfortunately,
link |
in animals and humans, and which essentially shows
link |
that the more dopamine that's released into our brain,
link |
the more we tend to overestimate the amount of time
link |
that has just passed.
link |
Let me repeat that.
link |
The more dopamine that is released into our brain,
link |
the more we tend to overestimate how much time has passed.
link |
These experiments are very straightforward, excuse me,
link |
and they're very objective, which is really nice,
link |
which is you can give people or an animal a drug
link |
that increases the amount of dopamine
link |
and then ask them to measure off
link |
without any measurement device like a watch or a clock
link |
when one minute has passed.
link |
As dopamine levels rise in the brain,
link |
people tend to think that the minute is up before a minute.
link |
So at the 38-second mark, they'll say,
link |
okay, I think a minute is up.
link |
So they've overestimated how much time has passed, okay?
link |
The higher the level of dopamine,
link |
the more people tend to overestimate.
link |
Now, it's also true that norepinephrine,
link |
also called noradrenaline, plays a role,
link |
and its role is very similar to that of dopamine.
link |
And that's because norepinephrine and dopamine
link |
are close cousins.
link |
As some of you may recall,
link |
that they are actually manufactured from one another, okay?
link |
So dopamine can actually make epinephrine and norepinephrine
link |
There's a cascade in which dopamine can be made
link |
into norepinephrine and epinephrine, which is remarkable.
link |
How does having elevated levels of dopamine
link |
and norepinephrine cause one to overestimate
link |
how much time has passed?
link |
Well, it does it because of the way
link |
that it causes fine slicing of your time bins.
link |
So fine slicing of time bins is like increasing
link |
the frame rate on your camera, right?
link |
Slow motion is achieved in movies and elsewhere
link |
by increasing the frame rate.
link |
So if you take a movie at 30 frames per second
link |
and watch it, it will appear to have a certain speed, right?
link |
Because those are just snapshots, 30 frames per second.
link |
In contrast, if you took that same movie
link |
at 4,000 frames per second, you are fine slicing,
link |
and you're going to see every little detail.
link |
And as you play each one of those frames,
link |
it's going to look like it moved slower, okay?
link |
Whatever, so the kind of jump shot in basketball
link |
that's done slowly, any slow motion is the consequence
link |
of higher frame rate.
link |
So dopamine and norepinephrine increase frame rate.
link |
And as a consequence, they tend to lead us
link |
to overestimate the amount of time that's passed.
link |
Conversely, the neuromodulator serotonin causes people
link |
to underestimate the amount of time that's passed.
link |
So they've done these experiments.
link |
They actually have done these experiments using in humans
link |
with drugs that increase serotonin.
link |
They've also done them with cannabis,
link |
which increases serotonin among other things,
link |
including the cannabinoid receptor activation.
link |
And when people have elevated levels of 5-HT
link |
or whether or not they've ingested cannabis,
link |
they tend to underestimate how much time has passed.
link |
You do the equivalent experiment.
link |
You tell people that they have to guess
link |
or tell you when five minutes, for instance, has passed,
link |
just to use five minutes as an example this time.
link |
And generally they will miss the five-minute mark.
link |
They will think, they'll let six minutes pass
link |
and they'll say, okay, it was five minutes,
link |
and they've underestimated how much time has passed.
link |
And that's because serotonin
link |
and some of the related molecules in the brain
link |
tend to lead to slower frame rates, right?
link |
They take the frame rate from, in the example I used before,
link |
from 4,000 frames per second
link |
down to say 20 frames per second.
link |
So this is very interesting.
link |
It's interesting in terms of how pharmacology can be used
link |
to adjust time perception,
link |
but it's also interesting in the context
link |
of that circadian rhythm.
link |
There's some emerging evidence
link |
that throughout the 24-hour cycle,
link |
there are robust changes
link |
in the amount of dopamine, norepinephrine, and serotonin
link |
that are present in the brain and bloodstream and body,
link |
depending on time of day within the circadian cycle.
link |
Now, I'm not talking about during sleep.
link |
During sleep, there are definitely variations
link |
in things like dopamine, norepinephrine, and serotonin.
link |
I talked about that in the episodes on sleep.
link |
Here, I'm just talking about the role of these molecules
link |
in time perception during wakefulness.
link |
So much of the evidence points to the fact
link |
that in the first half of the day,
link |
approximate first half of the day,
link |
dopamine and norepinephrine are elevated
link |
in the brain, body, and bloodstream
link |
much more than is serotonin.
link |
And that in the second half of the day,
link |
and in particular towards evening and nighttime,
link |
serotonin levels are going up.
link |
I think that's fairly well-established now.
link |
What that means, based on what we just discussed
link |
about the role of dopamine, norepinephrine, and serotonin
link |
in setting the frame rate of time perception,
link |
is that our perception of the passage of time
link |
will be very different in the early part of the day
link |
and in the latter half of the day.
link |
And there's starting to be some evidence to support this,
link |
that early in the day, people tend to overestimate
link |
how much time has passed.
link |
And later in the day, they tend to underestimate
link |
how much time has passed.
link |
And this is independent of taking any kind of substance
link |
that would increase or decrease dopamine or serotonin.
link |
Now, this is important in terms of how one thinks
link |
about structuring their day,
link |
because I know many people are thinking about
link |
the various tasks that they need to do
link |
throughout their day.
link |
Many, or I should say all of the literature at least
link |
that I can find on productivity and things of that sort
link |
point to the idea that we should be doing the hardest task,
link |
the thing that we want to do the least
link |
or the most important task early in the day
link |
as a kind of a psychological tool for getting it done
link |
and feeling as if we accomplished something.
link |
And I think that's an excellent protocol, frankly.
link |
But I'm not sure it's an excellent protocol
link |
because of the way that we sense accomplishment,
link |
or at least it's not only an excellent protocol
link |
because of the way that we sense accomplishment.
link |
Another reason to move something that's very hard
link |
into the early part of the day
link |
is that if indeed the dopaminergic and noradrenergic circuits
link |
are more active at that time,
link |
we are actually in a better position cognitively
link |
to parse that hard problem
link |
because of the way that we are able to fine slice
link |
our perception of time
link |
and fine slice all the perceptual events outside us.
link |
So what I'm really saying is that early in the day
link |
you are a much more high resolution camera, so to speak,
link |
than you are later in the day.
link |
Now, different types of tasks and different types of things
link |
require different frame rates
link |
or different ways of perceiving time.
link |
And indeed this also lends itself to a tool
link |
whereby for activities that involve
link |
more kind of creative thinking
link |
that aren't as constrained by particular answers or outcomes
link |
and in which we need to kind of blend
link |
different aspects of our memory,
link |
different aspects of task utilization.
link |
In other words, for creative works, for brainstorming,
link |
for things that are a bit more fluid, so to speak,
link |
the more serotonergic second half of the day
link |
and because of the way the serotonergic
link |
second half of the day lends itself to our time perception
link |
may actually be more beneficial for those sorts of tasks.
link |
And I'll put a reference to a couple of the studies
link |
that point to this idea
link |
that in these higher dopaminergic states,
link |
we are better at doing certain sorts of tasks.
link |
And in these more serotonergic states
link |
we're better at doing other sorts of tasks
link |
and how the dopamine tends to be earlier in the day
link |
and the serotonin later in the day, so to speak.
link |
These are broad, I'm painting with broad strokes here,
link |
but I think these lend themselves
link |
to some really excellent tools
link |
because I think we all understand the value
link |
of doing something that's hard or challenging
link |
but we should ask ourselves harder challenging how?
link |
What does that task actually really require
link |
in terms of time perception?
link |
Some people might appreciate some examples
link |
of how this might work.
link |
Basically what I'm saying is
link |
if you are doing work that involves
link |
adhering to some rigid rules,
link |
so math or a recipe or execution of musical scales
link |
or physical skills or accounting
link |
or something that requires a lot of precision
link |
where there's a right and wrong answer and it's hard,
link |
I would suggest that you do that
link |
in the early part of the day
link |
because of the way that dopamine and norepinephrine
link |
impact time perception.
link |
You are literally better at slicing up time.
link |
You are a higher resolution brain during those times
link |
and so that's going to lend itself better
link |
to events and demands that require high resolution.
link |
Whereas in the afternoon,
link |
in this more of what I'm calling serotonergic state,
link |
that's when you're going to be better at brainstorming
link |
and creative works where there's some flexibility
link |
in terms of how you're batching time and perceiving time
link |
and there isn't so much rigid oversight
link |
of a right or wrong answer.
link |
And as an aside to support what I said,
link |
but also to take us back to this critical role
link |
of the circadian rhythm,
link |
there is a lot of evidence
link |
that when one's sleep is disrupted,
link |
when sleep is either too short or is fragmented
link |
or is not of high enough quality for enough days,
link |
one of the first things to happen
link |
is that there is a dysregulation
link |
of these dopaminergic, neurodegeneric
link |
and serotonergic states throughout the day.
link |
They get kind of mish-mashed up.
link |
It's not that they're a total mess,
link |
but they aren't as cleanly defined.
link |
And I think this is one of the reasons
link |
why when we haven't slept well or we haven't slept enough,
link |
we tend to feel a little off, like we can't concentrate.
link |
Part of that lack of concentration is due to other things,
link |
but part of that concentration could be due to the fact
link |
that our sense of the passage of time is disrupted.
link |
So there seems to be some value
link |
in keeping the dopaminergic, neurodegenergic state
link |
kind of limited to the early part of the day
link |
and the serotonergic state, as we're calling it,
link |
going to push towards the second half of the day.
link |
Now, there is a version of how dopamine and norepinephrine
link |
can impact our perception of the passage of time
link |
in ways that can be very disruptive or even maladaptive.
link |
And the best example that I'm aware of is trauma.
link |
Many people who have been in car accidents
link |
or who have experienced some other form of major trauma
link |
do what's called overclocking.
link |
Overclocking is when levels of dopamine and norepinephrine
link |
increase so much during a particular event,
link |
our level of alertness has increased so much
link |
during a given event that we find slice,
link |
in other words, the frame rate is increased so much so
link |
that we perceive things as happening in ultra slow motion.
link |
Now, that might not seem like a bad thing overall,
link |
but the problem with overclocking is the way
link |
in which that information gets stamped down
link |
into the memory system.
link |
So the memory system, which involves areas of the brain,
link |
like the hippocampus, but also the neocortex,
link |
is basically a space-time recorder.
link |
What do I mean by space-time recorder?
link |
Well, your nervous system, of course,
link |
is housed in the darkness of your skull.
link |
It doesn't have a whole lot of information
link |
about the outside world,
link |
except light coming in through the eyes
link |
and whatever happens to hit our ears
link |
in terms of sound waves and skin and so forth.
link |
So it has to take all those neural signals
link |
and it has to create a record of what happened.
link |
Now, it doesn't create a record of everything that happened,
link |
but car accidents and trauma and things of that sort
link |
oftentimes are stamped down
link |
into our record of what happened.
link |
And what gets stamped down,
link |
what we actually mean by the phrase stamped down,
link |
is that the precise firing of the sequence of neurons
link |
that reflected some event,
link |
so let's say I'm in a car accident,
link |
certain neurons are firing
link |
because of the flipping of the car
link |
or there's screams or there's blood
link |
or things of that sort,
link |
all of that neural activity gets repeated in the hippocampus
link |
and then the sequence of the firing of those neurons
link |
is also remembered.
link |
So it's not just that neuron one, two, three, four
link |
fired in that sequence,
link |
it's also that neuron one, two, three, four
link |
fired at a particular rate.
link |
So it would be one, two, three, four during the actual event
link |
and then the memory is stored
link |
as firing of those neurons as one, two, three, four, right?
link |
If during the event it was one, two, three, four
link |
the storage of the memory is not going to be one,
link |
two, three, four, okay?
link |
In other words, there's both a space code as we say,
link |
meaning the particular neurons that fire is important
link |
and there's a rate code,
link |
how quickly those neurons fire or the relative firing,
link |
the timing of the firing of those neurons
link |
is also part of the memory.
link |
This affords our memory system tremendous flexibility.
link |
What it means is that you can take the same set of neurons
link |
in the hippocampus and stamp down many, many more memories
link |
because all you have to do is use a match
link |
of the different rates of the different neurons
link |
that were firing in order to set that code, right?
link |
Otherwise, if you needed a different set of neurons
link |
for every memory, you need an enormous hippocampus,
link |
you need an enormous head.
link |
So I think you get the basic idea.
link |
Overclocking is a case in which the frame rate is so high
link |
that a memory gets stamped down
link |
and people have a very hard time shaking that memory
link |
and the emotions associated with that memory.
link |
And it's not the topic of today's conversation,
link |
but we will cover trauma in a future episode in detail,
link |
but many of the treatments for trauma, EMDR,
link |
nowadays there's a lot of excitement also
link |
about ketamine therapies, exposure therapies,
link |
like cognitive behavioral therapies,
link |
involve not just trying to reduce the amount of emotion
link |
associated with a memory,
link |
but also a deliberate speeding up
link |
or slowing down of that memory.
link |
In other words, trying to allow the person
link |
who experienced the trauma to take control
link |
of the rate of the experience in their memory,
link |
not just whether or not the memory happened at all.
link |
In fact, one of the first things that trauma victims learn
link |
is that they aren't going to forget what happened.
link |
What's eventually going to happen,
link |
ideally with good treatment,
link |
is that the emotional weight of the experience
link |
will eventually be divorced
link |
from the memory of the experience.
link |
And that's done again by trying to reduce the amount
link |
of emotional activation during the recall of that experience
link |
and one of the best ways to do that
link |
is to alter the rate of the memory playback.
link |
In other words, taking that firing of neurons
link |
that might've been one, two, three, four,
link |
again, it would be much more complicated,
link |
but one, two, three, four for the car crash,
link |
and getting the memory to play back at a rate
link |
of one, two, three, four,
link |
or even one, two, three, four, one, two, three, four.
link |
In other words, allowing the person
link |
or instructing the person to take control
link |
of the rate of the playback.
link |
And in that way, there seems to be
link |
still yet unknown mechanism
link |
by which people can uncouple some of the emotional weight
link |
that's associated with that memory.
link |
So overclocking is a kind of extreme example
link |
of where the dopaminergic and the noradrenergic system
link |
is ramped up so high that people have this,
link |
unfortunately, what seems like indelible mark
link |
in their brain of a particular event.
link |
But again, trauma treatment is designed
link |
to uncouple the emotional load of that event.
link |
Some of you are probably saying, why dopamine during trauma?
link |
I thought dopamine was the feel-good molecule.
link |
Well, in reality, dopamine is not necessarily
link |
a molecule of reward.
link |
It's a molecule of motivation, pursuit, and drive.
link |
And because of the close relationship
link |
between dopamine and norepinephrine,
link |
oftentimes they are co-released.
link |
So whether or not dopamine is released during car crashes
link |
or other forms of trauma, we don't know.
link |
But what we do know is that both the dopamine system
link |
and the noradrenergic system,
link |
when we say noradrenergic, we mean norepinephrine,
link |
those systems are greatly increased
link |
anytime there's a heightened state of arousal.
link |
And arousal can have negative valence,
link |
like a meaning associated with an event that we really hate
link |
that we would prefer not to be involved in,
link |
or it can have positive valence.
link |
But dopamine and norepinephrine
link |
are kind of the common hallmark
link |
of all things of elevated arousal.
link |
And so that's why we see evidence for dopamine
link |
being associated with these changes in time perception,
link |
both for positive events and for negative events.
link |
There's a very interesting relationship
link |
between arousal, dopamine, time perception, and blinking.
link |
And this is all supported by a really interesting paper.
link |
First author Terhune is the last name, T-E-R-H-U-N-E,
link |
is published in Current Biology, Cell Press Journal.
link |
Excellent journal.
link |
The title of the paper is
link |
Time Dilates After Spontaneous Blinking.
link |
So heightened states of arousal
link |
are associated with heightened levels of dopamine.
link |
You now know that dopamine leads
link |
to a kind of fine slicing of time.
link |
And one of the ways that we fine slice time is by blinking.
link |
You know, we think of blinking
link |
as just a thing to like lubricate our eyes
link |
or to limit the amount of light coming into our eyes,
link |
but it's a shutter on our experience.
link |
So much of the information
link |
that coming into the brain through our eyes
link |
impacts our attention.
link |
I've said it before on this podcast
link |
that cognitive attention follows visual attention,
link |
at least for sighted individuals.
link |
Well, it turns out that dopamine and increases in dopamine
link |
are associated with increases in spontaneous blink rate.
link |
So the more aroused we are, the more awake we are.
link |
There are a number of effects,
link |
pupils dilate, heart rate increases, et cetera,
link |
but also blink rate increases.
link |
And every time we blink, this study cleanly shows,
link |
we shift our perception of time,
link |
leading to, as I mentioned before, overestimations of time.
link |
So it seems as though in some way,
link |
blink rate is actually related to frame rate.
link |
And so this is very, very interesting.
link |
And the way that you could think about leveraging this
link |
would be if you wanted to actually slow down
link |
your perception of time, you would blink less.
link |
And if you want to speed up your perception of time,
link |
you would blink more.
link |
Now you'd have to think of a scenario
link |
in which that would be useful to you.
link |
Obviously, if you're going to blink,
link |
you're going to miss things as well.
link |
But I think it's a very interesting parameter
link |
of our visual attention as it relates to time perception,
link |
because what it really speaks to
link |
is that these neuromodulators like dopamine or serotonin
link |
that adjust frame rate,
link |
they're not doing it through some magical mechanism.
link |
In fact, there's no single brain area
link |
that we can say controls time perception.
link |
I haven't said today, oh, you know, it's the striatum.
link |
Well, it involves the striatum,
link |
but I'm not going to say, for instance,
link |
oh, it's the cerebellum.
link |
The cerebellum is definitely involved in timing of movement,
link |
something for a future podcast,
link |
but time perception is what we call a distributed phenomenon.
link |
It's a network of areas in the brain working together,
link |
but dopamine in the way that it relates
link |
to the shuttering of your eyes
link |
seems to be controlling the frame rate on your experience.
link |
Numerous times on this podcast,
link |
I've talked about cold exposure,
link |
and nowadays there's a lot of interest
link |
in things like cold showers, ice baths, submersion
link |
in cold water tanks and, you know,
link |
lakes and oceans and things of that sort.
link |
There are a lot of different positive effects
link |
Provided it's done properly,
link |
it can lead to increases in metabolism, brown fat stores,
link |
which are the good fat stores that you want.
link |
They're sort of like a furnace
link |
that allow you to heat yourself up,
link |
stay warm in cold environments to reduce inflammation,
link |
to increase resilience and so forth.
link |
There's a study published in the European Journal
link |
of Physiology showing that cold exposure
link |
can increase our baseline levels of dopamine robustly, 2.5X,
link |
and it's a long lasting increase in dopamine
link |
and appears to be a healthy one,
link |
meaning it doesn't seem to be addictive.
link |
I'm sure there are some people out there addicted to ice baths
link |
but, you know, when you think about the range
link |
of dopamine inducing behaviors that are addictive,
link |
that seems to be more on the health promoting side.
link |
What's interesting is that because cold water exposure
link |
increases dopamine,
link |
it will also change your perception of time.
link |
And if you've ever done one of these cold water exposures,
link |
you've experienced this,
link |
you've experienced getting in and feeling like,
link |
wow, making it three minutes is a really, really long time.
link |
And you are fine slicing time,
link |
your frame rate is going up.
link |
Part of that, just at a kind of a course level
link |
as you're thinking, this is painful, I don't like this,
link |
I want to get out, right?
link |
But part of it is also that your dopamine levels
link |
are going up very quickly,
link |
and therefore your perception of that discomfort
link |
is also being fine sliced.
link |
And so you could leverage a tool, for instance,
link |
where you try and entrain your thinking
link |
to something other than your immediate experience, right?
link |
This is a kind of a controversy, if you will,
link |
in the cold exposure world.
link |
The question is, do you try and lean into the experience
link |
and really feel it?
link |
Or do you try and distract yourself, you know,
link |
sing a song or count off, you know, from one to 100?
link |
Just know that whatever tactic you use
link |
to get through the cold exposure,
link |
that the dopamine level that's now increased in your system
link |
is going to cause you to fine slice
link |
or experience that at slow motion.
link |
So a minute is going to seem like a lot longer
link |
than a minute in reality.
link |
So you could, for instance, decide to pay attention
link |
to some external cue.
link |
Maybe it's a metronome that ticks once every 10 seconds.
link |
You could decide to think about something else.
link |
You could decide to sing a song in your head
link |
or sing a song out loud.
link |
All of that will divorce you
link |
from the sensation that you're experienced somewhat,
link |
but more so it will divorce you
link |
from the perception of your experience
link |
as governed by that dopamine increase in frame rate.
link |
If that isn't clear, just know this.
link |
When you're in the ice bath, your dopamine levels are high.
link |
When your dopamine levels are high,
link |
your experience of the discomfort of that ice bath
link |
is at higher resolution.
link |
Now, up until now, I've been talking about how dopamine
link |
and to some extent serotonin can differentially impact
link |
your perception of how fast or how slowly things
link |
are happening in the moment.
link |
But remember, we have prospective time,
link |
we have our experience of time in the moment,
link |
and we have retrospective time.
link |
And there are beautiful studies that have showed
link |
that the dopaminergic state changes the way,
link |
not just that we experience things now,
link |
but that it changes the way in which we remember things
link |
in the past and the rate at which those things occurred,
link |
and those are in opposite direction.
link |
So to make this very simple,
link |
if something that you experience is fun or varied,
link |
meaning it has a lot of different components in it,
link |
and is, in other words, is associated with an increase
link |
in dopamine in your brain,
link |
you will experience that as going by very fast.
link |
Now, this is different than the ice bath,
link |
which I just said you experience as going by very slowly,
link |
but here I'm talking about something that's fun and varied
link |
that you really like,
link |
and you'll feel like it goes by very, very fast.
link |
Imagine an amazing day for a kid in an amusement park.
link |
They can do a ton of things, it's all new,
link |
they're very excited,
link |
and they'll feel like it goes by very fast.
link |
But later, they will remember that experience
link |
as being very long,
link |
that it was a long day full of many, many events.
link |
And so there's this paradoxical relationship
link |
between how we perceive fun, exciting, varied events
link |
in the present and how we remember them in the past.
link |
For those of you who have gone on vacation,
link |
if you've had an amazing day on vacation,
link |
it'll seem like, or an amazing vacation overall,
link |
it will seem like it goes by very fast.
link |
The last day of vacation, you sort of go,
link |
whoa, it went by so fast because there's so much happening.
link |
But in memory, six to eight months later,
link |
you'll remember, wow, that just went,
link |
that was a long, long thing.
link |
We had this, then we had that, then we did this,
link |
It tends to spool out in a longer memory
link |
than the actual experience.
link |
Conversely, if you are bored with something
link |
or it's something you really don't like,
link |
it's going to seem like it takes a long time
link |
to go through that experience in the moment.
link |
But retroactively, looking back,
link |
it will seem like that moment was very short.
link |
So if the other day I was waiting in the waiting room
link |
for the dentist, it was pretty boring.
link |
I was just kind of sitting there.
link |
There wasn't much going on.
link |
And it did seem like it was going on an awfully long time.
link |
But indeed, looking back, it just seems like,
link |
okay, I sat in that room, not much happened.
link |
And so it seems like a very short time been.
link |
This seems to be an efficiency
link |
of how the brain stores information.
link |
Dopamine being associated, of course,
link |
with fun and varied experiences
link |
and low dopamine being associated with kind of empty,
link |
boring or what at the time seemed like long experiences.
link |
And this whole thing has been stamped down
link |
into the scientific literature by those earlier experiments
link |
where they take human beings
link |
and isolate them in certain environments,
link |
take away all the clocks and watches and cues
link |
and about what time of day it is
link |
and what time of night it is
link |
and allow people to have a life
link |
where they can either read and work and do things
link |
or where they have very little to do.
link |
When people are isolated in very boring environments
link |
and they don't have access to time cues, time dilates.
link |
They tend to assume that time has gone on very, very long.
link |
And so the reason I bring this up is
link |
we aren't just driven by the circadian clocks
link |
and the circannual clocks and these ultradian clocks.
link |
We are driven by these timers
link |
that vary depending on our level of excitement.
link |
And they vary depending on our level of excitement
link |
because of these neuromodulators, dopamine and serotonin.
link |
So the way I like to think about it
link |
is that you have two clocks, two stopwatches.
link |
One is a dopaminergic stopwatch
link |
that fine slices really closely.
link |
It's like counts off milliseconds
link |
and it's grabbing a movie of your experience
link |
at very high resolution.
link |
And then the other hand, you have a stopwatch
link |
that's gathering big time bins,
link |
big ticks along the hand is moving at bigger intervals,
link |
And depending on whether or not you're excited
link |
or whether or not you're bored,
link |
you're using different stopwatches on time
link |
and therefore you're perceiving your experience differently.
link |
One very interesting aspect to the way
link |
that neuromodulators like dopamine and novelty
link |
interact with time perception and memory
link |
is how we perceive our relationship to places and people.
link |
So really interesting literature
link |
showing that the more novel experiences we have in a place,
link |
the more we feel we know that place, obviously,
link |
but the longer we feel we've been there.
link |
So here's the kind of gedanken or thought experiment
link |
that illustrates what's in the literature.
link |
Let's say I were to move to New York City.
link |
I happen to really like New York City.
link |
I've never lived there, but let's say I lived there.
link |
I lived in a given apartment for a year
link |
and I would have a number of different experiences
link |
in this mental experiment.
link |
Let's say I had 100 different exciting and new experiences.
link |
I would, at the end of that year,
link |
feel as if I lived there a certain period of time, one year.
link |
I would actually know I lived there one year.
link |
If, however, I lived in three different places
link |
in New York City and I met three times as many people
link |
and I had three times as many novel experiences,
link |
I would actually feel as if I had been there much longer
link |
than had I only lived in one location.
link |
This is also true for social interactions.
link |
When we move to multiple or several novel environments
link |
with somebody else, we tend to feel as if we know
link |
that person much better and that they know us much better.
link |
Now, of course, we get the opportunity to interact
link |
with those people in different contexts.
link |
And so, indeed, we do get the opportunity to see them,
link |
for instance, at the coffee shop, how they order coffee,
link |
you maybe go to a sports event, how they act there,
link |
maybe how they interact with your family.
link |
You're getting a sense of them in different contexts.
link |
That's certainly playing a role,
link |
but it seems as if the more novelty you experience
link |
with somebody, not only the more familiar they are to you,
link |
but the more time you feel you've spent with them,
link |
even though the total amount of time
link |
can be exactly the same.
link |
And so that's a very interesting aspect
link |
of how our perception of time and these neuromodulators
link |
and novelty can shape the way,
link |
not just that we perceive a given event in our world,
link |
but how we relate to a place or relate to a person.
link |
So we've talked a lot about the different neurochemicals
link |
and how those neurochemicals can influence
link |
our perception of time.
link |
We haven't talked a lot about the neural circuits
link |
and the various areas of the brain that underlie this.
link |
I do want to touch on that
link |
by highlighting a really wonderful study.
link |
This was a study published in Neuron,
link |
also a cell press journal, excellent journal.
link |
The title of the paper is Behavioral, Physiological,
link |
and Neural Signatures of Surprise
link |
During Naturalistic Sports Viewing.
link |
This experiment is really cool.
link |
They did brain imaging on individuals
link |
who are watching basketball games.
link |
These were basketball games that actually took place,
link |
that were recorded.
link |
And the subjects watching these basketball games,
link |
in some cases, not all,
link |
had some interest in who would win or lose.
link |
And in some cases, not all,
link |
the subjects in these studies had some prior knowledge
link |
of which team they thought was better,
link |
which team was likely to win or not likely to win.
link |
The basic findings of the study were that
link |
they could measure surprise
link |
by the release of dopamine in two areas of the brain,
link |
part of what are called, is called, excuse me,
link |
the mesolimbic reward pathway.
link |
So the two areas of the brain that are important here
link |
are the nucleus accumbens and the VTA,
link |
the ventral tegmental area.
link |
These are areas that release dopamine
link |
as kind of a token of reward
link |
anytime something is surprising
link |
or a positive expectation is met, okay?
link |
So if I predict that my team dribbling down court
link |
is going to score on this drive
link |
and they get the ball in the basket,
link |
a little bit of dopamine is released,
link |
these two brain areas light up in the functional imaging,
link |
so-called FMRI, functional magnetic resonance imaging
link |
that they used in the study.
link |
What's really interesting about this study
link |
is not just that dopamine was released
link |
anytime that something the subject wanted to see happened,
link |
anytime they wanted to see their team score, they scored,
link |
but also during surprise.
link |
So if they thought, for instance,
link |
and they would hit a button to predict
link |
that their team was going to score on this particular drive
link |
and they didn't, well, then dopamine could also be released
link |
in response to that surprise.
link |
So this speaks again to dopamine
link |
being something that's important,
link |
not just for positive events, but for unexpected events.
link |
Now that's all very interesting
link |
and speaks to the fact that dopamine
link |
is a kind of flexible currency in the brain.
link |
It's doled out, if you will, or released
link |
when something that one hopes will happen happens,
link |
and it's released when there's a surprise,
link |
even if it's kind of a negative surprise,
link |
it's not something that the subject wanted to happen.
link |
But the more interesting thing
link |
is how that relates to time perception.
link |
What they found was,
link |
regardless of what caused the dopamine release,
link |
the frequency of dopamine release
link |
predicted how the subjects parsed the time bins
link |
of the game they were watching.
link |
What do I mean by that?
link |
Well, when you watch a basketball game
link |
or you watch anything, children playing
link |
or talking to your spouse or whatever,
link |
you're batching time.
link |
How are you batching time?
link |
Well, you could batch a meal by the, I don't know,
link |
the appetizer, the main course, and the dessert,
link |
but it turns out that's not what you're doing.
link |
You're batching time
link |
according to the frequency of dopamine pulses,
link |
the frequency of dopamine release.
link |
And that's what they saw in this study.
link |
If they evaluated people's perceptions
link |
of the passage of time,
link |
what they found is that that matched,
link |
not whether or not it was a particular time point
link |
not whether or not their team was going down court
link |
or running back up court to play defense,
link |
but the dopamine release served as markers,
link |
which would predict the frame rate
link |
of their perception of the experience.
link |
And if that sounds complicated,
link |
what I mean is how often and when you release dopamine
link |
is actually setting the frame rate
link |
on the entire perception of everything,
link |
not just for positive events or negative events.
link |
So what this means is as you were going through life,
link |
dopamine and the release of dopamine is saying that's over
link |
and now you're in a new phase of your life,
link |
even if it's very short, right?
link |
So if I get up in the morning and I'm like,
link |
oh, I really need a cup of coffee,
link |
as you probably all know,
link |
I wait 90 minutes to 120 minutes before I drink my coffee,
link |
but then I get my coffee
link |
and surely there's a dopamine hit there, I promise you.
link |
I actually am starting to carve up my day
link |
according to dopamine hits.
link |
I am with consciously or subconsciously,
link |
I'm actually carving up my experience
link |
according to when I'm getting dopamine throughout my day.
link |
This governance over our perception of time
link |
that dopamine has points to a very clear,
link |
very actionable and very powerful tool.
link |
And that is a tool that many people have talked about before
link |
People have discussed habits in a variety of contexts,
link |
but in the context of dopamine reward and time perception,
link |
what this means is that placing specific habitual routines
link |
at particular intervals throughout your day
link |
is a very, not just convenient,
link |
but a very good way to incorporate the dopamine system
link |
so that you divide your day into a series
link |
of what I would call functional units.
link |
What would this look like?
link |
It would mean waking up and having one specific habit
link |
that you always engage in that causes a release of dopamine.
link |
You could say, well, great, that'll make me feel good.
link |
And I would agree,
link |
dopamine release generally makes us feel motivated,
link |
but it would have an additional effect
link |
of marking that time of day
link |
as the beginning of a particular time bin.
link |
Then inserting another habit,
link |
perhaps the beginning of, I don't know,
link |
your breakfast or something,
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but recognizing that that's a habit
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and being fairly habitual.
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You don't have to be obsessively precise about the timing,
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but that regular sequencing of things
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is going to lead not just to dopamine release
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as it relates to reward and motivation and feeling good,
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but it actually becomes the way
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in which we carve up our entire experience of our day.
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And this is almost a circular argument.
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You could say, well, of course, I do one thing,
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then I do the next, then I do the next,
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and that's how I perceive my day.
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That's my day, it's my list, it's my to-do list, et cetera.
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But what I'm saying is that on the basis of this study,
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I should mention the first author,
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his last name is Antony, it was Antony et al.
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It was published in 2020, the study on basketball viewing.
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What it points to is that by engaging in specific habits
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that we know we can perform well,
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we are actually setting the frame rate on our day.
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And so I think there will soon come a time
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where human beings are not just thinking of,
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okay, my morning routine and my afternoon routine,
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I think that can be useful, and in fact,
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I used or mentioned a structure of that sort
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earlier in their episode,
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but rather thinking about what's actually going on
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at the level of our biology,
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which is that dopamine is marking time.
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Habits are a very clear way
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in which we can invoke dopamine release
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and therefore provide time markers.
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And what this means is that, for instance,
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during your morning, you might insert habit one
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and habit two at say, I don't know, 8 a.m. and 10 a.m.,
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and in doing that, that marks an epoch,
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a little batch of time in your morning routine
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that's distinct from the second half of your morning.
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In other words, habits serve as flankers or markers
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for the passage of your day.
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Now, if that seems kind of hyper neurotic
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or why would I want to structure my life like that,
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I would say that many people would do well
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to structure their life like that and to utilize habits,
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not just for sake of what you do during the habit,
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but because of the fact that the habits serve as a marker
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because of the way they can evoke dopamine release.
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And in doing that, you're able to segment your day
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into a bunch of smaller, if you want them to be smaller,
link |
or larger functional units.
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If anyone wants to experiment with this,
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the Huberman Lab podcast puts out a newsletter.
link |
It's called the Neural Network Newsletter.
link |
You can sign up for it at hubermanlab.com.
link |
We put it out each month.
link |
You can see the previous newsletters.
link |
They're zero cost.
link |
We have our privacy statement there.
link |
We don't share your email or anything.
link |
And there you'll find the 12 Steps to Improving Sleep
link |
was the first one.
link |
There's another, the second newsletter
link |
was all about neuroplasticity
link |
and using scientific literature
link |
to improve learning and teaching.
link |
And in the next newsletter,
link |
I intend to include a example protocol
link |
of how one could use habits
link |
and the relationship between habits and dopamine,
link |
dopamine and time perception to structure your day
link |
according to performance of particular types of tasks.
link |
Today, we covered a lot about time perception.
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We certainly didn't cover everything about time perception,
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but we covered things like entrainment,
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the role of dopamine, habits, and various routines
link |
that can adjust your sense of time
link |
for sake of particular goals.
link |
If you're interested in learning more about time perception,
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I'd like to point you to a really excellent book
link |
called Your Brain is a Time Machine,
link |
the Neuroscience and Physics of Time.
link |
The book was written by Professor Dr. Dean Buonamano,
link |
who's a professor at UCLA
link |
and a world expert in the neuroscience and physics of time.
link |
I do hope to get Dean on the podcast
link |
in the not too distant future.
link |
If you're learning from and or enjoying this podcast,
link |
please subscribe to our podcast channel on YouTube.
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It's simply Huberman Lab on YouTube.
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And there you can also leave us suggestions
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for future guests and topics
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and questions about the podcast episodes
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in the comment section on YouTube.
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In addition, please subscribe to our podcast
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on Apple and or Spotify.
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And on Apple, you have the opportunity
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to leave us up to a five-star review.
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You can also follow us on Instagram.
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On Instagram, I do short neuroscience tutorials
link |
and tools and protocols.
link |
I cover recent papers,
link |
many of which are not included on the podcast.
link |
We also have a Patreon.
link |
It's patreon.com slash Andrew Huberman,
link |
and there you can support the podcast
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at any level that you like.
link |
Not so much today, but on many previous episodes
link |
of the Huberman Lab podcast, we discuss supplements.
link |
And while supplements aren't necessary for everybody,
link |
many people derive great benefit from supplements
link |
for sleep, for focus, and so forth.
link |
One issue with supplements, however,
link |
is that what's listed on the bottle of various supplements
link |
isn't always what's included in the bottle.
link |
And the quality of ingredients varies tremendously
link |
across different supplement manufacturers.
link |
For that reason, we've partnered with Thorne,
link |
that's T-H-O-R-N-E,
link |
because Thorne supplements have the highest levels
link |
of stringency of any supplement company out there
link |
that we are aware of.
link |
They work with all the major sports teams.
link |
They work with the Mayo Clinic.
link |
And so we're delighted that we partnered with them.
link |
If you'd like to see the supplements that I take,
link |
you can go to Thorne,
link |
that's T-H-O-R-N-E dot com slash the letter U slash Huberman
link |
to see the supplements that I take,
link |
and you can get 20% off any of those supplements.
link |
If you enter the Thorne site through that portal,
link |
you can also get 20% off any of the supplements
link |
that Thorne makes.
link |
Thank you for your time and attention today.
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And last, but certainly not least,
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thank you for your interest in science.
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I'll see you next time.