back to indexUsing Science to Optimize Sleep, Learning & Metabolism | Huberman Lab Podcast #3
link |
Welcome to the Huberman Lab Podcast,
link |
where we discuss science and science-based tools
link |
for everyday life.
link |
I'm Andrew Huberman,
link |
and I'm a professor of neurobiology and ophthalmology
link |
at Stanford School of Medicine.
link |
This podcast is separate from my teaching
link |
and research roles at Stanford.
link |
It is, however, part of my desire and effort
link |
to bring zero cost to consumer information
link |
about science and science-related tools
link |
to the general public.
link |
Along those lines, I want to thank the sponsors
link |
of today's podcast.
link |
Our first sponsor is Athletic Greens,
link |
which is an all-in-one vitamin mineral
link |
probiotic liquid supplement.
link |
I've been using Athletic Greens since 2012,
link |
because I really like getting
link |
my total vitamin mineral base covered
link |
in one easy-to-consume product.
link |
It also tastes really good.
link |
I've mixed mine with a little bit of lemon juice.
link |
I've been doing that well for well over a decade now.
link |
And the inclusion of probiotics is important to me
link |
because there's a lot of data out there right now
link |
about the importance of gut health
link |
for the immune system, for mood.
link |
And so by combining all these things in one product,
link |
I get all those things at once.
link |
If you want to try Athletic Greens,
link |
you can go to athleticgreens.com slash Huberman,
link |
and that will give you a special offer
link |
where you will get a year's supply
link |
of liquid vitamin D3 and K2.
link |
Vitamin D3 has been shown to be important
link |
for various aspects of immune function,
link |
as well as other biological functions.
link |
And so once more, if you want to try Athletic Greens
link |
and get the year's supply of vitamin D3, K2,
link |
just go to athleticgreens.com slash Huberman.
link |
The other sponsor of today's podcast is Inside Tracker.
link |
Inside Tracker is a way to measure metabolic factors,
link |
hormones, and DNA-related factors
link |
by way of blood tests and saliva
link |
in order to assess one's health.
link |
I'm a big believer in blood tests and saliva tests
link |
for assessing one's health markers because I like data.
link |
And there's really no other way to measure
link |
what's going on in one's body
link |
without taking the occasional blood test or saliva test.
link |
You can guess what's going on,
link |
but if you really want to know what's going on
link |
under the hood, Inside Tracker can be of great help.
link |
One of the problems with a lot of products out there,
link |
or just regular blood testing,
link |
is that you get a lot of data back
link |
about the levels of various hormones, metabolic factors,
link |
et cetera, but you don't know what to do with those data.
link |
Great thing about Inside Tracker is it is provided
link |
in a format, they have an online dashboard,
link |
that given your particular levels of various things,
link |
directs you toward potential lifestyle-related changes
link |
like changes in exercise or changes in sleep patterns
link |
or changes in nutritional patterns
link |
that can really help move those markers and those numbers
link |
on those metabolic factors, hormones, et cetera,
link |
in the direction that you want.
link |
If you'd like to try Inside Tracker,
link |
you can go to insidetracker.com slash Huberman.
link |
And if you do that,
link |
you'll get 25% off their program at checkout.
link |
Okay, let's get started.
link |
Today is episode three of the podcast
link |
and it is Office Hours.
link |
Office Hours, as many of you know,
link |
is where students come to the office of the professor,
link |
sit down and ask questions,
link |
requesting clarification about things that were confusing
link |
or to simply go down the route of exploring a topic
link |
with more depth and detail.
link |
I asked for your questions to be listed
link |
in the comment section of the previous two episodes
link |
of the podcast on YouTube, as well as on Instagram.
link |
And I, first of all, just want to thank you
link |
for the many questions, they are excellent.
link |
We distilled from that large batch of questions
link |
to two types of questions,
link |
questions that were asked very often
link |
and were liked very often with a little thumbs up like tab,
link |
as well as questions that we thought could really expand
link |
on the topics that we've covered previously.
link |
And today we're going to cover both of those.
link |
If we did not get to your question, please don't despair.
link |
We will keep track of those.
link |
And we have several more episodes devoted to this topic
link |
of sleep and wakefulness and learning
link |
during the month of January, maybe even, you know,
link |
leaking over a little bit into the month of February.
link |
So we have time, that's one of the unique formats
link |
of this podcast is that we have time for dialogue.
link |
We have time for your questions
link |
and we have time to really go deep into these topics.
link |
It's official, Costello is sleeping in the background.
link |
So if you hear snoring, Costello is going to be keeping time
link |
with his deep and melodic snoring.
link |
So the questions that we received,
link |
I batched crudely into a couple of different categories,
link |
light, exercise, supplementation,
link |
temperature, learning, plasticity,
link |
and mood and sort of mood related disorders.
link |
There were a lot of questions about those.
link |
Before we begin any of this,
link |
I want to point out something that I always say,
link |
it sounds like boilerplate,
link |
but it's important not just to protect me,
link |
but to protect you, which is that I am not a physician.
link |
I'm not a medical doctor.
link |
I don't prescribe anything, including behavioral protocols.
link |
I'm a professor, so I profess a lot of things
link |
based on quality peer-reviewed studies.
link |
You should take that information,
link |
you should filter it through whatever it is
link |
that you currently happen to be dealing with,
link |
whether or not that's health or illness,
link |
you should consult with a licensed healthcare professional
link |
before you add or remove anything
link |
from your daily life protocol.
link |
I'm not responsible for your health, you are,
link |
so be smart with this information
link |
and be a stringent filter, as we say.
link |
Let's get started on the actual material.
link |
Somebody asked, what is the role of moonlight and fire?
link |
I'm presuming they mean fireplace or candle
link |
or things of that sort.
link |
In setting circadian rhythms,
link |
is it okay to view moonlight at night
link |
or will that wake me up?
link |
Will a fire in my fireplace or using candlelight
link |
be too much light?
link |
Also offers me the opportunity to share with you
link |
what I think is a quite beautiful definition
link |
of what light is in a quantitative sense.
link |
So I've mentioned a few times the use of apps
link |
and light meters and things to measure things like lux,
link |
which sometimes are also described in terms of candelas.
link |
So those are the two units for measuring light intensity.
link |
Typically lux, L-U-X, is the unit.
link |
And so before we go forward and discuss this many lux
link |
or that many lux, I want to just tell you what a lux is
link |
because it relates to this question.
link |
One lux equals the illumination of one square meter surface
link |
at one meter away from a single candle.
link |
So somebody actually decided at some point
link |
that the amount of illumination at one square meter surface
link |
one meter away from a single candle, that equals one lux.
link |
So when we talk about 6,000 lux of light intensity
link |
or 10,000 lux of light intensity,
link |
now you have a kind of a reference or a framework
link |
that would be the equivalent of,
link |
you could think of it as 6,000 candles
link |
all with their light intensity shown on one square meter
link |
from one meter's distance away.
link |
Or of course, if it was a different number of lux
link |
it would be a different number of candles.
link |
So you get the idea.
link |
Here's the great thing.
link |
Turns out that moonlight, candlelight
link |
and even a fireplace,
link |
if you have one of these roaring fires
link |
going in the fireplace,
link |
do not reset your circadian clock at night
link |
and trick your brain into thinking that it's morning.
link |
Even though if you've ever sat close to a fireplace
link |
or even a candle, that light seems very bright.
link |
And there are two reasons for that that are very important.
link |
The first one is that these neurons in your eye
link |
that I discussed in the previous episode,
link |
these melanopsin ganglion cells,
link |
also called intrinsically photosensitive ganglion cells,
link |
those cells adjust their sensitivity across the day.
link |
And those cells respond best to the blue-yellow contrast
link |
present in the rising and setting sun,
link |
so-called low solar angle sun,
link |
also discussed in the previous episode.
link |
But those cells adjust their sensitivity
link |
such that they will not activate the triggers in the brain
link |
that convey daytime signals when they view moonlight,
link |
even a full moon, a really bright moon or fire.
link |
Now, this does raise an interesting kind of thought point,
link |
which is a lot of people have talked about lunacy
link |
and the fact that when there's a full moon out,
link |
people act differently and behave differently.
link |
There's a lot of lore around that.
link |
There's actually a little bit of quality science around that
link |
that maybe we can address in the future.
link |
But moonlight is typically not going to wake us up too much,
link |
except maybe if the moon is really full and really bright,
link |
there's possibility for that.
link |
So provided you're not going to burn down
link |
the structure you're in,
link |
you're not going to burn down the forest,
link |
enjoy your fireplaces, enjoy your lights from candles,
link |
and those are perfectly safe
link |
without disrupting your circadian rhythm.
link |
Because we talked about just how crucial it is
link |
to avoid bright lights
link |
between the hours of about 10 p.m. and 4 a.m.,
link |
except when you need to view things for sake of safety
link |
or work and so forth.
link |
I also received a lot of questions about red light.
link |
Now, I think I was asked those questions
link |
because red light is used
link |
in a number of different commercial products
link |
where these products tend to include
link |
a sheet of very bright red lights
link |
that one is supposed to view early in the day.
link |
And there are various claims
link |
attached to these red light devices,
link |
that they improve mitochondrial function,
link |
that they improve metabolism.
link |
I'm going to be really honest,
link |
and I can't name brands,
link |
and I'm not going to name particular studies
link |
because what I'm about to say about these studies
link |
is not particularly unkind,
link |
but let's just say that none of the studies that I've seen,
link |
except for one that I'll talk about in a moment,
link |
pointing to the positive effects of red light
link |
on the visual system,
link |
are published in blue ribbon journals.
link |
They tend to be published in journals
link |
that I had to work hard to find.
link |
I'm not sure what the peer review and stringency level is.
link |
Now, that's not to say red light isn't beneficial
link |
because there is one study in particular
link |
that came from Glenn Jeffrey's lab
link |
at the University of College London.
link |
It was published last year.
link |
Glenn is somebody I happen to know,
link |
has an excellent reputation, excellent vision scientist.
link |
What this study essentially showed,
link |
and again, this is a study that I very much like the data
link |
and think it was done with very high standards.
link |
What this study shows is that viewing red light
link |
for a few minutes each morning can have positive effects
link |
on mitochondria in a particular retinal cell type
link |
that tends to degenerate or decline in function
link |
with age in humans,
link |
and that cell type is the photoreceptor.
link |
The photoreceptor is a type of cell in your eye
link |
that sits at the back of the eye.
link |
It's kind of some distance away from the ganglion cells,
link |
and it's the cell that converts light information
link |
into electrical signals that the rest of the retina
link |
and brain can understand.
link |
These are vitally important cells.
link |
Without them, people are blind.
link |
And many people's vision gets worse with age,
link |
in particular age-related macular degeneration,
link |
but also related to some other factors,
link |
including photoreceptor functionality
link |
just getting worse with time.
link |
And what Glenn showed was that red light flashes
link |
delivered in particular early in the day
link |
but not late in the day can help repair the mitochondria.
link |
Now, this study needs more support from additional studies,
link |
They are doing a clinical trial.
link |
They did report on what I think it was 12 patients.
link |
And so the work is ongoing, but that was very interesting.
link |
And it points to some potentially really useful things
link |
However, most of the questions I got about red light
link |
for sake of office hours
link |
were about the use of red light later in the day.
link |
So here's the deal.
link |
In principle, red light
link |
will not stimulate the melanopsin retinal neurons
link |
that wake up the brain and circadian clock
link |
and signal daytime.
link |
However, most of the red lights,
link |
in particular the red lights
link |
that come on these sheets of these products
link |
that people are supposed to view them
link |
in order to access a number of proclaimed health effects,
link |
those are way too bright
link |
and would definitely wake up your body and brain.
link |
So if you're going to use those products,
link |
and I'm not suggesting you do or you don't,
link |
but if that's your thing,
link |
you would want to use those early in the day.
link |
Who knows, you might even derive some benefit
link |
on mitochondrial function in these photoreceptors.
link |
But if you're thinking about red light
link |
for sake of avoiding the negative effects of light
link |
later in the day and at night,
link |
then you want that red light to be very, very dim,
link |
certainly much dimmer
link |
than is on most of those commercial products.
link |
Now, do you need red lights?
link |
No, although red lights are rather convenient
link |
because you can see pretty well with them on,
link |
but if they're dim, they won't wake up the circadian clock,
link |
they won't have this dopamine disrupting thing
link |
that we talked about in the previous podcast.
link |
So there's a role for red light
link |
potentially early in the day
link |
and for mitochondrial repair in the photoreceptors,
link |
there's a role for dim red light
link |
later in the day and at night.
link |
So you're starting to notice a theme here,
link |
which is that there's no immediate prescription
link |
of look at these lights,
link |
it's look at these lights potentially,
link |
if that's what you want to do at particular times of day
link |
and with particular intensities.
link |
It brings us back to the blue light issue,
link |
which is so many people are obsessed
link |
with avoiding blue light,
link |
but you actually want a ton of blue light
link |
early in the day and throughout the day,
link |
so don't wear your blue blockers then,
link |
or maybe even don't wear them at all.
link |
And at night, it doesn't matter
link |
if you have blue blockers on,
link |
if the lights are bright enough,
link |
then you're still going to be activating
link |
these cells and mechanisms.
link |
I just want to add something
link |
about the science behind the blue blocker confusion.
link |
So these melanopsin retinal cells do react to blue light.
link |
That is the best stimulus for one of these melanopsin cells,
link |
which led to the belief that blue blockers
link |
would be a good thing for preventing
link |
resetting of the circadian clock at night
link |
and deleterious effects of screens, et cetera.
link |
However, the people that made these products
link |
failed to actually read the papers start to finish,
link |
or if they did, they didn't comprehend a critical element,
link |
which is that most of those papers early on
link |
took those neurons out and put them in a dish,
link |
and when they did that, they divorced those neurons
link |
from their natural connections in the eye.
link |
Turns out in your eye, in my eye right now,
link |
because that's what we care about, these cells exist,
link |
and these cells respond to blue light,
link |
but also to other wavelengths of light
link |
because they not only respond directly to light
link |
as they do in a dish,
link |
they also respond to input from photoreceptors.
link |
So if you talk to anyone in the circadian biology field,
link |
they'll tell you, oh, yeah, this blue light thing
link |
has really gotten out of control
link |
because people assume that blue light is the culprit
link |
because blue light is the best stimulus.
link |
That doesn't mean that blue light is the only stimulus
link |
that will trigger these cells, okay?
link |
So like many things, a scientific paper can be accurate
link |
without being exhaustive, and a lot of claims about products
link |
can be accurate but not exhaustive.
link |
So blue light during the day is great.
link |
Get that screen light, get that sunlight especially,
link |
get overhead lights.
link |
I talk about all this in the previous podcast,
link |
but at night, you really want to avoid those bright lights,
link |
and it doesn't matter if it's blue light or something else,
link |
and so there was a real confusion about the papers
link |
and the data when most of those product recommendations
link |
Okay, while we're on that topic,
link |
let's talk about light in other orifices of the body.
link |
I made kind of a joke about this the last podcast episode,
link |
but a couple of people wrote to me and said,
link |
well, I've seen some claims that light delivered
link |
to the ears, into the ears or the roof of the mouth
link |
or up the nose can be beneficial
link |
for setting circadian rhythms.
link |
No, not directly anyway,
link |
and this is a great opportunity for us to distinguish
link |
between what is commonly called the placebo effect,
link |
but a more important way to think about any manipulation,
link |
behavioral or otherwise, that you might do
link |
is the difference between modulation and mediation.
link |
There are a lot of things that will modulate your biology.
link |
Putting a couple of lights up your nose,
link |
please don't do this, might modulate your biology
link |
by way of the stress hormone that's released
link |
when you stuff those things up your nose.
link |
Remember earlier, previous podcasts,
link |
I said that virtually anything will phase shift
link |
your circadian rhythm if it's different
link |
and dramatic enough.
link |
So the question is, is it the light delivered up the nose
link |
or through the ears or some other orifice
link |
that's mediating the process?
link |
Is it actually tapping into the natural biology
link |
of the system that you're trying to manipulate?
link |
And this is where I like to distinguish
link |
between real biology and hacks.
link |
I don't like the word hack
link |
or frankly neuro-hacking or bio-hacking.
link |
I just don't like the term
link |
because a hack is using something for a purpose
link |
for which it was not intended, right?
link |
But where you can kind of, it's a kind of a cheat
link |
and that's not how biology works well.
link |
So I try and distinguish between things
link |
that really mediate biological processes
link |
and things that modulate them.
link |
There are a number of commercial products out there
link |
with some studies attached to them
link |
claiming that light delivered to the ears
link |
or wherever can adjust your wakefulness
link |
or adjust your sleep.
link |
I've looked at those papers again,
link |
I'm probably going to lose some friends by saying this
link |
but maybe I'll gain a few as well.
link |
Not blue ribbon journals frankly,
link |
oftentimes read the small print.
link |
There was a conflict of interest clause there
link |
related to commercial interests.
link |
If somebody disagrees with me outright on this
link |
and can send to me a peer reviewed paper
link |
published in a quality journal about light delivered
link |
anywhere but the eyes of humans
link |
that can mediate circadian rhythms, wakefulness, et cetera.
link |
I'm more than happy to take a look at that
link |
and change my words and stance on this
link |
and do it publicly of course.
link |
But until then, I'm guessing that the proper controls
link |
were not done of adjusting for heat that could be delivered
link |
which can definitely shift circadian rhythms.
link |
We're going to talk about temperature
link |
and other things like that.
link |
So light to the eyes folks is where these light effects
link |
work in humans, in other animals
link |
they have extraocular photoreception in humans, no.
link |
And just be mindful.
link |
I mean, I'm not trying to encourage people
link |
to avoid certain products in particular
link |
but just be mindful of this difference
link |
between modulation and mediation.
link |
And mediating a process through a hardwired
link |
or longstanding biological mechanism
link |
is really where you're going to see
link |
the powerful effects over time.
link |
I also, as you've probably noticed,
link |
I really tend to favor behavioral tools
link |
and zero cost tools first and getting those dialed in
link |
before you start plugging in and swallowing
link |
and putting things in various places
link |
just to really figure out how your biology works
link |
Unless there's of course a clinical need
link |
to take a prescribed drug in which case
link |
by all means, listen to your doctor.
link |
Okay, a huge number of people asked me about
link |
what about light through windows?
link |
And I actually did an Instagram post about this.
link |
Look, setting your circadian clock
link |
with sunlight coming through a window
link |
is going to take 50 to 100 times longer.
link |
If you want the date on that,
link |
I'd be happy to send you to the various papers
link |
that were described in the previous podcast
link |
that Jamie Zeitzer from Stanford
link |
and I have discussed also elsewhere.
link |
But here's really the key thing with this.
link |
Do the experiment.
link |
You can download the free app Light Meter.
link |
You can have a bright day outside or some sunlight.
link |
Hold up that app, take a picture.
link |
It'll tell you how many lux.
link |
Now you know what lux are.
link |
It will tell you how many lux are in that environment.
link |
Now close the window.
link |
And if you want, close the screen or don't open the screen.
link |
You can do all sorts of experiments
link |
and you'll see that it will at least half
link |
the amount of lux and it doesn't scale linearly.
link |
Meaning let's say I get a 10,000 lux outside,
link |
5,000 looking out through an open window
link |
and then I close the window and it's 2,500 lux.
link |
It does not mean that you just need to view that sunlight
link |
for twice as long if it's half as many lux, okay?
link |
It's not like 2,500 lux means you need to look
link |
for 10 minutes and 5,000 lux means you look for five minutes.
link |
It doesn't scale that way
link |
just because the biology doesn't work that way.
link |
Best thing to do is to get outside if you can.
link |
If you can't, next best thing to do
link |
is to keep that window open.
link |
It is perfectly fine to wear prescription lenses
link |
Why is it okay to wear prescription lenses and contacts
link |
when those are glass also?
link |
But looking through a window diminishes the effect?
link |
Well, we should think about this.
link |
The lenses that you wear in front of your eyes
link |
by prescription or on your eyes are designed
link |
to focus the light onto your neural retina.
link |
In fact, that's what nearsightedness is,
link |
is when the image,
link |
because your lens doesn't work quite right,
link |
the image falls in front of the neural retina,
link |
wearing a particular lens in front of that
link |
focuses the lens onto your retina, onto these very neurons
link |
so they can communicate that to the brain.
link |
Costello is loving this.
link |
He's deep in sleep.
link |
And if we, maybe we could play him some tones
link |
and he'll remember it later based on the studies
link |
we're going to talk about in a little bit.
link |
I don't know how we'd know if he remembered it or not,
link |
but prescription lenses are fine.
link |
In fact, they're great for this reason.
link |
They're actually focusing the light onto the retina.
link |
So think about this logically
link |
and all of a sudden it makes perfect sense.
link |
Your glass window or your windshield
link |
or the side window of your car,
link |
it isn't optically perfect to bring the image
link |
and the light onto your retina.
link |
In fact, what it's doing is it's scattering
link |
and filtering light,
link |
in particular the wavelengths of light that you want.
link |
So if you live in a low light environment,
link |
lots of questions about this.
link |
We talked about this the previous podcast,
link |
but just get outside for longer.
link |
Or, and or use really bright lights inside.
link |
Okay, so let's think about why
link |
I'm making some of these recommendations
link |
because I think it can really empower you
link |
with the ability to change your behavior
link |
in terms of light viewing and other things,
link |
depending on time of year,
link |
depending on other lifestyle factors.
link |
The important point to understand is that early in the day,
link |
your central circadian clocks and all these mechanisms
link |
are looking for a lot of light.
link |
I mean, they don't have a mind of their own,
link |
but it needs a lot of light
link |
to trigger this daytime signal alertness, et cetera.
link |
And early in the day, but not in the middle of the day,
link |
you can sum or add photons.
link |
So there's this brief period of time early in the day
link |
when the sun is low in the sky,
link |
when your brain and body are expecting
link |
a morning wake up signal,
link |
where let's say it's not that bright outside.
link |
Someone sent me a picture or a little movie
link |
of their walk in England and it was pretty overcast.
link |
And they were using light meter and they said,
link |
it's only about 700 lux or maybe even less.
link |
And I said, well, stay outside longer.
link |
But when you get inside,
link |
turn on the lights really bright
link |
and overhead lights in particular,
link |
because those will be best for stimulating these mechanisms.
link |
And that's because at least
link |
for the first few hours of the day,
link |
you can continue to sum or add photon activation
link |
of the cells in the eye and the brain.
link |
In the middle of the day, once the sun is overhead,
link |
or even if you stay inside all morning,
link |
and then you're in the circadian dead zone,
link |
which sounds terrible.
link |
And it is terrible because it doesn't matter
link |
if you get a ton of artificial light or even sunlight,
link |
you're not going to shift your circadian clock.
link |
You're not going to get that wake up signal.
link |
And then in the evening,
link |
you want to think about this whole system
link |
as being vulnerable to even a few photons of light
link |
because your sensitivity to light really goes up at night.
link |
And I talked last time about how you can protect
link |
against that sensitivity by looking at the setting sun
link |
and watching the evening sun,
link |
even if it's not crossing the horizon
link |
around the time of sunset.
link |
And that's because it adjusts your retinal sensitivity
link |
and your melatonin pathway
link |
so that light is not as detrimental to melatonin at night.
link |
Think about the afternoon sunlight viewing
link |
I think of it as kind of a Netflix inoculation.
link |
It allows me to watch a little bit of Netflix
link |
although it's very hard to watch
link |
a little bit of anything on Netflix.
link |
It seems like there's some other neurobiological process
link |
where I have to watch episode after episode
link |
you can protect yourself against some of that
link |
bad effect of light at night
link |
by looking at light in the evening.
link |
It really does adjust down the sensitivity of the system.
link |
Okay, I want to talk about seasonal changes
link |
in all these things as they relate to mood and metabolism.
link |
So depending on where you are in the world,
link |
Northern hemisphere, Southern hemisphere,
link |
at the equator or closer to the poles,
link |
the days and nights are going to be different lengths.
link |
That just makes sense.
link |
But that translates to real biological signals
link |
that impact everything from wakefulness and sleep times,
link |
but also mood and metabolism.
link |
So here's how this works.
link |
Now, after seeing the previous episode of the podcast
link |
and paying attention here,
link |
you are armed with the knowledge
link |
to really understand how it is that,
link |
believe it or not,
link |
every cell in your body is tuned
link |
to the movement of the planet relative to the sun.
link |
So as all of you know,
link |
the earth spins once every 24 hours on its axis.
link |
So part of that day we're bathed in sunlight,
link |
depending on where we are,
link |
the other half of the day or part of the day,
link |
we're in darkness.
link |
The earth also travels around the sun.
link |
365 days is the time that it takes, one year,
link |
to travel around that sun.
link |
The earth is tilted.
link |
It's not perfectly upright.
link |
So the earth is tilted on its axis.
link |
So depending on where we are in that 365 day journey,
link |
and depending on where we are in terms of hemisphere,
link |
Northern hemisphere, Southern hemisphere,
link |
some days of the year are longer than others.
link |
Some are very short, some are very long.
link |
If you're at the equator,
link |
you experience less variation in day length
link |
and therefore night length.
link |
And if you're closer to the poles,
link |
you're going to experience some very long days.
link |
And you're also going to experience some very short days,
link |
depending on which pole you're at and what time of year
link |
The simple way to put this is depending on time of year,
link |
the days are either getting shorter or getting longer.
link |
Now, every cell in your body adjusts its biology
link |
according to day length,
link |
except your brain, body and cells
link |
don't actually know anything about day length.
link |
It only knows night length.
link |
And here's how it works.
link |
Light inhibits melatonin powerfully.
link |
If days are long and getting longer,
link |
that means melatonin is reduced.
link |
The total amount of melatonin is less
link |
because light is more, therefore melatonin is less.
link |
If days are getting shorter,
link |
light can't inhibit melatonin as much
link |
through the summing of photon mechanisms
link |
that we talked about before.
link |
And that melatonin signal is getting longer.
link |
So every cell in your body actually knows external day length
link |
and therefore time of year
link |
by way of the duration of the melatonin signal.
link |
And in general, it's fair to say that in diurnal animals,
link |
meaning animals like us that tend to be awake
link |
during the daytime and nocturnal animals,
link |
which tend to be awake at night,
link |
the longer the melatonin signal, the more depressed,
link |
not necessarily clinically depressed,
link |
although that can happen,
link |
but the more depressed our systems tend to be.
link |
Reproduction, metabolism, mood,
link |
turnover rates of skin cells and hair cells
link |
all tend to be diminished
link |
compared to the spring and summer months for some,
link |
Northern hemisphere spring and summer months,
link |
or the times in which days are very long
link |
and there's less melatonin that tends to,
link |
in almost all animals, including humans,
link |
more breeding, more hormone elevation of the hormones
link |
that stimulate breeding reproduction and fertility.
link |
Metabolism is up, lipid metabolism, fat burning is up,
link |
protein synthesis is up.
link |
These things tend to correlate with the seasons.
link |
Now, some people are very, very strongly tied to the seasons
link |
they get depressed, clinically depressed in winter
link |
and light therapies are very useful for those people.
link |
Some people love the winter and they're happiest in winter
link |
and they feel kind of depressed in summer,
link |
although that is far more rare.
link |
That doesn't mean depression cannot exist in the summer,
link |
but when we're talking about seasonal depression,
link |
that tends to be true.
link |
It's more depression in winter.
link |
Now there's other things that correlate with seasonality.
link |
Suicide rates tend to be highest in the spring,
link |
not in the winter,
link |
but that has to do with some of the more complicated
link |
and unfortunately tragic aspects of suicide,
link |
which is that oftentimes people will commit suicide,
link |
not at the very depths of their energy levels,
link |
but as they're emerging from those depths of low energy.
link |
So we'll talk about suicidality and mood disorders
link |
in a later podcast season, meaning a month later,
link |
but for now, just understand that everybody
link |
is going through these natural fluctuations
link |
depending on the duration of the melatonin signal.
link |
Now this might lead you to say,
link |
well, then I should just really get as much light
link |
as I can all the time and reduce melatonin
link |
and feel great all the time.
link |
Unfortunately, it doesn't work that way
link |
because melatonin also has important effects
link |
on the immune system.
link |
It has important effects on transmitter systems
link |
in the brain, et cetera.
link |
So everybody needs to figure out for themselves
link |
how much light they need early in the day
link |
and how much light they need to avoid late in the day
link |
in order to optimize their mood and metabolism.
link |
There is no one size fits all prescription
link |
because there is a range of melatonin receptors.
link |
There are a range of everything from metabolic types
link |
to genetic histories, family histories, et cetera.
link |
There is no one size fits all prescription,
link |
but by understanding that light
link |
and extended day length inhibit melatonin
link |
and melatonin tends to be associated
link |
with a more depressed or reduced functioning
link |
of these kinds of activity driving
link |
and mood elevating signals and understanding
link |
that you have some control over melatonin by way of light,
link |
including sunlight, but also artificial light,
link |
that should empower you, I believe,
link |
to make the adjustments that if you're feeling low,
link |
you might ask, how much light am I getting?
link |
When am I getting that light?
link |
Because sleep is also important for restoring mood, right?
link |
So you need sleep.
link |
You can't just crush melatonin across the board
link |
and expect to feel good
link |
because then you're not going to fall asleep
link |
Melatonin not incidentally comes from,
link |
is synthesized from serotonin.
link |
Serotonin is a neurotransmitter that is associated
link |
with feelings of wellbeing provided to proper levels,
link |
but wellbeing of a particular kind,
link |
wellbeing associated with quiescence and calm
link |
and the feeling that we have enough resources
link |
in our immediate kind of conditions.
link |
It's the kind of thing that comes from a good meal
link |
or sitting down with friends or holding a loved one
link |
or conversing with somebody that you really bond with.
link |
Serotonin does not stimulate action.
link |
It tends to stimulate stillness.
link |
Very different than the neuromodulator dopamine,
link |
which is a reward, feel good neuromodulator
link |
that stimulates action.
link |
And actually dopamine is the precursor to epinephrine,
link |
to adrenaline, which actually puts us into action.
link |
It's actually made from dopamine, right?
link |
So you can start to think about light as a signal
link |
that is very powerful for modulating things
link |
like sleep and wakefulness,
link |
but also serotonin levels, melatonin levels.
link |
And I talked about this previously,
link |
but I'll mention once more
link |
that light in the middle of the night reduces dopamine levels
link |
to the point where it can start causing problems
link |
with learning and memory and mood.
link |
That's one powerful reason to avoid bright light
link |
in the middle of the night.
link |
Okay, seasonal rhythms have a number of effects,
link |
but humans are not purely seasonal breeders.
link |
Unlike a lot of animals, we breed all year long.
link |
In fact, there's a preponderance of September babies
link |
in my life, not actual babies,
link |
but people that are born in September,
link |
which means that they were conceived in December.
link |
Without knowing the details, we can fairly assume that.
link |
And December, at least in the Northern hemisphere,
link |
days tend to be shorter and nights tend to be longer.
link |
So clearly humans aren't seasonal breeders,
link |
but there are shifts in breeding and fertility
link |
that exist in humans,
link |
but also much more strongly in other animals.
link |
So seasonal effects vary.
link |
Some of you will experience very strong seasonal effects.
link |
Others of you will not.
link |
I think everybody should be taking care
link |
to get adequate sunlight and to avoid bright light at night
link |
throughout the year, if possible.
link |
Throughout this podcast and in previous episodes,
link |
I've been mentioning neuromodulators,
link |
things like serotonin and dopamine,
link |
which tend to bias certain brain circuits
link |
and things in our body to happen
link |
and certain brain circuits and things in our body
link |
One of the ones I've mentioned numerous times is epinephrine,
link |
which is a neuromodulator that tends to put us into action,
link |
make us want to move.
link |
In fact, when it's released in high amounts
link |
in our brain and body, it can lead to what we call stress
link |
or the feeling of being stressed.
link |
Several people asked me,
link |
what's the difference between epinephrine and adrenaline?
link |
Adrenaline is secreted from the adrenal glands,
link |
which sit right above our kidneys.
link |
Epinephrine is the exact same molecule,
link |
except that it's released within the brain.
link |
And so people use these phrases
link |
or these words rather interchangeably.
link |
Epi means near or on top of sometimes
link |
and any time you see nephron, it means kidney.
link |
So it means near the kidney.
link |
So epinephrine actually means near the kidney.
link |
So it was used originally to describe adrenaline,
link |
but epinephrine and adrenaline are basically the same thing
link |
and they tend to stimulate agitation
link |
and the desire to move.
link |
That's what that's about.
link |
Which brings us to the topic of exercise.
link |
Got a lot of questions about exercise.
link |
What forms of exercise are best for sleeping well?
link |
When should I exercise, et cetera?
link |
There's a lot of individual variability around this,
link |
but I can talk about what I know from the science literature
link |
and what I happen to do myself.
link |
There are basically two forms of exercise
link |
that we can talk about.
link |
Although, of course, I realize
link |
there are many different forms of exercise.
link |
There's much more nuance to this,
link |
but we can talk about cardiovascular exercise
link |
where the idea is to repeat a movement
link |
over and over and over continuously.
link |
So that'd be like running, biking, rowing,
link |
the cycling, this kind of thing.
link |
Or there's a resistance exercise
link |
where you're moving, lifting,
link |
presumably putting down also.
link |
Things of progressively heavier and heavier weight
link |
that you couldn't do continuously for 30 minutes.
link |
So cardiovascular exercise
link |
is typically the more aerobic type exercise
link |
and resistance exercise, of course,
link |
is the more anaerobic type exercise.
link |
And yes, there's variation between the two.
link |
Most studies of exercise have looked at aerobic exercise
link |
because that's basically the thing
link |
that you can get a rat or a mouse to do.
link |
You know what's really weird about rats and mice?
link |
They like to run on wheels so much
link |
that someone actually did this study.
link |
It was published in Science.
link |
They put a wheel, a running wheel,
link |
in the middle of a field
link |
and mice ran to that wheel and ran on the wheel.
link |
It turns out that what they like
link |
is the passage of the visual image of the bars
link |
in front of their face,
link |
which I find kind of remarkable and troubling
link |
because it seems so like trivial.
link |
But anyway, they love aerobic exercise.
link |
And so most of the studies were done on these mice
link |
that love running on wheels.
link |
Whereas so far, it's been challenging to find conditions
link |
in which mice really like to lift weights
link |
or will do it in a laboratory.
link |
So any weight-bearing exercise studies
link |
really have to be done in humans.
link |
And since humans are what we're interested in,
link |
there are some studies looking at these two things
link |
and when they tend to work best.
link |
Now you will see some places aerobic exercise
link |
is best done in the morning
link |
and weight training is best done in the afternoon.
link |
I think there's far more individual variation than that.
link |
I think there are, however,
link |
a couple of windows that the exercise science literature
link |
and the circadian literature points to
link |
as windows related to body temperature
link |
in which performance, injury,
link |
in which performance is optimized,
link |
injury is reduced and so on.
link |
And those tend to be 30 minutes after waking.
link |
And that probably correlates
link |
with the inflection in cortisol associated with waking,
link |
whether or not you've gotten light or not.
link |
Three hours after waking,
link |
which probably correlates to the rise in body temperature,
link |
sometime right around waking.
link |
And the later afternoon, usually 11 hours after waking,
link |
which is when temperature tends to peak.
link |
So some people like to exercise in the morning.
link |
Some people like to exercise in the afternoon.
link |
It really depends.
link |
I think for those of us with very busy schedules,
link |
it's advantageous to be able to do your training
link |
whenever you have the opportunity to do it,
link |
unless you can really control your schedule.
link |
And so I would never want these recommendations
link |
to seem like recommendations.
link |
What I'm really describing is some opportunities
link |
30 minutes after waking,
link |
three hours after waking or 11 hours after waking
link |
has been shown at least in some studies
link |
to optimize performance, reduce injury
link |
and that sort of thing.
link |
But you really have to figure out what works for you.
link |
A note about working out first thing in the morning.
link |
Last time we talked about non-photic phase shifts.
link |
If you exercise first thing in the morning,
link |
your body will start to develop an anticipatory circuit.
link |
There's actually plasticity in these circadian circuits
link |
that will lead you to want to wake up
link |
at the particular time that you exercised the previous
link |
three or four days.
link |
So that can be a powerful tool,
link |
but you still want to get light exposure
link |
because it turns out that light and exercise converge
link |
to give an even bigger wake up signal to the brain and body.
link |
So you might want to think about that.
link |
Some people find if they exercise late in the day,
link |
they have trouble sleeping.
link |
In general, intense exercise does that.
link |
Whereas the kind of lower intensity exercise doesn't.
link |
I found some interesting literature
link |
that talked about sleep need and exercise.
link |
I found this fascinating that if one is waking,
link |
not feeling rested and recovered from,
link |
and yet sleeping the same amount that they typically have,
link |
it's quite possible that the intensity of exercise
link |
in the preceding two or three days is too high.
link |
Whereas if one can't recover,
link |
no matter how much sleep they get,
link |
they're just sleepy all the time,
link |
I realize these things are correlated,
link |
that the volume of training might be too high.
link |
Now, I'm not an exercise scientist.
link |
We should probably get Andy Galpin or somebody else on here
link |
who's really an expert in this kind of stuff.
link |
I do realize as soon as anyone talks about exercise
link |
or nutrition publicly,
link |
they're basically opening themselves up
link |
to all sorts of challenges
link |
because you can basically find support
link |
for almost any protocol in the literature.
link |
What I've looked at was two journals in particular,
link |
International Journal of Chronobiology
link |
and Journal Biological Rhythms, excuse me,
link |
to assess these parameters
link |
that I mentioned just a moment ago,
link |
because the studies tended to be done in humans.
link |
They were fairly recent
link |
and they came from groups that I recognized
link |
as well as knowing that those journals are peer reviewed.
link |
Many of your questions were about neuroplasticity,
link |
which is the brain and nervous system's ability to change
link |
in response to experience.
link |
There was a question that asked whether or not
link |
these really deep biological mechanisms
link |
around wakefulness, time of waking, sleep, et cetera,
link |
were subject to neuroplasticity, and indeed they are.
link |
Some of that plasticity is short-term
link |
and some of it is more long-term.
link |
There's a really good analogy here,
link |
which is if you happen to eat on a very tight schedule
link |
where every day, say at 8 a.m., noon and 7 p.m.
link |
is when you eat your food,
link |
not suggesting you do this,
link |
but let's say you were to do that for a couple of days.
link |
you would start to anticipate those mealtimes
link |
where no matter where you were in the world,
link |
no matter what was going on in your life,
link |
about five to 10 minutes before those mealtimes,
link |
you would start to feel hungry and even a little agitated,
link |
which is your body's way
link |
of trying to get you to forage for food.
link |
And that's because of some peptide signals
link |
that come from the periphery from your body,
link |
things like hypocretinorexin
link |
that signal to the hypothalamus and brainstem
link |
to make you active and alert
link |
and look for food and feel hungry.
link |
So there's kind of an anticipatory circuit
link |
that's a chemical circuit,
link |
but eventually over time, the neurons, the neural circuits
link |
that control hypocretinorexin
link |
would get tuned to the neural circuits
link |
that are involved in eating and maybe even smell and taste
link |
to create a kind of eating circuit
link |
that's unique to your pattern, to your rhythms.
link |
The same thing is true for these waking and exercise
link |
and other schedules, including ultradian schedules.
link |
If you wake up in the morning
link |
and start getting your sunlight,
link |
you start exercising in the morning
link |
or you exercise in the afternoon,
link |
pretty soon your body will start to anticipate that
link |
and start to secrete hormones and other signals
link |
that prepare your body for the ensuing activity
link |
of waking up or going to sleep.
link |
So if you get onto a pattern or a rhythm,
link |
even if that rhythm isn't down to the minute,
link |
you'll find that there's plasticity in these circuits
link |
and it becomes easier to wake up early if that's your thing
link |
or exercise at a particular day if that's your thing.
link |
That's the beauty of neuroplasticity.
link |
A number of people asked,
link |
what can I do to increase plasticity?
link |
And that really comes in two forms.
link |
There's plasticity that we can access in sleep
link |
to improve rates of learning and depth of learning
link |
from the previous day or so.
link |
And there's this NSDR, non-sleep deep rest,
link |
that can be done without sleeping
link |
to improve rates of learning
link |
and depth of retention, et cetera.
link |
So let's consider those both
link |
and you can incorporate these protocols if you like.
link |
Again, these are based on quality peer-reviewed studies.
link |
First, let's talk about learning in sleep.
link |
This is based on some work that I'll provide the reference
link |
for that was published in the journal Science.
link |
Excellent journal.
link |
Matt Walker also talks about some of these studies
link |
done by others in his book, Why We Sleep.
link |
The studies, just to remind you,
link |
are structured the following way.
link |
An individual is brought into a laboratory,
link |
does a spatial memory task.
link |
So there tends to be a screen
link |
with a bunch of different objects popping up on the screen
link |
in different locations.
link |
So it might be a bulldog's face,
link |
there might be a cat, then it might be an apple,
link |
then it might be a pen in different locations.
link |
And that sounds trivially easy,
link |
but with time you can imagine it gets pretty tough
link |
to come back a day later and remember
link |
if something presented in a given location
link |
was something you've seen before
link |
and whether or not it was presented in that location
link |
or a different location.
link |
If you had enough objects and change the locations enough,
link |
this can actually be quite difficult.
link |
In this study, subjects either just went through
link |
the experiment or a particular odor was released
link |
into the room while they were learning,
link |
or a tone was played in the room while they were learning.
link |
And then during the sleep of those subjects
link |
the following night and the following night,
link |
this was done repeatedly for several nights,
link |
the same odor or tone was played
link |
while the subjects were sleeping.
link |
They did this in different stages of sleep,
link |
non-REM sleep and rapid eye movement sleep, REM sleep.
link |
They did this with just the tone in sleep
link |
if the subjects had had the odor, but not the tone,
link |
they did it with putting the tone,
link |
if they had had the odor while learning.
link |
So basically all the controls,
link |
all the things you'd want to see done
link |
to make sure that it wasn't some indirect effect,
link |
some modulatory effect, okay?
link |
And what they found was that providing the same stimulus,
link |
the odor if they smelled an odor or a tone
link |
if the subjects heard a tone while learning,
link |
if they just delivered that odor or tone
link |
while the subjects slept,
link |
rates of learning and retention of information
link |
was significantly greater.
link |
This is pretty cool.
link |
What this means that you can cue the subconscious brain,
link |
the asleep brain to learn particular things better
link |
So how might you implement this?
link |
Well, you could play with this if you want,
link |
I don't see any real challenge to this
link |
provided the odor is a safe one and it doesn't wake you up
link |
and the tone is a safe one and doesn't wake you up.
link |
You could do this by having a metronome for instance,
link |
while learning something,
link |
playing in the background or particular music
link |
and then have that very faintly while you sleep.
link |
So you could apply this if you like and try this.
link |
There are a number of groups,
link |
I think now that are trying this using tactile stimulation.
link |
So slight vibration on the wrist during learning
link |
and then the same vibration on the wrist during sleep.
link |
It does not appear that the sensory modality,
link |
whether or not it's odor or auditory tone
link |
or tactile stimulation, somatosensory stimulation,
link |
whether or not it matters.
link |
It's remarkable because it really shows
link |
that sleep is an extension of the waking state.
link |
We've known that for a long time,
link |
but this really tethers those two
link |
in a very meaningful and actionable way.
link |
So I think I'll report back to you
link |
as I learn more about these studies,
link |
but that's what I know about them at this point.
link |
As long as we're there,
link |
we might as well talk about dreaming
link |
because I got so many questions about dreams.
link |
A couple of people want to ask me what their dreams meant.
link |
Look, I don't even know what my dreams mean half the time.
link |
I occasionally will wake up from a dream and remember it.
link |
If you want to remember your dreams better,
link |
if you're somebody who has challenges
link |
remembering your dreams,
link |
you can set your alarm so that you wake up
link |
in the middle of one of these 90 minute cycles,
link |
which toward morning tend to be occupied
link |
almost exclusively by REM sleep.
link |
Remember early in the night,
link |
you have less REM sleep than later in the night,
link |
but you want to get as much sleep as you can
link |
because that's healthy.
link |
So I don't know that you want to wake yourself up.
link |
Some people find that writing down their thoughts
link |
immediately first thing in the morning
link |
allows them to later spontaneously remember
link |
their dream they had.
link |
There's some literature on that.
link |
The meaning of dreams is a little bit controversial.
link |
Some people believe they have strong meaning.
link |
Other people believe that they can be
link |
just spontaneous firing of neurons
link |
that were active in the waking state
link |
and don't have any meaning.
link |
There are good data to show that when you learn spatial,
link |
new spatial environments,
link |
that there's a replay of those environments,
link |
so-called place cells that fire in your brain
link |
only when you enter a particular environment,
link |
that those are replayed in sleep
link |
in almost direct fashion to the way that
link |
things were activated
link |
when you were learning that spatial task.
link |
Dreams are fascinating.
link |
We're paralyzed during dreams,
link |
which brings us to another question.
link |
Somebody asked about sleep paralysis.
link |
We are paralyzed for much of our sleep, so-called atonia,
link |
presumably so we don't act out our dreams.
link |
Some people wake up and they're still paralyzed.
link |
I've actually had this happen to me,
link |
not very many times, but a few times,
link |
and then they jolt themselves awake.
link |
And it actually is quite terrifying,
link |
I can say from personal experience,
link |
to wake up, be wide awake,
link |
and you cannot move your body at all.
link |
It's really quite frightening.
link |
There are a couple of things
link |
that will increase the intrusion of atonia
link |
into the wakeful state,
link |
which is essentially means you're waking up,
link |
but you can't move.
link |
One is marijuana, THC.
link |
I'm not a marijuana smoker.
link |
I'm not a cop, or I don't know the legality where you live,
link |
so I'm not saying one thing or another about marijuana.
link |
I'm just, the fact that I had that experience
link |
without marijuana means that it can happen regardless.
link |
But marijuana smokers, for whatever reason,
link |
maybe it has something to do with the cannabinoid receptors
link |
or the serotonin receptors downstream
link |
of the motor pathways, I don't know.
link |
I couldn't find any literature on this,
link |
but marijuana smokers report higher frequency
link |
of this kind of paralysis and wakefulness
link |
as you transition from sleep to wakefulness.
link |
I suppose probably one could learn
link |
to get comfortable with it.
link |
For me, it was terrifying
link |
because I'm just used to being able
link |
to move my limbs, fortunately,
link |
and I wasn't able to.
link |
And it's quite a thing, let me tell you.
link |
Okay, some other questions about neuroplasticity.
link |
So the other form of neuroplasticity
link |
is not the neuroplasticity that you're amplifying
link |
by listening to tones or smelling odors in sleep,
link |
but the neuroplasticity that you can access
link |
with non-sleep deep rest.
link |
So NSDR, non-sleep deep rest,
link |
as well as short 20-minute naps,
link |
which are very close to non-sleep deep rest
link |
because people rarely drop into deep states of sleep
link |
during short naps, unless they're very sleep deprived.
link |
NSDR has been shown to increase rates of learning
link |
when done for 20-minute bouts
link |
to match an approximately 90-minute bout of learning.
link |
So what am I talking about?
link |
90-minute cycles are these ultradian cycles
link |
that I've talked about previously.
link |
And we tend to learn very well
link |
by taking a 90-minute cycle,
link |
transitioning into some focus mode early in the cycle
link |
when it's hard to focus,
link |
and then deep focus and learning
link |
feels almost like agitation and strain.
link |
And then by the end of that 90-minute cycle,
link |
it becomes very hard to maintain focus
link |
and learn more information.
link |
There's a study published in Cell Reports last year,
link |
great journal, excellent paper,
link |
showing that 20-minute naps or light sleep
link |
of a sort of non-sleep deep rest
link |
taken immediately after or close to,
link |
it doesn't have to be immediately
link |
after you finish the last sentence of learning
link |
or whatever it is or bar of music.
link |
But a couple of minutes after,
link |
transitioning to a period of non-sleep deep rest
link |
where you're turning off the analysis of duration,
link |
path, and outcome has been shown to accelerate learning
link |
to a significant degree,
link |
both the amount of information
link |
and the retention of that information.
link |
So that's pretty cool because this is a cost-free,
link |
drug-free way of accelerating learning
link |
without having to get more sleep,
link |
but simply by introducing these 20-minute bouts.
link |
I would encourage people if they want to try this
link |
to consider the 20 minutes per every 90 minutes
link |
of ultradian learning cycle.
link |
There you're incorporating
link |
a number of different neuroscience-backed tools,
link |
90-minute cycles for focused learning,
link |
it could be motor, it could be cognitive,
link |
it could be musical, whatever,
link |
and then transition to a 20-minute
link |
non-sleep deep rest protocol.
link |
Just want to cue you the fact that in last episode
link |
in the caption on YouTube,
link |
we provided links to two different
link |
yoga nidra non-sleep deep rest protocols
link |
as well as hypnosis protocols that are clinically backed
link |
from my colleague David Spiegel
link |
at Stanford Psychiatry Department.
link |
All those resources are free.
link |
There are also a lot of other hypnosis scripts out there.
link |
I like the ones from Michael Sealy, S-E-A-L.
link |
I think it's E-Y, although maybe it's just L-Y.
link |
You can find them easily on YouTube.
link |
Clinical hypnosis scripts, meaning not staged hypnosis.
link |
They're not designed to get you to do anything.
link |
In fact, they're just designed
link |
to help rewire your brain circuitry.
link |
Now, how does hypnosis work that way?
link |
This has a lot to do with sleep
link |
because it engages neuroplasticity
link |
by bringing together two things
link |
that normally are separate from one another.
link |
One is the alert focused wakeful state
link |
where you activate the learning.
link |
And then there's the deep rest
link |
where the actual reconfiguration of the neurons
link |
and synapses takes place.
link |
Hypnosis brings both the focus and the deep rest component
link |
into the same compartment of time.
link |
It's a very unique state in that way.
link |
So hypnosis kind of maximizes the learning bout
link |
and the non-sleep deep rest bout and combines them.
link |
But of course that requires some guidance
link |
from a script or from a hypnotist,
link |
clinically trained hypnotist,
link |
and it becomes hard to acquire detailed information.
link |
It's more about shifts in state like fear to states of calm
link |
or smoking to quitting smoking,
link |
anxiety around a trauma to release of anxiety
link |
around a trauma rather than specific information
link |
learned in hypnosis, okay?
link |
So hypnosis seems more about modulating the circuits
link |
that underlie state as opposed to specific information.
link |
Although I would not be surprised
link |
if there weren't certain forms of hypnosis
link |
that could increase retention
link |
and learning of specific information,
link |
but I'm not aware of any of those protocols out there yet.
link |
Which brings us to the next thing about learning
link |
and plasticity, which is nootropics, AKA smart drugs.
link |
This is a big topic that Sai was a Sai of concern
link |
about how to address nootropics in a thorough enough
link |
but thoughtful enough way.
link |
Look, I have a lot of thoughts about nootropics.
link |
First of all, it means smart drugs, I believe.
link |
And I don't like that phrase
link |
because let's just take a step back
link |
and think about exercise.
link |
Here you say, I want to be more physically fit.
link |
What does that mean?
link |
Does it mean, I would ask for more specificity.
link |
I'd say, do you want to be stronger?
link |
Okay, maybe you need to lift heavier objects progressively.
link |
Do you want more endurance?
link |
Very different protocol to access endurance.
link |
Do you want flexibility?
link |
Do you want explosiveness or suppleness?
link |
Huge range of things that we call physical fitness.
link |
Maybe you want all of those.
link |
If we were talking about emotional fitness,
link |
we would say, well, an ability to feel empathy,
link |
but probably also to disengage from empathy
link |
because you don't want to be tethered
link |
to other people's emotions all the time.
link |
That's not healthy either.
link |
You would think about being able
link |
to access a range of emotions,
link |
but for some people their range into the sadness regime
link |
is really quite vast,
link |
but their range into the happiness regime
link |
might be kind of limited.
link |
For other people who are in a manic state,
link |
it might be they can access all the happy stuff,
link |
but not the sadder stuff.
link |
So I'm speaking by way of analogy here,
link |
but if we say, we're talking about cognitive abilities,
link |
we have to ask, okay, creativity, memory.
link |
We tend to associate intelligence with memory.
link |
I think this goes back to like spelling bees or something,
link |
the ability to retain a lot of information
link |
and just regurgitate information,
link |
which will get you some distance in some disciplines of life
link |
but it won't allow you creative thinking.
link |
It's necessary for creative thinking.
link |
You need a knowledge base, right?
link |
You can't just look up everything on Google
link |
despite what certain educators or so-called educators say.
link |
You need a database so that you have the raw materials
link |
with which to be creative.
link |
So necessary to have memory, but not sufficient
link |
to be creative, right?
link |
The creative could have a poor memory for certain things,
link |
but certainly not for everything.
link |
They can't have anterograde and retrograde amnesia.
link |
They'd be like the goldfish that every time around the tank,
link |
it can't remember where it's at.
link |
I actually don't know that they've ever done
link |
that experiment by the way, but you know,
link |
so no disrespect to goldfish, but you know.
link |
So you get the idea, you've got creativity,
link |
you have memory, you have the ability to task switch, right?
link |
You have the ability to strategy develop
link |
and strategy implement.
link |
So the problem I have with the concept of a nootropic
link |
or a smart drug is it's not specific
link |
as to what cognitive algorithm you're trying to engage.
link |
We need more specificity.
link |
That said, there are elements to learning
link |
that we've discussed here before that are very concrete.
link |
Things like the ability to focus and put the blinders
link |
on to everything else that's happening around you
link |
and in your head, mainly, right?
link |
Distractions about things you should be doing,
link |
could be doing, or might be doing
link |
and focus on what you need to do.
link |
And then that's required for triggering
link |
the acetylcholine neuromodulator
link |
that will then allow you to highlight
link |
the particular synapses that will then later change in sleep.
link |
So no nootropic allows you to bypass the need
link |
for sleep and deep rest.
link |
That's important to understand.
link |
So I daydream about a day
link |
when people will be able to access compounds
link |
that are safe, that will allow them to learn better,
link |
meaning to access information, focus better,
link |
as well as to sleep better and activate the plasticity
link |
from the learning bout.
link |
Right now, most nootropics tend to bundle
link |
a bunch of things together.
link |
Most of them include some form of stimulant, caffeine.
link |
Episode two, I tell you more,
link |
probably than you ever wanted to know
link |
about caffeine adenosine and how that works.
link |
So refer there for how caffeine works.
link |
But stimulants will allow you to increase focus
link |
up to a particular point.
link |
If you have too little alertness in your system,
link |
you can't focus too much.
link |
However, you start to cliff and focus drifts, okay?
link |
So you can't just ingest more stimulant to be more focused.
link |
It doesn't work that way.
link |
Most nootropics also include things that increase
link |
or are designed to increase acetylcholine,
link |
things like alpha-GPC and other things of that sort.
link |
And indeed, there's some evidence
link |
that they can increase acetylcholine.
link |
I refer you again to examine.com, the website,
link |
to evaluate any supplements or compounds for their safety
link |
and their effects in humans and animals.
link |
Free website, as well as with links to studies.
link |
So we need the focus component.
link |
We need the alertness component.
link |
The alertness component comes from epinephrine,
link |
traditionally from caffeine stimulation.
link |
The acetylcholine stimulation traditionally comes
link |
from choline donors or alpha-GPC, things of that sort.
link |
And then you would want to have some sort of off switch
link |
because anything that's going to really stimulate
link |
your alertness that then provides a crash,
link |
that crash is not a crash into the deep kind
link |
of restful slumber that you would want for learning.
link |
It's a crash into the kind of,
link |
let's just call it lopsided sleep, meaning it's deep sleep,
link |
but it lacks certain spindles and other elements
link |
of the physiology, sleep spindles,
link |
that really engage the learning process
link |
and the reconfiguration of synapses.
link |
So right now, my stance on nootropics is that maybe,
link |
maybe for occasional use, provided it's safe for you,
link |
I'm not recommending it, but in general,
link |
it tends to use more of a shotgun approach
link |
than is probably going to be useful
link |
for learning and memory in the long run.
link |
A lot of people ask about modafinil or armodafinil,
link |
which was designed for treatment of narcolepsy.
link |
So right there, it tells you it's a stimulant.
link |
And yes, there is evidence
link |
it will improve learning and memory.
link |
Modafinil is very expensive.
link |
Last time I checked, armodafinil,
link |
I think is the recent released generic version of this
link |
that's far less expensive.
link |
Most of these things look a lot like amphetamine
link |
and many of them have the potential for addiction
link |
or can be habit forming, but more importantly,
link |
a lot of those things also can create metabolic effects
link |
by disruption to insulin receptors and so forth.
link |
So you want to approach those
link |
with a strong sense of caution.
link |
Now, there are the milder things that act as nootropics.
link |
I mentioned some of them like alpha-GPC.
link |
Some people like ginkgo.
link |
Ginkgo gives me vicious headaches, so I don't take it.
link |
So, you know, people really differ.
link |
Last podcast, I recommended magnesium threonate
link |
if you were exploring supplements.
link |
I'm not recommending anything directly.
link |
I'm just saying if you're exploring supplements,
link |
magnesium threonate seems among the magnesiums
link |
to be one of the more bioavailable and useful for sleep.
link |
I recommend it actually to a good friend of mine.
link |
It gave him, at very low dose,
link |
he had stomach issues with it.
link |
He just had to simply stop taking it.
link |
So there's variability there.
link |
You just, it gave him some stomach cramping
link |
and just didn't feel good on it.
link |
Stopped it, he felt better.
link |
Other people take magnesium threonate and feel great.
link |
I was asked, do magnesium need to be taken
link |
with or without food, daytime or before sleep?
link |
If you're going to go that route,
link |
it should be taken 30 to 60 minutes before sleep
link |
because it's designed to make you sleepy.
link |
And I'm not aware that it has to be taken with food,
link |
but again, all of this has to be run by your doctor
link |
and this is your healthcare to govern.
link |
Not, these are not strict recommendations, so look into it.
link |
But magnesium threonate,
link |
most people have recommended it
link |
to have benefit from it tremendously.
link |
Some people can't tolerate it, so you have to find out.
link |
There were a number of questions about other supplements
link |
designed to access deep sleep
link |
in part to access neuroplasticity,
link |
but now I'm just sort of transitioning
link |
from neuroplasticity to these compounds
link |
that can regulate sleep.
link |
One of them that I discussed at the end of the last podcast,
link |
I got a lot of questions about,
link |
is apigenin, A-P-I-G-E-N-I-N.
link |
Apigenin, if you look in the literature,
link |
the way it works is it increases some of the enzymes
link |
associated with GABA metabolism.
link |
It actually, GABA is an inhibitory neurotransmitter.
link |
It's the neurotransmitter that is increased
link |
after a couple drinks containing alcohol
link |
and that shut down the forebrain.
link |
Apigenin is a derivative of the chamomile.
link |
I think the proper pronunciation of this
link |
is matricaria chamomila,
link |
although I always feel like I should be using
link |
a Spanish accent whenever I say something like that.
link |
Other related things that impact the GABA system
link |
and increase GABA are things like passion flower,
link |
which is passiflora incurata.
link |
I don't know why the Italian, is that Italian?
link |
Anyway, my Italian colleagues, please forgive me.
link |
I have some very close Italian friends
link |
and colleagues in Genoa.
link |
I butchered the Italian, sorry.
link |
In any event, apigenin and passion flower
link |
found in a lot of supplements
link |
designed to increase sleepiness and sleep
link |
and they work presumably because they increase GABA.
link |
Actually, they work on chloride channels
link |
rather than give you a whole lecture
link |
on membrane biophysics and neurons.
link |
I'll just say that when neurons are really active,
link |
it's because sodium ions, salt, rushes into the cells
link |
and causes them to fire electrically.
link |
The cells tend to become less active as more chloride,
link |
which is a negatively charged ion.
link |
This is probably taking some of you back
link |
to either the wonderful times or traumas
link |
of high school physics.
link |
The chloride is negatively charged
link |
so it tends to make cells less electrically positive
link |
because it carries a negative charge
link |
and hyperpolarizes the neuron.
link |
So apigenin works through these,
link |
increasing the activity of these chloride channels.
link |
Passion flower works by increasing the activity
link |
of these chloride channels and GABA transmission.
link |
It tends to increase this inhibitory neurotransmitter
link |
that shuts off our thinking,
link |
our analysis of duration, path, and outcome.
link |
So if you're going to explore these things,
link |
I suggest you at least know how they work.
link |
You at least go to examine.com
link |
that you talk to your doctor about them.
link |
Some people asked about serotonin
link |
for getting to sleep and staying asleep.
link |
Now I understand the rationale here.
link |
Just like I understand the rationale
link |
of taking something like mucuna purines or L-DOPA
link |
to increase dopamine.
link |
But sometimes what works on paper
link |
doesn't really work in the real world.
link |
I personally have tried taking a supplement
link |
which was L-Tryptophan,
link |
which is the precursor to serotonin or 5-HTP,
link |
which is designed to increase,
link |
it is serotonin basically.
link |
You're just one biochemical step away
link |
from taking actual serotonin.
link |
And I'll be honest,
link |
the sleep that I had with increased serotonin
link |
by way of tryptophan or 5-HTP was dreadful.
link |
I fell asleep almost immediately.
link |
You say, well, that's great.
link |
And 90 minutes later I woke up
link |
and I couldn't sleep almost for 48 hours.
link |
I have a pretty sensitive system to certain things
link |
and not to other things.
link |
Some people love these things.
link |
So you really have to be thoughtful and explore them
link |
with that kind of awareness of being thoughtful
link |
and realizing that what works for you
link |
might not work for everybody
link |
and what works for everybody might not work for you.
link |
Okay, I'd like to continue
link |
by talking about the role of temperature
link |
in sleep, accessing sleep, staying asleep and wakefulness.
link |
But first I want to tell a joke
link |
because I think this joke really captures
link |
some of the critical things to understand
link |
about any self experimentation that you might do.
link |
So this is a story that was told to me
link |
by a colleague of mine
link |
who's now a professor of Caltech, not to be named.
link |
So there's a scientist and they're in their lab
link |
and they're trying to understand
link |
how the nervous system works.
link |
So they go over to a tank and they pick up a frog
link |
and they take the frog and they put it down on the table
link |
and they clap and the frog jumps.
link |
So they think for a while, they pick up the frog, okay.
link |
They go over to the cabinet
link |
and they take out a little bit of a paralytic drug
link |
and they inject it locally into the back leg,
link |
set it down and clap and the frog jumps,
link |
but it kind of like jumps to the side a little bit.
link |
they inject the paralytic into the other back leg.
link |
The frog jumps, but it really doesn't jump well that time,
link |
it kind of drags itself forward.
link |
So they pick it up and they inject the paralytic
link |
into the remaining two legs.
link |
They set it down and they clap and the frog doesn't jump.
link |
They go, oh my goodness, the legs are used for hearing.
link |
Now they publish the paper.
link |
Paper comes out in a great journal, news releases.
link |
It's a really big deal.
link |
Their career takes off.
link |
20 years later, a really smart graduate student comes along
link |
and says, yeah, but that's loss of function.
link |
Doesn't really show gain of function.
link |
So let's take a closer look.
link |
So they repeat the first experiment and it checks out.
link |
Everything happens the same way,
link |
but then they take the frog and they inject a drug
link |
into all four legs that turns off the paralytic, right?
link |
It's an antagonist.
link |
They set the frog down, they clap and the frog jumps.
link |
They go, oh my goodness, it's true.
link |
The legs really are for hearing.
link |
Now, first of all, I want to make the point
link |
that this is not to illustrate
link |
that science is not a good practice.
link |
We need to do loss of function
link |
and gain in function experiments,
link |
but just to show that correlation and causation
link |
You need to do a variety of control experiments
link |
and you really need to figure out what works for you.
link |
And so while science can provide answers
link |
about what works under very controlled conditions,
link |
it doesn't and can never address all the situations
link |
in which a given compound, a given practice
link |
will or won't work.
link |
And it's not just individual variability,
link |
it's that there are a number of different factors.
link |
You of course know that light can activate
link |
and shift your circadian rhythm,
link |
but so can exercise, so can food.
link |
The last point I want to make is an important one,
link |
which is that no frogs were hurt in the telling of this joke.
link |
Okay, so let's continue.
link |
I want to talk about temperature.
link |
Temperature is super interesting
link |
as it relates to circadian rhythms
link |
and wakefulness and sleep.
link |
First, let's take a look at what's happening
link |
to our body temperature across each 24 hour cycle.
link |
In general, our temperature tends to be lowest
link |
right around 4 a.m. and starts creeping up around 6 a.m.,
link |
8 a.m., and peaks sometime between 4 p.m. and 6 p.m.
link |
Now that varies from person to person,
link |
but in general, if we were to continuously monitor
link |
or occasionally monitor temperature,
link |
that's what we would see.
link |
Now what's interesting is that even in the absence
link |
of any light cues or meal cues, we would have a shift.
link |
We would have an oscillation or a rhythm in our temperature
link |
that would go from high to low.
link |
This is why the idea that we're all 96.8
link |
and that's our correct temperature, forget that.
link |
That is no longer true.
link |
It never was true.
link |
It depends on what time of day you measure temperature.
link |
However, there is a range which is within normal range.
link |
I think most of us associate fever
link |
with somewhere around 100, 101, 103.
link |
That's concerning.
link |
And we will be very concerned
link |
if temperature dropped too low as well.
link |
The way that the temperature rhythm that's endogenous,
link |
that's within us and rhythmic no matter what,
link |
the way it gets anchored to the pattern I described before
link |
of being lowest at 4 a.m. and increasing again
link |
around through the day until about 4 to 6 p.m.
link |
is by way of entrainment or matching to some external cue,
link |
which is almost always going to be light, but also exercise.
link |
Now you may have experienced this temperature rhythm
link |
and how quickly it can become unentrained
link |
or it can fall out of entrainment.
link |
Here's an experiment I wouldn't want you to do
link |
but you've probably experienced this before
link |
where you wake up, it's sunny outside
link |
and maybe you have some email or some things to take care of
link |
or maybe you didn't sleep that well the night before
link |
and so you stay indoors.
link |
You don't change anything about your breakfast.
link |
You don't change anything about your within home temperature
link |
or anything like that.
link |
And somewhere right around 10 or 11 o'clock
link |
you start feeling kind of chilled, like you're cold.
link |
Well, what happened was the oscillators,
link |
the clocks in your various tissues
link |
that are governed by temperature and circadian rhythm
link |
are starting to split away
link |
from your central clock mechanisms.
link |
So it's actually important
link |
that your temperature match day length.
link |
Now there's another way in which temperature matches
link |
or daytime, excuse me.
link |
There's also an important way
link |
in which temperature matches day length.
link |
In general, as days get longer, it tends to be hotter out.
link |
Not always, but in general, that's the way it is.
link |
And as days get shorter, it tends to be colder outside.
link |
So temperature and day length are also linked.
link |
Metabolically they're linked,
link |
biologically they're linked, excuse me,
link |
and atmospherically they're linked
link |
for the reasons that we talked about before
link |
about duration of day length
link |
and other climate features and so forth.
link |
So one of the most powerful things
link |
about setting your circadian rhythm properly
link |
is that your temperature will start to fall
link |
into a regular rhythm.
link |
And that temperature has a very strong effect
link |
on things like metabolism
link |
and when you will feel most willing
link |
and interested in exercising.
link |
Typically the willingness to exercise and engage
link |
in any kind of activity, mental or physical,
link |
is going to be when that rise in temperature is steepest,
link |
when the slope of that line is greatest.
link |
That's why 30 minutes after waking
link |
is one of those key windows,
link |
as well as three hours after waking.
link |
And then when temperature actually peaks,
link |
which is generally, generally about 11 hours after waking.
link |
So this is why we say that temperature
link |
and circadian rhythm are linked,
link |
but they're actually even more linked than that.
link |
We've talked before about how light enters the eye,
link |
triggers activation of these melanopsin cells,
link |
which then triggers activation
link |
of the suprachiasmatic nucleus,
link |
the master circadian clock.
link |
And then I always say the master circadian clock
link |
informs all the cells and tissues of your body
link |
and puts them into a nice cohesive rhythm.
link |
But what I've never answered
link |
was how it actually puts them into that rhythm.
link |
And it does it two ways.
link |
One is it secretes a peptide.
link |
A peptide is just a little protein
link |
that floats through the bloodstream
link |
and signals to the cells, okay,
link |
we're tuning your clock kind of like a little,
link |
you know, in a watch store,
link |
the watch store owner would tune the clocks.
link |
But the other way is it synchronizes the temperature
link |
under which those cells exist.
link |
So temperature is actually the effector
link |
of the circadian rhythm.
link |
Now, this is really important
link |
because changes in temperature by way of exercise,
link |
by way of eating, but especially by way of exercise
link |
can start to shift our circadian rhythm pretty dramatically.
link |
But let's even go to a more extreme example.
link |
Nowadays, there's some interest in cold showers
link |
Not everybody is doing this, I realize.
link |
People seem to either love this or hate this.
link |
I don't mind the cold dunk thing.
link |
I get regular about this from time to time and I'll do it.
link |
I haven't been doing it recently.
link |
It's always painful to do the first couple of times
link |
and then you get kind of used to it.
link |
However, I've taken people to a cold dunk or an ice bath.
link |
I have a family member
link |
who wouldn't get in literally past her toes.
link |
She was like, this is just too aversive for me.
link |
Some people really like the cold, people very tremendously.
link |
Getting into an ice bath is very interesting
link |
because you have a rebound increase in thermogenesis.
link |
Now, you should know from the previous episode
link |
that as that temperature increases,
link |
it will shift your circadian rhythm
link |
and which direction it shifts your circadian rhythm
link |
will depend on whether or not you're doing it
link |
during the daytime or late in the day.
link |
If you do it after 8 p.m.,
link |
it's going to make your day longer, right?
link |
Because your body and your central clocks
link |
are used to temperature going up early in the day
link |
and throughout the day and peaking in the afternoon.
link |
If you then increase that further
link |
or you simply increase it over its baseline at 8 p.m.
link |
after temperature was already falling,
link |
even if it's just by a half a degree or a couple of degrees
link |
or you do that with exercise, doesn't have to be
link |
with the ice bath, you are extending,
link |
you are shifting forward,
link |
you're phase delaying your clock,
link |
you're convincing your clock
link |
and therefore the rest of your body
link |
that the day is still going, right?
link |
You're giving it the perception,
link |
the cellular and physiological perception
link |
that the day is getting longer
link |
and you will want to naturally stay up later
link |
and wake up later.
link |
Now, you might say, wait, I do an ice bath late at night
link |
and I feel great and I fall deeply asleep.
link |
Well, cold can trigger the release of melatonin.
link |
There's a rebound increase in melatonin.
link |
So that could be the cause of that effect.
link |
You have to see what works for you.
link |
But if you do the ice bath early in the day
link |
and then get out, you will experience a more rapid rise
link |
or cold shower early in the day,
link |
a more rapid rise in your body temperature
link |
that will phase advance your clock
link |
and make it easier to get up early the following day.
link |
So for those of you that are having trouble getting up
link |
and this is going to almost sound laughable,
link |
but a cold shower first thing in the morning
link |
But that's waking you up in the short term
link |
because of a different mechanism
link |
which I'll talk about in a moment.
link |
But it also is shifting your clock.
link |
It's phase advancing your clock
link |
in a way that makes you more likely to get up earlier
link |
the next day, okay?
link |
So in other words, increasing your temperature
link |
by getting in an ice bath or cold shower or exercising
link |
which causes a compensatory increase in body temperature.
link |
Think about the normal pattern of body temperature,
link |
low around 4.35 AM, starts to peak right around waking,
link |
start, excuse me, starts to increase right around waking,
link |
then steep slope, steep slope to a peak around 4 to 6 PM
link |
and then drops off.
link |
If you introduce an increase in body temperature
link |
by way of cold exposure early in the day,
link |
let's say 6 AM or 5 AM if you're masochistic enough
link |
to get into a cold shower at that time, more power to you,
link |
it's going to make you want to wake up about half hour
link |
to an hour earlier the next day than you normally would.
link |
Whereas if you do it while your temperature is falling,
link |
it will tend to delay and make your body perceive
link |
as if the day is getting longer.
link |
These are phase advances and phase delays.
link |
We're going to get into this in far more detail
link |
when we talk about jet lag and shift work in episode four
link |
as well as other things.
link |
But temperature is, again, it's not just one tool
link |
to manipulate wake up time and circadian rhythm
link |
and metabolism, it is the effector.
link |
It is the way that the central circadian clock
link |
impacts all the cells and tissues of your body.
link |
If you want to read further about this
link |
and you're really curious about the role of temperature,
link |
work by Joe Takahashi,
link |
who used to be at Northwestern University
link |
and is now at UT Southwestern in Dallas,
link |
incredible scientist and has really worked out
link |
a lot of the mechanisms around temperature
link |
and circadian rhythms.
link |
You can just Google his name
link |
and you'll see a whole bunch of studies there.
link |
I want to talk about cold and cold exposure
link |
because there's a great misconception about this
link |
that actually you can leverage once you understand
link |
how to use cold to either increase thermogenesis
link |
and fat loss, metabolism,
link |
or you can use it for stress mitigation and mood.
link |
And it really depends on one simple feature
link |
of how you approach the ice bath or cold shower.
link |
If you get into an ice bath or cold shower
link |
and you are calming yourself,
link |
you're actively calming the autonomic nervous system,
link |
maybe through some deep breathing,
link |
maybe through visualization, maybe you sing a song.
link |
People do this stuff.
link |
They use various tools.
link |
Some people find paying attention to an external stimulus
link |
Thinking about something, not the experience of the cold.
link |
Other people find that directly experiencing the cold
link |
in its most intense form and kind of going into the cold,
link |
quote unquote, is the best way to approach it.
link |
It really varies for people.
link |
There's no right or wrong way to go about this.
link |
But the goal of using cold exposure for stress inoculation
link |
and to raise your stress threshold,
link |
to be able to tolerate heightened levels
link |
of real life stress, not the ice bath,
link |
but real life stress like work stress
link |
and relational stress, et cetera,
link |
is by suppressing the activation
link |
of the so-called sympathetic nervous system,
link |
meaning the alertness or stress system.
link |
That involves buffering
link |
or trying to resist the shiver response.
link |
The shiver response is an autonomic response
link |
designed to generate heat, presumably,
link |
and actually that is what it does,
link |
in order to counter the cold.
link |
So when you use cold exposure
link |
and you're kind of muscling through it
link |
or you're learning to relax within it
link |
as a form of stress inoculation,
link |
that's great and works quite well for that purpose.
link |
And there's a reason why cold exposure is used
link |
in a variety of forms of military stress inoculation,
link |
most famous of which of course is the Navy Seal Buds Test,
link |
really, which is screening procedure for becoming a seal,
link |
involves a lot of exposure to cold water.
link |
However, if you're interested in using cold exposure
link |
for fat loss and thermogenesis,
link |
you want to do the exact opposite thing.
link |
There was a paper published in Nature two years ago,
link |
which showed that cold-induced shiver,
link |
the actual physical shiver,
link |
activates the release of a chemical in the body
link |
from muscle called succinate, S-U-C-C-I-N-A-T-E.
link |
Succinate travels in the bloodstream
link |
and then goes and activates a particular category of fat,
link |
not the typical kind of pink or white fat
link |
that we think of as like blubber in humans,
link |
the stuff that people seem to generally want less of,
link |
except for those genetic freaks
link |
that seem to have none of it,
link |
depending on what they consume.
link |
Brown fat is called brown fat
link |
because it's actually dark under the microscope.
link |
It's rich with mitochondria,
link |
and it exists mostly between the scapulae
link |
and in the upper neck,
link |
and it generates thermogenesis and heat in the body.
link |
It's rich with a certain category of adrenergic receptor.
link |
Incidentally, epinephrine binds to adrenergic receptors.
link |
These brown fat cells increase metabolism.
link |
It's called brown fat thermogenesis
link |
and cause fat burning,
link |
burning of other kinds of fat, the pink and white fat.
link |
So what does this all mean?
link |
This means if you want to use the ice bath
link |
in order to increase metabolism, shiver away.
link |
If you want to use the ice bath or cold shower
link |
in order to stress inoculate, resist the shiver
link |
and learn to stay calm or quote unquote muscle through it.
link |
that anyone's ever really talked about this publicly
link |
because I think the data are so new,
link |
and I think that people assume
link |
that the ice bath or cold exposure is just one thing.
link |
Here, I've talked about it three ways
link |
to shift your circadian rhythm
link |
depending on whether or not you're doing it early in the day
link |
while your temperature is still rising or at its peak
link |
or after that peak in order to extend the perception
link |
of your day as continuing
link |
and make you want to go to sleep later and wake up later.
link |
Now, and then the third way of course
link |
is to either activate brown fat thermogenesis
link |
and increase metabolism.
link |
I suppose the fourth way would be
link |
to increase stress tolerance or stress threshold, okay?
link |
But remember temperature is the effector
link |
of circadian rhythms.
link |
Light is the trigger.
link |
The suprachiasmatic nucleus is the master circadian clock
link |
that mediates all these changes.
link |
Also influenced by non-photic influence
link |
like exercise and feeding and things of that sort,
link |
but temperature is the effector.
link |
Now, you can also shift your circadian rhythm with eating.
link |
When you travel and you land in a new location
link |
and your schedule is inverted 12 hours,
link |
one way that we know you can shift your rhythm more quickly
link |
is to get onto the local meal schedule.
link |
Now, that probably has to do with two effects.
link |
One are changes in temperature,
link |
eating-induced increases in body temperature.
link |
Now you should understand why that would work.
link |
As well as eating has this anticipatory secretion
link |
of beta of hypercretinorexin
link |
that I talked about it earlier.
link |
So if this is getting a little too down in the weeds,
link |
don't worry about it.
link |
I will get more into this in episode four
link |
of how to shift one's rhythm,
link |
but I would love for people to understand
link |
that light and temperature are the real heavy duty levers
link |
when it comes to moving your circadian rhythm
link |
and sleep times and activity schedules.
link |
And exercise and feeding can help,
link |
but really temperature and light
link |
with light being the primary one are the most important
link |
when it comes to sleep and wakefulness.
link |
Many people asked questions about food and neurotransmitters
link |
and how those relate to sleep, wakefulness, and mood,
link |
which is essentially 25 hours of content for me to cover,
link |
but I'm going to try and distill out
link |
the most common questions.
link |
We've talked a lot about neuromodulators
link |
like dopamine, acetylcholine, and norepinephrine.
link |
You may notice in those discussions
link |
that the precursors to say serotonin is tryptophan.
link |
Tryptophan actually comes from the diet.
link |
It comes from the foods that we eat.
link |
Tyrosine is the precursor to dopamine.
link |
It comes from the foods that we eat.
link |
And then once we ingest them,
link |
those compounds circulate to a variety
link |
of different cells and tissues,
link |
but it is true that our food
link |
and the particular foods we eat
link |
can influence things like neuromodulator levels
link |
It's not the only way
link |
because there are also enzymes and biochemical pathways
link |
that are going to regulate
link |
how much tyrosine gets converted into dopamine.
link |
And there are elements of the dopaminergic neurons,
link |
the dopamine neurons themselves that are electrical
link |
that have influence on this as well.
link |
But there are a couple fair assumptions that we can make.
link |
First of all, nuts and meats, in particular red meats,
link |
tend to be rich in things like tyrosine, right?
link |
That tells you right there
link |
that because tyrosine is the precursor of dopamine
link |
and dopamine is the precursor of norepinephrine
link |
that those foods tend to lend themselves
link |
toward the production of dopamine and epinephrine
link |
and the sorts of things
link |
that are associated with wakefulness.
link |
Now, of course, the volume of food that we eat
link |
also impacts our wakefulness.
link |
If we eat a lot of anything,
link |
whether or not it's ribeye, steaks, rice, or cardboard,
link |
please don't eat cardboard,
link |
your stomach, if it's very distended,
link |
will draw a lot of blood into your gut
link |
and you will divert blood from other tissues
link |
and you'll become sleepy.
link |
So it's not just about food content,
link |
it's also about food volume, all right?
link |
Fasting states generally are associated
link |
with more alertness, epinephrine, and so forth.
link |
And fed states are generally associated
link |
with more quiescence and relaxation,
link |
serotonin, and the kind of things
link |
that lend themselves more towards sleep
link |
and less toward alertness.
link |
Foods that are rich in tryptophan
link |
tend to be things like white meat turkey,
link |
also complex carbohydrates.
link |
So if you like, you can start experimenting,
link |
depending on what foods you eat,
link |
you can start experimenting with carbohydrate-rich meals
link |
for accessing sleep and more depth of sleep.
link |
This is actually something that I personally do.
link |
I tend to eat pretty low carb-ish during the day.
link |
I actually fast until about noon,
link |
not because I have to work to do that,
link |
but because I'd rather just drink caffeine
link |
and water during that time.
link |
And then sometime around noon,
link |
I can't take it anymore and I'm hungry.
link |
And I eat and I try and eat low carb-ish
link |
unless I've worked out extremely hard
link |
in the previous two hours, which I rarely do,
link |
although I do sometimes.
link |
And that meal is then designed to prolong
link |
my period of wakefulness into the late afternoon.
link |
And then sometime around dinnertime,
link |
which for me is around 6.30, 7 p.m, 8 p.m,
link |
sometimes as late as 9 p.m,
link |
I tend to eat things like white meat, fish, pastas, rice,
link |
and that kind of thing.
link |
My favorite food of all for accessing tryptophan
link |
is actually a starch.
link |
It's actually a vegetable and it's the croissant,
link |
which is my favorite vegetable.
link |
I don't eat those all the time, but I love them.
link |
And they seem to increase dopamine as well.
link |
Never actually done the mass spectrometry on a croissant,
link |
but they definitely increase tryptophan
link |
and relaxation for me.
link |
In all seriousness, low carbohydrate
link |
slash fasted slash ketogenic diets
link |
tend to lend themselves toward wakefulness
link |
by way of increasing epinephrine, norepinephrine,
link |
adrenaline, dopamine, and things of that sort.
link |
Carbohydrate-rich meals,
link |
and I suppose we should talk about meals as opposed to diet,
link |
tend to lend themselves more toward tryptophan, serotonin,
link |
and more lethargic states.
link |
There is very limited evidence that I am aware of
link |
that carbohydrates should be eaten at one time a day
link |
as it relates to metabolism, et cetera.
link |
I'm sure that will open up a certain amount of debate.
link |
If you work out very hard and you deplete glycogen,
link |
then this all changes.
link |
So some people are working out very hard
link |
in depleting glycogen, other people are not.
link |
That gets way outside the context
link |
of this particular podcast.
link |
But yes, indeed, different foods can bias
link |
different neuromodulators
link |
and thereby can modulate our waking
link |
or our feelings of lethargy and sleepiness.
link |
There are a couple of effects of food that are independent,
link |
or I should say a couple of effects of eating
link |
because the food won't do it
link |
when it's sitting across the table,
link |
but of eating that are powerful
link |
for modulating circadian rhythm, wakefulness, et cetera.
link |
And that's because every time we eat,
link |
we get eating-induced thermogenesis
link |
regardless of what we eat.
link |
Now, the eating-induced thermogenesis
link |
and increase in metabolism,
link |
which is an increase in temperature really,
link |
is probably greatest for amino acid-rich foods like meats,
link |
but also other types of foods.
link |
It's a minimal increase in body temperature
link |
compared to say cold exposure or exercise.
link |
Now, whether or not it's a quarter of a degree
link |
or half a degree or a degree,
link |
it really depends on the individual.
link |
And of course there are blood sugar effects.
link |
There are things like whether or not you are type one
link |
or type two diabetic,
link |
whether or not you're insulin resistant,
link |
whether or not like there's a kid
link |
who interns on the podcast here who's 17 years old
link |
and I'm convinced that he can eat anything
link |
and he just seems to like burn it up and he's growing.
link |
Every time, actually the other day,
link |
he walked into the other room and two days later,
link |
he walked out of the same room.
link |
He came out in between, of course.
link |
But, and I was like, he grew.
link |
He was like, you know, but he's at that stage
link |
where he's just growing.
link |
Food is going to affect a teenager very differently
link |
than it's going to affect a full grown person.
link |
So in general, starchy carbohydrates, white meats,
link |
such as turkey, some fish, increased tryptophan,
link |
therefore serotonin, therefore more lethargic states,
link |
Meat, nuts, and there are probably some plant-based foods
link |
that I'm not aware of and I apologize,
link |
I should read up on this,
link |
that also are high in tyrosine
link |
that can increase things like dopamine, norepinephrine,
link |
epinephrine, alertness.
link |
So you can vary these however you like.
link |
Most people I think are eating a variety of these things
link |
And there are other parameters of nutrition
link |
that are important too.
link |
Volume of food for the reasons I mentioned before,
link |
the volume of food in the gut,
link |
less food in the gut, whether or not it's empty
link |
or a small amount of food will tend to correlate
link |
Large volumes of food of any kind
link |
will tend to correlate and drive the calming response
link |
and that's by way of this nerve pathway called the vagus.
link |
We actually have sensory fibers in the gut
link |
that communicate to a little protrusion of neurons
link |
that sit right next to the juggler
link |
called the nodose ganglia, N-O-D-O-S-E.
link |
Unlike Costello, it's nodose, right now he's all those.
link |
Nodose actually means having many protrusions
link |
and it's like kind of a lumpy collection of neurons,
link |
a ganglia is just a collection of neurons
link |
and then it goes into the brain stem
link |
and then forward in the brain to the areas of the brain
link |
that are involved in production of various neuromodulators.
link |
So what we eat and the volume of food
link |
are both signaling to the brain,
link |
it's not just one or the other.
link |
And then there's also this eating induced thermogenesis
link |
and now you know from the discussion about temperature
link |
that if you're eating early in the day,
link |
you're tending to shift your rhythm earlier
link |
so that you'll want to wake up earlier the next day
link |
if you're eating very late in the day,
link |
even if you can fall asleep after that,
link |
there's a tendency for you to want to sleep
link |
later the next day.
link |
Now, this of course is all going to be constrained
link |
by when your kids need to eat
link |
and when your spouse needs to eat
link |
and when your friends need to eat
link |
or if you live alone or what other things you're doing.
link |
If you're like me and you kind of don't eat until noon
link |
then eat sometime around noon
link |
and then I'm terrible about meals,
link |
I just start eating the ingredients
link |
while I'm supposed to be cooking
link |
and then eventually they're all gone
link |
and I guess that's a meal, it varies.
link |
Some people are neurotically attached
link |
to a particular meal schedule, some people are not.
link |
I take my light exposure schedule far more seriously
link |
than I take my meal schedule,
link |
although in general, I try and eat healthy foods
link |
for the most part, croissants included.
link |
I was asked several times
link |
whether or not men and women or males and females
link |
differ in terms of these neurotransmitter phenotypes
link |
and the rhythms of sleep and temperature.
link |
We could probably devote a whole month
link |
and we probably will devote an entire month
link |
to what are called sex differences
link |
because those tend to be related to things
link |
we absolutely know like XX or XY chromosomes
link |
or XYY in some cases or double X chromosomes
link |
as opposed to gender, sex and karyotype as we call it,
link |
genetic makeup is crystal clear.
link |
There are things that correlate with one or the other
link |
but it's complicated and it's not something
link |
that's been explored in what I think is enough detail.
link |
Actually recently, I guess it was about five years ago,
link |
the National Institutes of Health made it a mandate
link |
that all studies use sex as a biological variable
link |
and actually explore both sexes of mice,
link |
both sexes of humans when doing any kind of study
link |
because there was a bias towards only using male animals
link |
or male subjects prior to that time.
link |
So a lot of data are now coming out
link |
revealing important sex differences
link |
that I think are going to have powerful impact
link |
on health practices, et cetera, response to drugs,
link |
response to different sleep schedules, et cetera.
link |
Perhaps the most salient and obvious one
link |
is that during pregnancy,
link |
females experience a whole range
link |
of endocrine and neural effects
link |
and we definitely will devote a month
link |
to pregnancy and childbirth and child rearing.
link |
And for that, I'd really like to bring in some experts.
link |
I've got terrific colleagues at Stanford and elsewhere
link |
that work on these things
link |
so that we can go into those in more depth.
link |
So I'm not blowing off those questions,
link |
I'm just kind of pushing them down the road a little bit
link |
where I can give you a more thorough answer.
link |
So as we finish up,
link |
I just want to offer you the opportunity
link |
to do an experiment.
link |
We've talked about a lot of variables
link |
that can impact sleep and wakefulness
link |
and in keeping with the theme of the podcast,
link |
we are going to continue
link |
to talk about sleep and wakefulness and tools for those
link |
and the science behind those tools as we go forward.
link |
But there are really just four simple parameters
link |
that you have control over
link |
that you can immediately start to record and take note of,
link |
just to see how you're doing with these things.
link |
With no judgment or perhaps no change
link |
to what you're actually doing.
link |
It might be interesting, just a suggestion,
link |
to write down for each day
link |
when you went outside to get sunlight
link |
and when you did that relative to waking.
link |
So you would write down,
link |
like the way I do this in my calendar is I'll write down
link |
that I don't get exact about it.
link |
I might say I woke up at 6.15
link |
and then I guess I'll put a W 6.15
link |
and then SL for sunlight.
link |
Now you sometimes get outside right away,
link |
other times I'm less good at that
link |
and I'll go out around, I don't know, let's say seven
link |
and for how long, maybe like 10, 15 minutes or so.
link |
And then I'll put a little check at roughly the times
link |
that I eat my so-called meals,
link |
although as I mentioned,
link |
sometimes my meals are a bunch of small checks
link |
that just kind of extend through the late hours of the day.
link |
Yours might be more confined to certain times.
link |
And then you might just take note of when you exercised,
link |
just put down an E for when you exercise,
link |
weight training or aerobic exercise.
link |
And you might note when you might've felt chilled or cold
link |
if you do, or you might've felt particularly hot
link |
or if you woke up in the middle of the night
link |
when you felt particularly hot.
link |
And then the last thing you might want to do
link |
is just write down if and when you did
link |
a non-sleep deep rest protocol, NSDR protocol,
link |
that could be meditation, that could be yoga nidra,
link |
that could be hypnosis,
link |
anything that you're using to deliberately
link |
teach your nervous system how to go from more alertness
link |
to more calmness in the waking state,
link |
even if it's waking up in the middle of the night
link |
and doing an NSDR protocol or in the afternoon
link |
or first thing in the morning to recover some sleep
link |
and ability to perform DPOs that you might've lost
link |
from a minimal or poor night's sleep.
link |
So you're going to write down when you woke up,
link |
when you viewed sunlight,
link |
that might be in the morning and the evening
link |
or just the morning,
link |
hopefully it's the morning and the evening,
link |
when you exercised, when you ate your meals
link |
and using a simple record keeping scheme
link |
like W for waking, SL for sunlight,
link |
maybe you come up with a system where it's a check
link |
or an X or something for exercise,
link |
this is not designed to make you neurotically attached
link |
to tracking all your behaviors and everything you do.
link |
I, for instance, don't track what I eat in particular,
link |
I kind of know what works for me
link |
and I just try and stay within that range.
link |
But by doing this, you can start to reveal
link |
some really interesting patterns,
link |
patterns that no answer that I could provide you
link |
about any existing tool or protocol could counter.
link |
It's really about taking the patterns of behaviors
link |
of waking and light viewing and eating and exercise
link |
and superimposing that on what you're learning
link |
in this podcast and elsewhere, of course,
link |
and what you already know, and trying to see
link |
where certain problems or pain points might be arising.
link |
Maybe you're eating really late in the day
link |
and you're waking up in the middle of the night really warm,
link |
well, now you would say, well, that could be due
link |
to kind of an increase in temperature
link |
that is extending my day.
link |
Or maybe you start to find that using cold exposure
link |
early in the day is great for you, but using it late,
link |
if it's too late in the day, that's not great.
link |
Or if you're into the sauna or it's even like some people,
link |
including myself, if I take a hot shower
link |
or sit in a hot tub or a sauna late at night,
link |
well, then I get a compensatory decrease
link |
in body temperature and I sleep great,
link |
provided I hydrate well enough,
link |
because that can be kind of a dehydrating thing
link |
to sit in hot conditions.
link |
But if I do the sauna early in the day,
link |
unless I exercise immediately afterward,
link |
then I tend to get the temperature drop,
link |
which makes sense because when you get in the sauna,
link |
you get vasodilatation, you throw off a lot of heat,
link |
and then you generally get a compensatory drop
link |
in temperature, if you do that early in the day,
link |
that's right about the time that that temperature
link |
is trying to entrain the circadian clocks of your body.
link |
That's what happens to me.
link |
Other people, it might be slightly different.
link |
And some people have more resilient systems than others.
link |
So I just encourage you to start becoming scientists
link |
of your own physiology, of your own brain and body,
link |
and seeing how the various tools
link |
that you may or may not be using
link |
are affecting your patterns of sleep,
link |
your patterns of attention and wakefulness.
link |
It's vitally important that if you do this,
link |
that you know that it's not about trying to get
link |
onto an extremely rigid schedule.
link |
It's really about trying to identify variables
link |
that are most powerful for you and that push you
link |
in the direction that you want to go
link |
and changing the variables that are pushing your body
link |
and your mind in the directions that you don't want to go.
link |
Self-experimentation is something
link |
that should be done slowly, carefully.
link |
You don't want to be reckless about this.
link |
And this is where I would say manipulating one
link |
or two variables at a time is really going to be best
link |
as opposed to changing a dozen things all at once
link |
to really identify what it is that's most powerful for you.
link |
As always, thank you so much for your questions.
link |
We are going to continue to answer questions.
link |
I certainly didn't get to all of them,
link |
but we tried to get to most all of the ones
link |
that were frequently asked.
link |
Episode four of the podcast,
link |
I'm going to get into shift work, jet lag,
link |
and age dependent changes in sleeping and wakefulness
link |
So for those of you with kids,
link |
for those of you that are kids,
link |
for those of you with older relatives
link |
or who might be older,
link |
meaning probably when you start to get into late 60s, 70s,
link |
and 80s is when there's some marked biological shifts
link |
in temperature regulation and things that relate to sleep.
link |
And for those of you that travel,
link |
we're going to talk about jet lag.
link |
The shift work discussion might seem only relevant
link |
to those that work nights, but actually that's not the case.
link |
Most people, because of the way they're interacting
link |
with devices, are actually in a form of shift work now,
link |
where the days are certainly not nine to five,
link |
so-called banker's hours,
link |
and then the lights are out at nine
link |
and they're asleep until 5 a.m.
link |
Some people have that schedule, most people do not.
link |
So episode four, we will go deeply into shift work,
link |
jet lag, age dependent changes in sleep alertness
link |
and cognition, and I will touch back
link |
on a few of your questions,
link |
but don't think that if your question wasn't answered
link |
during these office hours that we won't get to it.
link |
I absolutely will at some point.
link |
In addition to that, several of you have graciously asked
link |
how you can help support the podcast,
link |
and we very much appreciate that.
link |
You can support the podcast by liking it on YouTube,
link |
by subscribing on YouTube,
link |
by recommending the YouTube videos to others,
link |
as well as subscribing and downloading the podcast on Apple,
link |
where you can also leave a review, and on Spotify,
link |
or all three, if you like.
link |
You can also help us by supporting our sponsors,
link |
so check out some of the sponsor links
link |
that were described at the beginning of the episode.
link |
And in general, recommending the podcast
link |
to people that you know and that you think would benefit
link |
from the information would be terrific.
link |
As always, I will be continuing to post on Instagram.
link |
You can expect another podcast episode out next Monday
link |
about the topics that we've been discussing this month.
link |
And above all, thank you for your interest in science.
link |
We'll see you next time.