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- Welcome to the Huberman Lab Podcast
where we discuss science
and science-based tools for everyday life.
(energetic music)
I'm Andrew Huberman
and I'm a professor of
neurobiology and ophthalmology
at Stanford School of Medicine.
Today's podcast episode
is all about sleep,
and we're also going to talk about
the mirror image of sleep,
which is wakefulness.
Now, these two phases of our life,
sleep and wakefulness,
govern everything about our
mental and physical health,
and we're not just gonna talk about
what's useful about sleep,
we're also gonna talk about
how to get better at sleeping,
and that will include how to
get better at falling asleep,
timing your sleep, and
accessing better sleep quality.
In doing so, we're also gonna discuss
how to get more focused
and alert in wakefulness,
so because sleep and
wakefulness are related,
we really can't have a
conversation about one
without the other.
Now, in keeping with this theme,
you may catch a few
snores in the background.
Unlike me, my bulldog, Costello,
can fall asleep anywhere, anytime,
and he happens to be sleeping
over there in the corner,
so if you hear snoring,
that's what that's about.
As always, I wanna just
mention that this podcast
is part of my effort to bring
zero-cost-to-consumer public education
about science and science-related tools,
it is unrelated to my
teaching and research roles
at Stanford School of Medicine.
Today's podcast is brought
to us by Helix mattresses,
having the proper sleep environment,
both the environment you're sleeping in
and the object you're sleeping on,
is critically important to
getting a good night's sleep.
Helix mattresses are a
little different than most
because they're matched to
your specific sleep needs,
as well as whether or not
you tend to run hot or cold
as you sleep through the night,
what position you sleep in, and so forth,
so if you go to their website,
they have a quiz that you can take
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I've always had a lot of trouble sleeping,
I'm one of these people
that can fall asleep easily,
but then I wake up
and I have a hard time
getting back to sleep,
and once I switched to a Helix mattress
that was precisely
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I found I could sleep through the night,
which has made a tremendous
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If you wanna try Helix mattresses,
you can go to helixsleep.com/huberman,
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and of course, having the proper pillows
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having the proper mattress.
Today's podcast is also
brought to us by Headspace,
Headspace is a meditation app
that teaches you how to meditate.
It's fair to say that now there's
a ton of research out there
in peer-reviewed journals
supporting the fact that
mindfulness meditation
can support mental and physical health,
but many people find it hard to meditate,
in fact, I'm one of these people.
I started meditating in my teens,
but then I would drop
it every few weeks or so
and then I'd get back to it
maybe the following week or every year,
I just was not very regular
about my meditation practice,
and then a few years ago I
was flying a lot for work
and I was on JetBlue flights,
and they have Headspace as
part of the choice of things
that you can watch on the TV screen,
and as I started
meditating more regularly,
what I found is my sleep was better,
I would arrive feeling more rested,
it was just a tremendous effects
on my work performance and
other aspects of my life.
If you wanna try Headspace,
you can go to headspace.com/specialoffer,
if you do that, you'll get one month
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meditations for free,
that's the best offer right now,
so if interested, go to
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So let's talk about sleep,
sleep is this incredible
period of our lives
where we are not conscious.
We might dream, we might
twitch, we might even wake up,
but in sleep, we are only in relation
to things that are happening
within our brain and body.
Outside sensory experience, in most cases,
can't really impact us,
and yet, sleep is this tremendously
important period of life
because it resets our ability
to be focused, alert,
and emotionally stable
in the wakeful period,
so we can't really talk
about wakefulness, focus,
motivation, mood, wellbeing
without thinking about sleep,
and that's why we're
devoting this entire month
to the discussion about sleep.
Now, we also can't talk about
sleep and think about sleep
without thinking about wakefulness
because it turns out that
the period that we call sleep
and the period we call wakefulness
are tethered to one another.
What we do in the waking state
determines when we fall asleep,
how quickly we fall asleep,
whether or not we stay asleep,
and how we feel when we
wake up the next day,
and today, we're going to talk mostly
about how to get better at sleeping,
and the reason for starting
the conversation that way
as opposed to just diving into
a lot of biology about sleep,
is because first of all,
there's a lot of information
out there already
about the biology of sleep.
We're gonna touch on a little bit of this,
things like stages of
sleep and sleep spindles,
melatonin, and dreaming,
but I think that by now,
most people are aware
that getting a really good night's sleep
on a consistent basis
is critically important,
but most people don't know how to do that.
In fact, I'm guessing that
very few of you out there
are consistently getting
seven to nine hours
of really terrific sleep,
waking up feeling rested
and like you're ready to attack the day,
and being able to go through the day
feeling focused and alert
without dips in energy or focus,
so if you're like most
people, which includes me,
you have some challenges with sleep
at least every third or fifth night or so
and maybe even more often,
so we're really gonna go tool-heavy today
and talk about tools that
can help you fall asleep,
sleep better, and emerge from
sleep feeling more rested,
and we're gonna do that by
grounding our discussion of tools
in peer-reviewed studies,
mostly from the last 10 years,
although some even more recent than that,
and we're gonna start by
discussing what is sleep
and what governs the timing
of the onset of sleep,
in other words, what makes you get sleepy
at a particular time of day.
So what determines how well we sleep
and the quality of our wakeful state?
Turns out that's governed by two forces,
the first force is a chemical force,
it's called adenosine.
Adenosine is a molecule in
our nervous system and body
that builds up the longer we are awake,
so if you've just slept for 8, or 9,
or 10 really deep, restful hours,
adenosine is gonna be very
low in your brain and body.
If, however, you've been awake
for 10, 15, or more hours,
adenosine levels are
going to be much higher.
Adenosine creates a sort of
sleep drive or a sleep hunger,
and actually, hunger is
the appropriate word here
because for most of what
we're gonna discuss today,
we can think of it in an
analogous way to nutrition.
Your nutrition and how well you feel
after you eat certain foods,
your overall level of fitness
and your cellular health
and your heart health
isn't governed by any one food item
that you might eat or not eat,
it's governed by a number
of different factors,
how often you eat, how much you eat,
which items you eat, et cetera,
and what works best for you.
In the same way, your
sleep and your wakefulness
are the product of kind of the average
of a number of different behaviors,
how long you've been awake is a key one
because of this molecule, adenosine.
So the reason you get sleepy
when you've been up for a while
is because adenosine
is creeping up steadily
the longer you've been awake,
and a good way to remember
this and think about adenosine
is to think about caffeine.
Caffeine, for most people,
except a very small percentage of people,
wakes them up, it makes
them feel more alert,
in fact, some people are
so sensitive to caffeine
that they feel jittery if they drink it
even in small amounts,
other people can drink
large amounts of caffeine
and not feel jittery at all.
Caffeine acts as an adenosine antagonist,
what that means is that
when you ingest caffeine,
whether or not it's coffee or soda or tea,
or in any other form,
it binds to the adenosine receptor,
it sort of parks there just like a car
would park in a given parking slot,
and therefore, adenosine
can't park in that slot.
Now, when caffeine parks in
the adenosine receptor slot,
nothing really happens
downstream of that receptor,
the receptor can't engage
the normal cellular
functions of making that cell
and you feel sleepy.
So the reason caffeine wakes you up
is because it blocks
the sleepiness receptor,
it blocks the sleepy signal,
and this is why when
that caffeine wears off,
adenosine will bind to that receptor,
sometimes with even greater,
what we call affinity,
and you feel the crash,
you feel especially tired.
Now, I'm not here to demonize
caffeine, I love caffeine,
and I drink it in the morning
and I drink it in the afternoon,
but I'm one of these people
that, either because of my tolerance
or because of some genetic variations
that exist among people
in terms of their adenosine receptors,
I can drink caffeine
as late as 4:00 or 5:00
p.m. in the evening
and still fall asleep just fine.
Some people can't have any caffeine at all
or can't have any caffeine past 11:00 a.m.
or else their sleep is totally disrupted.
All of this has to do
with the relationship
between adenosine and
these adenosine receptors,
genetic variation,
things that are very hard to
find out except experimentally,
meaning each of you needs to decide
and figure out for yourselves
whether or not you can tolerate caffeine
and at what times of day
you can tolerate caffeine
in order to still fall asleep
easily and get good sleep,
so rather than demonize caffeine,
or say that everyone can
drink caffeine until late,
you need to figure out
what's right for you.
Caffeine has a lot of health benefits,
it also, for some people,
can be problematic for health,
it can raise blood pressure, et cetera,
caffeine increases this molecule
that's a neuromodulator
that we call dopamine,
we discussed this in episode one,
which tends to make us
feel good, motivated,
and give us energy
because, as you may have
learned in episode one,
dopamine is related to
another neuromodulator
called epinephrine, which gives us energy,
in fact, epinephrine
is made from dopamine.
So let's just take a step back
and think about what we're talking about
when we're talking about sleepiness,
sleepiness is driven by
increases in adenosine
that happen naturally,
caffeine prevents the adenosine
from having its action of making us sleepy
by blocking that receptor,
so it gives us energy and it
increases our dopamine levels,
but some people can't
tolerate caffeine very well,
other people can tolerate it just fine,
so you need to determine
that experimentally.
All the data say there's
tremendous variation,
and right now, the only
way that I'm aware of
for you to decide whether or not
caffeine is a good or a bad thing for you,
and whether or not you should ingest it
at a given time of day or at all
is really to figure that out on your own,
in fact, there's a small subset of people
that can drink caffeine until very late
and they have no trouble falling asleep
because they actually have a mutant form
of the adenosine receptor,
so in keeping with the theme
of science and science-related tools,
this is one of those cases
where I can't give you a
one-size-fits-all prescription
except to say you need to
experiment with caffeine
in a way that's safe for you
and explore that and figure
out what works for you,
and then stick with that.
Okay, so adenosine is
driving this sleep hunger,
when adenosine is low,
it's like we're well-fed,
we're not very hungry,
and when adenosine is high,
it's like we're fasted for a long time
and we tend to be very hungry,
so that when adenosine is high,
we really wanna fall asleep.
If you want, I'm not suggesting
you do this experiment,
but you can do it,
you can stay up for four more hours
than you're used to staying up
and you'll find that
you're very, very sleepy.
That's because adenosine is building up
at levels higher and higher
because you've been awake
for those extra four hours.
However, if you've ever
pulled an all-nighter,
you'll notice something interesting,
as morning rolls around,
you'll suddenly feel an increase
in your energy and alertness again,
even though adenosine has been building up
for the entire night.
Now, why is that?
The reason that is is because
there's a second force
which is governing when you
sleep and when you're awake,
and that force is a
so-called circadian force,
circadian means about a
day or about 24 hours,
and inside all of us is a clock
that exists in your brain and my brain,
and the brain of every
animal that we're aware of,
that determines when we want to be sleepy
and when we want to be awake.
Just think about it,
we don't go through the day
wanting to fall asleep every 30 minutes
and then feeling like we're wide awake,
our sleep and our period of sleepiness
tends to be condensed into one block,
typically one 6- to 10-hour block,
although there's also variation
in terms of how much people want to sleep,
and we're going to discuss
how you can diagnose
your absolute sleep need
as well as how to recover
sleep that you've lost.
That block of sleep
and when it falls within
each 24-hour cycle
is governed by a number
of different things,
but the most powerful thing
that's governing when
you want to be asleep
and when you want to be awake is light,
and in particular, it's
governed by sunlight,
and I can't emphasize enough
how important and how
actionable this relationship is
between light and when you want to sleep.
It's quite simple on the face of it
and it's quite simple to resolve,
but people tend to make a big mess
of this whole circadian
literature, frankly,
so let's just break it
down from the standpoint
of what's going on in your brain and body
as you go through one 24-hour day.
Let's start with waking,
so regardless of how
well you slept at night
or whether or not you were up all night,
most people tend to wake up
sometime around when the sun rises,
maybe not right at sunrise,
but within an hour or two
or maybe three of sunrise.
Now, I realize there
are night-shift workers
and there are people traveling
and experiencing jet lag
where this is not going to be the case,
we are gonna deal with
jet lag and shift work
at the end of this podcast,
but for most people, we tend to wake up
about the time that the
sun is rising or so,
and as we do that,
adenosine levels tend to
be low if we've been asleep
for reasons that you now understand,
and our system generates
an internal signal
that is in the form of a hormone.
Now, I've talked a lot about
neuromodulators and neurotransmitters,
I haven't talked a lot about
hormones yet on this podcast.
The definition of a hormone
is it's a substance,
a chemical that's released
from one organ in your body
that goes and acts on other
organs elsewhere in your body,
including your nervous system.
When you wake up in the morning,
you wake up because a particular
hormone called cortisol
is released from your adrenal glands,
your adrenal glands sit
right above your kidneys,
and there's a little pulse of cortisol.
There's also a pulse of some,
and when I say a pulse,
I just mean the release of a little bit,
there's also a pulse of
epinephrine, which is adrenaline,
from your adrenals and also in your brain,
and you feel awake.
Now, that pulse of cortisol
and adrenaline and epinephrine
might come from your alarm clock,
it might come from you
naturally waking up,
but it tends to alert your
whole system in your body
that it's time to
increase your heart rate,
it's time to start tensing your muscles,
it's time to start moving about.
It's very important
that that cortisol pulse
come early in the day,
or at least, early in your
period of wakefulness,
I say that because some people
are waking up at 8:00 p.m.
and are sleeping all day,
but it's very important
that that pulse of cortisol
occur early in the day and
that it happens all at once,
it sort of sets a rising tide
of cortisol in your system.
Now, many of you have
probably heard about cortisol
in relation to stress,
and indeed, as we go through
our day and our life,
different stressors, different
events happen in our life
that make us feel more alert.
Some of the more stressful ones
might be looking at your credit card bill
and seeing what seems to
be a fraudulent charge,
or looking at your phone
and suddenly seeing a text that something
you thought was gonna
happen at a particular time
is not gonna happen,
or you're running late,
those will tend to increase norepinephrine
and epinephrine and
adrenaline in your system,
and if they're severe enough,
you'll start getting
some pulses of cortisol
released from your adrenals
throughout the day,
but there's this normal,
healthy rising tide of cortisol
that happens early in the day,
and I say healthy because it wakes you up,
it makes you feel alert,
and it makes you feel able
to move and wanting to move
and to go about your day
for work, for exercise,
for school, for social
relations, et cetera.
So when you wake up in the morning
is when that cortisol pulse takes off,
and something else important happens,
a timer is set in your body
and in your nervous system
that dictates when a different
hormone called melatonin,
which makes you sleepy,
will be secreted from a
particular brain region,
so let's talk about that.
When you wake up in the morning
and you experience that rise in cortisol,
there's a timer that starts going,
and these are cellular timers
and they're dictated by the relation
between different organs in your body,
that says to your brain and body
that in about 12 to 14 hours,
a different hormone, this
hormone we're calling melatonin,
will be released from your pineal gland.
So there's two mechanisms here,
a wakefulness signal
and a sleepiness signal,
and the wakefulness signal
triggers the onset of the timer
for the sleepiness signal.
Now, that sleepiness signal
that we call melatonin
that's released from the pineal
comes only from the pineal.
Unless you're taking exogenous melatonin,
you're supplementing with melatonin,
the only source of melatonin in your body
is going to be this pineal gland,
so let's talk about the
pineal gland for a second.
The pineal gland is a gland
that sits kind of in the
little structure near,
for the aficionados out there,
it's kind of near the fourth ventricle,
it's about the size of a pea,
Descartes, the philosopher,
said that the pineal was
the seat of the soul,
he said that because it's
one of the few structures
in the human brain
that there's only one of them,
you know, most structures,
there's one on either side of the brain,
so-called bihemispheric,
but the pineal, there's only one.
I don't know anything about souls, really,
certainly not the science of souls,
but I think it's very unlikely
that the pineal is the seat of the soul,
but it is a very interesting organ
because it's the only organ in our body
that releases melatonin,
and that melatonin makes us
sleepy and lets us fall asleep.
Now, I'm guessing that many
of you are probably asking,
"Should I take melatonin?"
My personal bias on this is,
except in rare cases, no,
for the following reason,
melatonin has a second function,
which is that melatonin
also suppresses the onset of puberty.
In kids, and especially in babies,
melatonin isn't just
released in the evening
12 to 16 hours after we wake,
melatonin is released
chronically, or tonically,
throughout the day and night,
and that chronic or tonic
release of melatonin
is known to suppress some
of the other hormones
in other regions of the brain
that trigger the onset of puberty.
Now, if you or your child
has been taking melatonin,
don't freak out,
as always, any kind of supplement
or anything that you're going
to take or think about taking,
you really need to
consult with your doctor,
I've said this many times on this podcast
and it's in the show notes, et cetera,
but before you remove anything
or add anything to what
you're already doing,
please do consult with a
healthcare professional.
However, melatonin is known
to suppress the onset of puberty,
so much so that regular, cyclic,
cycled periods of melatonin
release from the pineal
really correlate with the onset of puberty
and early adulthood,
meaning as we start secreting
melatonin only at night,
that's also when we tend to
transition out of puberty.
Now, there are a lot of
things that correlate
in our nervous system,
so that doesn't necessarily
mean it controls it,
but in this case we know,
based on lots of data,
endocrinology and so forth,
that melatonin suppresses
the onset of puberty,
so supplementing melatonin
could be problematic
for that reason,
but if you've already
gone through puberty,
it could also have some impact
on other hormone systems in your body,
so that's why I personally
don't like to use
melatonin to fall asleep.
There's another reason,
which is that melatonin
will help you fall asleep
but it won't help you stay asleep,
and many people who take melatonin
find that they wake up
three to five hours later
unable to fall back asleep.
Part of the reason for that might be
that melatonin purchased at,
you can buy it over the counter
in most areas of the world
even though it's a hormone,
which is a little unusual,
you can't just go into a
pharmacy, at least in the US,
and buy testosterone or
cortisol or estrogen,
you need a prescription,
but you can go buy melatonin
for whatever reason,
I don't know the reasons
for that legality,
but it's been shown many times,
and now I'm borrowing from some items
that were in Matt Walker's
book, "Why We Sleep,"
where he stated there is evidence
that, in commercially available melatonin,
the amount of melatonin has
been tested for various brands,
it can range anywhere from being
15% of what's listed on the bottle,
okay, so if they list
this as 100 milligrams,
it would be a tremendously high dose,
it turns out it's only 15 milligrams
in that particular pill or capsule,
or up to 400 times more than
what's listed on the bottle,
so it's completely unregulated,
and so for those of you taking melatonin,
I will discuss at the end of the podcast
some other potential alternatives
that are probably safer
and don't have these issues.
So should you take melatonin?
My personal bias is no,
but for many people, they
find that it does help them,
and so if you do find it helps you,
then just consider what I'm saying
in light of the other
practices that you're doing
and talk to your healthcare professional.
Okay, so the rhythm of
cortisol and melatonin
is what we call endogenous,
it's happening in us all the time
without any external input,
in fact, if we were in complete darkness,
living in a cave with no
artificial lights whatsoever,
or we were in complete brightness
where we never experienced any darkness,
these rhythms of cortisol
and melatonin would continue,
you would have a bump in
cortisol, or a pulse in cortisol,
that would drop off with time,
and then melatonin would come
up about 12 to 14 hours later,
but these endogenous systems of our body,
which are both hormonal and neural,
were set so that external things
could govern when they happen.
Now, this takes us back to
episode one of the podcast
that if you haven't listened to already,
you might wanna listen to,
where we talked about sensation
and perception and all that,
I'm not gonna review it again here,
but there's one particular sensory event,
one particular influence
on your nervous system
that determines when that cortisol
is going to start to rise,
so if you were in complete darkness,
it would happen once per 24-hour cycle,
but it would be somewhat
later and later each day,
whereas under normal circumstances,
what happens is you wake up,
and what happens when you wake up?
You open your eyes.
When your open your eyes,
light comes into your eyes.
Now, the way this system works
is that you have a particular
set of neurons in your eye,
they're called retinal ganglion cells,
you don't have to remember
that if you don't want to,
but these retinal ganglion
cells are brain neurons,
again, the retina is just
the one piece of your brain,
actually, two pieces because
most of you have two retinas,
that resides outside the skull, per se.
When light comes into the eye,
there's a particular group
of retinal ganglion cells,
or type of retinal ganglion cells,
that perceives a particular type of light
and communicates that to this clock
that resides right above
the roof of your mouth
called the suprachiasmatic nucleus, okay?
So I know this can get
a little complicated,
but these retinal ganglion cells,
when you open your eyes, light comes in,
and an electrical signal is
sent to this central clock
we call the suprachiasmatic nucleus,
and the suprachiasmatic
nucleus has connections
with essentially every cell
and organ of your body.
Now, it's vitally important
that we get light communicated
to this central clock
in order to time the cortisol
and melatonin properly,
and when I say properly, I
can say that with confidence
because we know based on a lot of evidence
that if you don't get
your cortisol and melatonin rhythms right,
there are tremendously
broad and bad effects
on cardiovascular health,
dementia, metabolic effects,
learning, depression, dementia,
in fact, there're so many negative effects
associated with getting this wrong
that I don't wanna get
into it in too much detail,
in fact, I feel like we've been bombarded
with all this information about
how we're not sleeping well,
we're not sleeping at the right times,
we're not sleeping enough,
to the point where people
now have sleep anxiety,
if they can't sleep well for a night,
they're feeling overwhelmed by that
and it's sort of now they're stressed
about not being able to sleep
which is making it harder
to sleep, et cetera.
I really wanna focus on what we can do
to anchor these systems properly,
so let's think about what
happens when we do this correctly
and how to do it correctly.
When we wake up, our eyes open,
now, if we're in a dark room,
there isn't enough light to
trigger the correct timing
of this cortisol-melatonin
thing, these rhythms.
You might say, "Well, why
won't any light do it?"
Well, it turns out that
these neurons in our eye
that set the circadian clock
and then allow our circadian
clock to set all the clocks
of all the cells and organs
and tissues of our body
responds best to a
particular quality of light
and amount of light,
and those are the qualities
of light and amount of light
that come from sunlight,
so these neurons, what
they're really looking for,
although they don't have
a mind of their own,
is the sun at what we
call low solar angle,
the eye and the nervous system
don't know anything about
sunrises or sunsets,
it only knows the quality of light
that comes in when the
sun is low in the sky,
the system evolved so that
when the sun is low in the sky,
there's a particular contrast
between yellows and blues
that triggers the
activation of these cells,
so if you wake up and
you look at your phone
or your computer,
or you flip on a bunch
of artificial lights,
will these cells be activated?
And the answer is, sort of,
they'll be activated but
not in the optimal way.
What you want to do is
get sunlight in your eyes
as close to waking as possible.
Now, I wanna be really clear about this
because I've talked about it
on other podcasts when I was a guest
and I talked about it
on my Instagram feed,
and there seemed to be the same questions
coming up again and again,
these neurons don't know sunlight, per se,
they don't know sunrise or
sunset, for that matter,
they don't know artificial
light from sunlight,
what they respond best to,
however, is the quality
and amount of light
that comes in when the
sun is low in the sky,
that means that if you can
watch the sunrise, great,
that's perfect for triggering
activation of these cells,
however, if you wake up a
few hours after the sunrise,
which I tend to most days, personally,
you still wanna get
outside and view sunlight,
you don't need the sunlight
beaming you directly in the eyes,
there's a lot of photons, light energy,
that's scattered from
sunlight at this time,
but the key is to get that light energy,
from sunlight, ideally, into your eyes.
Now, I know many of
you are already asking,
"Well, I live in Scandinavia,"
or, "I can't get sunlight,
"there's buildings around me," et cetera,
we will get to all of that,
but it's critically important
that you get outside to get this light.
I had a discussion with
a colleague of mine,
Dr. Jamie Zeitzer, who's in
the Department of Psychiatry
and Behavioral Sciences at Stanford,
a world expert in this,
and he tells me that it's
50 times less effective
to view this sunlight through a window,
through a car windshield,
or through the side window of a car
than it is to just get
outside with no sunglasses
and view light early in the day.
Now, if you can't see the sunrise,
like I said, you can see this
within an hour or two of sunrise,
but it has to be low solar angle,
once the sun is overhead,
the quality of light shifts
so that you miss this opportunity
to time the cortisol pulse,
and that turns out to
be a bad thing to do,
you really wanna time that
cortisol pulse properly
because, we'll get into this
a little bit more later,
but a late-shifted cortisol pulse,
in particular, a 9:00 p.m. or
8:00 p.m. increase in cortisol
is one of the consequences,
and maybe one of the causes,
of a lot of anxiety
disorders and depression,
so it's kind of a chicken-egg thing,
we don't know whether or
not it's correlated with,
it's the cause, or the effect,
but it's a signature of
depression and anxiety disorder.
Bringing that cortisol pulse
earlier in your wakeful period,
earlier in your day,
has positive benefits
ranging from blood pressure
to mental health, et cetera,
not gonna list them all off
because there's just so many of them,
but many, many positive things happen
when you are getting the
cortisol early in the day
far away from your melatonin pulse.
Okay, so how long should you be outside?
Well, this is gonna vary tremendously
because some people live in environments
where it's very bright,
so let's say it's Colorado
in the middle of winter,
there's a snowfield,
there's no cloud cover,
and you walk outside,
there's going to be so
much photon light energy
arriving on your retina
that it probably only
takes 30 to 60 seconds
to trigger the central clock
and set your cortisol and
melatonin rhythms properly
and get everything lined up nicely,
whereas if you're in Scandinavia
in the depths of winter
and you wake up at 5:00 a.m.
and the sun is just barely
creeping across the horizon
and then goes back down
again a few hours later,
you probably are not
getting enough sunlight
in order to set these rhythms,
so many people find that they need to use
sunlight simulators in the
form of particular lights
that were designed to simulate sunlight,
however, and I'm not out to attack
the companies that produce those,
there's another solution to that,
you can simply go outside for longer,
even if there's a lot
of dense cloud cover,
you're probably getting anywhere
from 10,000 to 50,000 lux,
L-U-X, which is just a
measure of light energy,
and that should be sufficient
to set the circadian clock.
You could say, "Well, the
lights in my house or my phone
"are really, really bright, right?
"Everyone's telling us to
stay off our phones at night
"because they're really bright,"
but guess what, it turns
out that early in the day,
your retina is not very sensitive,
which means you need a lot of photons,
ideally coming from sunlight,
to set these clock mechanisms,
so looking at your phone or
artificial lights is fine
if you wake up before sunrise,
but it's not going to work to
set these clock mechanisms,
and this is supported by
dozens, if not hundreds,
of quality peer-reviewed studies,
so you wanna use sunlight,
if you can't see sunlight
because of your environment,
then you are going to have
to opt for artificial light,
and in that case, you're going
to want an artificial light
that either simulates sunlight
or has a lot of blue light.
Now, without going off course here,
you might be saying,
"Wait, I've heard blue
light is bad for me."
Actually, blue light is
great for this mechanism
during the day,
we can talk about blue
light and blue blockers,
but you really want a lot
of blue and yellow light
arriving on the retina early in the day.
Let me be clear about something,
you never ever want to look at any light,
sunlight or artificial light,
that is painful to look at.
If you find that your eyes are watering
or you're having challenges maintaining,
you know, looking at
this thing for a while
because it's painful,
that light is too bright
and you do not wanna damage your retina,
so you don't wanna gaze at
the sun refusing to blink
and burn your retina, that's
actually possible to do,
you don't wanna do that.
You have a proper blink reflex
installed in you since birth,
and if you feel like
something's too bright
and you need to blink,
it means you need to blink,
that it's too much light,
so please don't beam your
eyes with really bright light,
but blue light,
in particular, blue light and yellow light
coming from sunlight is ideal,
if you're going to get
it from artificial light
because you can't get enough sunlight,
well, then, artificial lights
that are rich in blue, blue wavelengths,
are going to be ideal for
setting this mechanism.
A lot of people will say, "Oh, I should be
"wearing blue blockers
throughout the day."
No, that's the exact wrong thing,
if you're going to use blue blockers,
we can talk about that,
that should be reserved
for late in the evening
because light suppresses melatonin.
I've been asked many times
before about this pineal gland
and there are a lot of ancient practices
that map to some of the
things that I'm saying,
and people will always say,
"Oh, I heard that sunlight
"is great for the pineal."
Well, perhaps, but we have
to careful about that phrase,
sunlight inhibits the pineal,
it prevents it from releasing melatonin,
darkness allows the pineal
to release melatonin,
so the pineal is not the gland
or the organ of sunlight,
it is the gland of darkness,
in fact, melatonin can be
thought of as a sleepiness signal
that's correlated with darkness,
so get up each morning,
try and get outside,
I know that can be challenging for people,
but anywhere from 2 to 10
minutes of sunlight exposure
is going to work well for most people,
and you wanna do this on a regular basis
and you don't have to do
it exactly at sunrise,
I realize I'm repeating myself,
but somehow, despite
barking at people about this
for a couple years now,
I keep getting the same questions,
and somehow, it hasn't been sinking in,
which could be related to
some circadian disorder,
I'm just kidding, if it's not sinking in,
it's probably that I'm not being effective
in communicating the information,
but get that bright light
early in the day from sunlight,
and if you can't get it from sunlight,
get it from artificial light.
What kinds of artificial lights will work?
Well, there are these sunrise simulators,
but the ring lights that
people use for selfies
and this sort of thing,
for posting on Instagram,
those generate a lot of blue light.
If wanna get experimental about this,
there's a free app, I have
no relationship to the app,
but it's a great app called Light Meter
that you can use your phone
and you can measure the
amount of photon energy
in your environment,
and it's kind of a fun experiment to do,
you can go outside in the morning
and you'll see that
there's 10,000, 20,000 lux,
even though it might
seem like it's kinda dim
or there's tree cover or cloud cover,
you go inside and you
shine an artificial light
at your phone,
press the button on Light Meter
and you'll find that it's
only 500 or 1,000 lux,
and you realize that even
though it seems really bright,
the artificial light is very condensed,
whereas the outside light is
scattered in the atmosphere,
and so you can think that
you're not getting much sunlight
but you're actually
getting much more outside,
so get outside, get that
sunlight early in the day,
and try and do it on a consistent basis.
If you can't do it every day
or you sleep through this
period of the early day,
low solar angle,
don't worry about it,
these systems in the body,
these hormone systems and
neurotransmitter systems
that make you awake at
certain periods of the day
and sleepy at other times
are operating by averaging
when you view the brightest light.
Now, that can immediately tell us
that what most people
are doing is terrible,
they're waking up and they're
looking at their phone,
which isn't triggering activation
of these cells in the eye
and the central circadian clock,
then a few hours later,
they might get in their car
with sunglasses and drive.
Now, a note about sunglasses
and prescription lenses,
absolutely never, ever,
ever compromise safety
for the sorts of things I'm talking about,
so if you need to wear
sunglasses for safety reasons,
wear them,
absolutely, if you wear
prescription lenses or contacts,
wear them, they won't filter
out the wavelengths of light
that are necessary for
setting these central clocks,
so safety first, of course,
if you have a retinal
degenerative disorder,
retinitis pigmentosa, macular
degeneration, or glaucoma,
or those run in your family,
you want to avoid excessively
bright light all the time,
you wanna be very cautious about that,
you're going to wanna
get your light exposure
through seeing dimmer
light, including sunlight,
but for longer periods of time, perhaps.
You might immediately ask,
"What about low-vision or blind people,
"how do they set these central clocks?"
Well, turns out that
low-vision and blind people,
most of them, provided
they still have eyes,
that the eyes weren't removed
because of a burn or a tumor
or something like that,
still maintain these neurons
that set the circadian clock,
which brings me to a
really important point,
it's not about seeing
and perceiving the sun,
this is a subconscious mechanism
by which these neurons,
which are called
melanopsin ganglion cells,
these neurons set your central clocks
by getting activated by the
particular wavelengths of light
that are present in the atmosphere,
even coming through cloud cover,
and you don't need to
see or perceive the sun
in order to get this mechanism to start.
Now, it's such a vitally
important mechanism
because it dictates how well
and what time you will want to
fall asleep later in the day,
so for those of you that are night owls
and you insist that you're a night owl
and you have the genetic polymorphism
that makes you a night owl,
you may very well have
that genetic polymorphism,
those genes that make
you want to stay up late
and wake up late,
but chances are, about half of you
that think that you're night owls
are just not getting enough
sunlight early in the day.
So viewing light early in
the day, ideally sunlight,
is key for establishing
healthy sleep-wake rhythms
and for allowing you to
fall asleep easily at night.
Now, it's not gonna make sure
that all that happens every single time,
but it is the foundation of proper sleep
and what we call circadian health,
it governs metabolism
and so many other things
that are supposed to exist
on a regular 24-hour cycle.
Some of you, many of you, might be asking,
"What else can help set this rhythm?"
Well, it turns out that light
is what we call the primary
zeitgeber, the time giver,
but other things can help
establish this rhythm of cortisol
followed by melatonin 12
to 16 hours later as well.
The other things besides light
are timing of food intake,
timing of exercise,
as well as various drugs or
chemicals that one might ingest,
not illegal drugs,
although those will impact
circadian mechanisms as well,
but the reason we focus
so heavily on light
is that light is the main
way that this central clock,
the suprachiasmatic nucleus,
was supposed to be set,
and we know that because
it's the only direct input
to the clock.
These neurons in the eye that
are also part of the brain
that we call melanopsin ganglion cells
that, not so incidentally, were discovered
by my friend and colleague David
Berson at Brown University,
and others, Samer Hattar,
King-Wai Yau, et cetera,
worked out the mechanisms,
the molecular mechanisms,
but it was really David Berson
that discovered these
incredibly fascinating,
you know, these are cells that
aren't important for sight
like pattern vision,
but are for setting our clocks,
David's really credited
with making that discovery.
Those cells are the main way
and the only direct way to set the clock,
in fact, it's fair to say
that light viewed by
these melanopsin cells,
in particular, sunlight,
is 1,000 to 10,000 times more effective
than, say, getting up in
darkness and just exercising.
That doesn't mean that you shouldn't
exercise early in the day in darkness
if that's what you like to do,
it will have somewhat an effect
on raising your wakefulness
early in the day
and setting these rhythms,
and this is because of
some other pathways,
for the aficionados out there
who wanna know more neuroscience,
here's how it goes, you've got this clock
above the roof of your mouth
that churns out this 24-hour rhythm
and it's communicated
to all the other organs
and tissues of your body,
but there's another structure,
it has a cool name, it's called
the intergeniculate leaflet,
which sits a few millimeters
away in the brain,
and it's involved in
regulating the clock output
through what's called non-photic,
non-light-type influences
like exercise and feeding, et cetera.
So if you are not feeling
awake during the day
and you're having trouble sleeping,
get the sunlight exposure
that we just talked about,
but in addition to that,
if you wanna become an
early riser, for instance,
and you wanna feel more awake
during the early part of the day,
by getting that light exposure
and exercising early in the day,
you will, after two or three days,
you will naturally start to
wake up earlier in the day,
and that's because these
clock mechanisms have shifted,
it's like setting the clock earlier
as opposed to delaying the clock,
and that takes us to a
somewhat complicated,
but very important, aspect to all this,
which is, what sets the
clock and keeps it anchored?
The main thing is that bright
light early in the day,
the other thing is sunset,
when the sun is also at low solar angle,
low, close to the horizon,
by viewing sunlight at that
time of day in the evening,
or afternoon, depending
on what time of year it is
and where you are in the world,
these melanopsin cells,
these neurons in your eye,
signal the central circadian clock
that it's the end of the day,
and there's a really nice study
that was published last year,
and I will put links to
these references on a website
not too long from now,
there was a really nice study that showed
that viewing sunlight around
the time of the sunset,
doesn't have to be just
crossing the horizon,
but circa sunset,
within an hour or so of sunset,
prevents some of the bad effects of light
in preventing melatonin
release later that same night,
so let me repeat this,
viewing light early in the day is key,
viewing light later in the day
when the sun is setting,
or around that time,
can help protect these
mechanisms, your brain and body,
against the negative effects
of light later in the day,
so let me talk about you would do that,
you'd go view the sunset
or you would go outside in
the late afternoon or evening,
again, if you safely can do that
with sunglasses off, you will,
if you need to wear sunglasses, fine,
but it will take probably
100 to 1,000 times longer
with dark sunglasses than
if you take them off,
again, if you wanna do this
through a window at work,
that's fine, but it'll
take 50 times longer,
so the best thing to do is
just to get outside for a few minutes,
anywhere from 2 to 10 minutes,
also in the afternoon.
Having those two signals
arriving to your central clock
that your body, your internal world,
knows when it's morning and
knows when it's evening,
is tremendously powerful.
Maybe think about it this way,
every cell in your body
needs glucose and energy,
it needs, whether or not
it gets that from meats
or it gets it from ketones or
it gets it from carbohydrates
or fruit or vegetables, it doesn't matter,
it is eventually converted
into a certain form of energy
that all your cells use,
but you don't take glucose,
you don't take bread or
a steak or a nice orange
and shove it in your ear,
you put it in your mouth,
it goes into your stomach, it's digested,
and then that resource is distributed
to all the cells of your body.
Every cell in your body needs oxygen,
and you don't put a hose
you know, through your
nostril or through your ear
or through some other
orifice in your body,
you inhale air and it's then
distributed via the lungs
to the cells in your blood stream,
and then it's distributed to
all the organs of your body.
Every cell and organ in your
body needs light information,
and the way to get that light information
to all those cells,
because you have a thick skull
and the inside of you is
dark inside your skin,
there's no sunlight getting in there,
is by viewing sunlight with your eyes
at the two times of day
that I'm referring to, okay?
That's the only route.
There was a study published in "Science,"
an excellent journal,
well over 10 years ago,
that showed that light shone
on the back of the knee
could set these circadian rhythms,
that study was retracted,
and unfortunately, most people don't know
that it was retracted,
there were some experimental flaws,
that people were actually viewing light
through their eyes.
That study was repeated,
turns out, there is no
extraocular photo reception in humans.
Whatever somebody tells you
that light to the skin
or light to the wherever
is beneficial for your health,
we can talk about that,
but there's no way that light information
is setting your clocks,
you need these cells in your eyes
to perceive or to see light
at the particular times of
day that I'm referring to.
Some animals, like snakes
and other reptiles,
actually have a hole in
the top of their skull
to get light information
directly to their pineal
to suppress melatonin.
We don't have that hole,
I mean, most of you don't
have holes in your skull.
These holes in your skull
that we call the sockets for the eyes
are actually there primarily
to allow light information
to this central clock,
and then vision and pattern
vision and color vision
came much later in evolution,
we know this on the
basis of genetic studies
we get to discuss in a future podcast.
So get that light information
to the cells of your brain and body
by viewing sunlight at
the two times of day
that I referred to.
There's always a lot of questions about,
"How long, how much, how do
I know if I've had enough?"
You'll know because your rhythm
will start to fall into
some degree of normalcy,
you'll start to wake up
at more or less the same time each day,
you'll fall asleep more easily at night,
generally, it takes
about two or three days
for these systems to align,
so if you've not been
doing these behaviors,
it's gonna take a few days,
but they can have tremendous benefits,
and sometimes rather quickly,
on a number of different
mental and physical aspects
of your health.
Now let's talk about
the bad effects of light
because light is not supposed
to arrive in our system
at any time,
and nowadays, because of
screens and artificial light,
we have access to light
at times of day and night
that normally we wouldn't.
Now, earlier I said that
you need a lot of light,
in particular, sunlight,
to set these clock mechanisms,
that's true, but there's a
kind of diabolical feature
to the way all of this works,
which is the longer you've been awake,
the more sensitive your retina
and these cells are to light,
so that if you've been
awake for 10, 12, 14 hours,
it becomes very easy for
even a small amount of light
coming from a screen or
from an overhead light
to trigger the activation of the clock
and make you feel like
you wanna stay up later,
make it harder to fall asleep,
and disrupt your sleep pattern, okay?
So the simple way to think about this is
you want as much light
as is safely possible
early in the day, morning
and throughout the day,
including blue light,
so take those blue
blockers off during the day
unless you have a real issue
with screen light sensitivity,
and you want as little
light coming into your eyes,
artificial or sunlight,
after, say, 8:00 p.m.,
and certainly, you do not want to get
bright light exposure to your eyes
between 11:00 p.m. and
4:00 a.m., and here's why,
David Berson, who I mentioned before,
and another and friend and
colleague, Samer Hattar,
who's director of the chronobiology unit
at the National Institutes
of Mental Health
published a paper in
"Cell," which is a journal,
another excellent journal,
very high stringency,
showing that light that
arrives to the eyes
between 11:00 p.m. and
4:00 a.m., approximately,
suppresses the release of dopamine,
this neuromodulator
that makes us feel good,
and it's sort of an
endogenous antidepressant,
and can inhibit learning
and create all sorts of
other detrimental effects,
it does this through a mechanism,
for those of you that wanna
know the neural pathways,
that involves light to the eyes
that's then signaled to a
structure called the habenula,
the habenula looks like
two little bat ears
sitting right in the middle
of a structure in your brain
called the thalamus,
don't worry about these names
if you're not interested in this stuff,
if you are, these are
just avenues to explore,
when that habenula gets activated
it's actually called the
disappointment nucleus
because it actually
makes us feel less happy
and more disappointed,
and can lead to certain
forms of depression
in the wakeful state.
Now, if you wake up in
the middle of the night
and you need to use the bathroom
or you're on an all-night flight
and you're, you know, need to
read or whatever it is, fine,
every once in a while,
it's not gonna be a problem
to get bright light exposure to your eyes
in the middle of the night,
but if you think about
our lifestyle nowadays
and being up late looking at phones,
even if you dim that screen,
you're triggering this activation
because your retinal sensitivity
and the sensitivity of
these neurons has gone up
late in the day.
Now, I'm not here to dictate
what you should or shouldn't do,
but for those of you that are
experiencing challenges with mood,
those of you that have anxiety,
learning problems, issues focusing,
the questions I usually get
are, "How can I focus better?"
Well, we will get to that,
but one of the best ways you can support
your mechanisms for good
mood, mental health,
learning, focus, metabolism, et cetera,
is to take control of this
light exposure behavior at night
and not get much or any
bright light exposure
in the middle of the night.
Red light won't trigger this pathway,
but very few people have
the kind of infrared lights
that are set up, or floor lights,
and that brings me to an important point,
which is about the location of light,
this hasn't been discussed
much out there, I don't think,
these cells in our eye,
these neurons that
signal the central clock,
reside mostly, not
exclusively, but mostly,
in the bottom half of our retina,
and because we have a lens
in front of our retina,
and because of the optics of lenses,
that means that these cells
are actually viewing
our upper visual field,
there's an inversion of the
visual image, et cetera,
you can look that up
if you wanna learn more
about retinal optics, it's fascinating,
but not the topic for today.
These cells are in the bottom
half of your retina mostly,
and so they're viewing the
overhead visual space around you.
This is probably not
coincidental that these cells
were essentially designed
to detect sunlight,
which is overhead, of course,
so if you want to avoid
improper activation of these neurons,
it's better to place lights
that you use in the evening
low in your physical environment,
so on desktops or even the
floor, if you wanna go that way,
as opposed to overhead lights,
so overhead florescent
lights would be the worst,
that would be the worst case scenario,
lights that are overhead
that are a little bit softer,
of the sort or yellow or reddish tints,
would be slightly better,
but dim lights that
are set low in the room
are going to be best
because they aren't going
to activate these neurons
and therefore shift your circadian clock,
so that's a goal.
Some people, like Samer Hattar
that I mentioned earlier,
he turns his home basically
into a cave in the evenings.
Candlelight actually does not
trigger activation of these cells,
so candlelight and fireplaces
and campfires are fine,
dim lights, very dim lights are fine,
and lights low in the
physical environment,
of course, the problem with
candlelight and fireplaces
is the fire hazard,
but you're smart people, you
know what to do about that.
Don't burn down whatever
structure you're in,
including forests, please.
So, keep the lights low
in in your environment.
What if you wake up in
the middle of the night
and you find yourself watching
TV or on the computer?
Well, in that case, you might
wanna wear blue blockers,
and you certainly would
wanna dim the screen,
but ideally, you're not doing that,
it's remarkable the positive effects
of getting that bit of
sunlight early in the day,
maybe even also around sunset,
and avoiding bright lights,
and especially overhead bright lights,
between about 11:00 p.m. and 4:00 a.m..
Now, I'm not talking about shift work,
I'm realizing that we're probably
gonna have to have an entire discussion
devoted just to shift workers
because there's some
good information there
about how they can protect themselves
against some of the very bad
health effects of shift work,
of getting light in the
middle of the night,
but we rely on shift workers
and they're super important to culture
and society and the economy,
so I wanna acknowledge them
and let you know that
we will do a discussion
about shift work and jet lag,
but let's talk about what light can do
in terms of shifting us in healthy ways.
So the way to think
about this whole system,
again, is you've got adenosine building up
depending on how long you've been awake
and it's making you sleepy,
and then you've got the
circadian mechanisms
that are timing your wakefulness
and timing when you wanna be asleep,
mainly through cortisol and melatonin,
but there are a bunch of other things
that are downstream of
cortisol and melatonin,
like, we tend to be hungrier
during our wakeful period
than late at night,
some people like to eat late at night,
but if you're finding that you
can't become a day person
or a morning person,
shifting your light exposure, exercise,
and food intake to the daytime will help.
Some people like to stop
eating around 6:00 or 8:00 p.m.
because of metabolic reasons
or they're trying to maintain
their weight or lose weight,
that's actually not supported
so well by the literature,
the literature around
nutrition essentially says
that it's best to restrict your feeding
to a certain period of each 24-hour cycle
to not be eating around the clock,
and whether or not that's 4
hours or 8 hours or 16 hours
is a much lengthier discussion
than we have time for now,
I would refer you to Satchin Panda's book,
"The Circadian Code,"
which talks all about that,
he's an expert, a former colleague of mine
from the Salk Institute in San Diego,
you can explore intermittent
and circadian fasting,
so to speak, through Satchin's literature,
we'll talk about that,
we might even get Satchin
in here if we're lucky
at some point in the future,
but you can actually use
light to wake up earlier.
Jamie Zeitzer and colleagues
did a beautiful study
showing that, if you turn on
the lights before waking up,
so around 45 minutes to
an hour before waking up,
even if your eyelids are closed,
provided you're not under the covers,
after doing that for a few days,
that increases your total sleep time
and shifts forward the time
at which you feel sleepy,
it makes you want to go
to bed earlier each night.
Now, in a kind of diabolical way,
they did this with teenagers
who are notorious for
wanting to wake up late
and stay up late,
and what they found was
bright light flashes,
just turning on the lights
in their environment, overhead lights,
because they're trying
to activate this system
and that's why they're
using overhead lights,
even through the eyelids,
before these kids woke up,
then made those kids naturally
wanna go to bed earlier
and they ended up sleeping longer,
so that's something you could try,
you could put your lights on a timer
to go on early in the
day before you wake up,
you could open your blinds
so that sunlight is coming through,
and again, if you curl
up under the covers,
then it's not gonna reach these neurons,
but it's remarkable that light
can actually penetrate the eyelids,
activate these neurons, and
go to the central clock.
That study illustrates a
really important principle
of how you're built,
which is, you have the capacity
for what are called phase
advances and phase delays,
and I don't wanna
complicate this too much,
so the simplest way to think about
phase advances and phase delays
is that if you see light late in the day,
and in particular, in
the middle of the night,
your brain and body, for
reasons that now you understand,
will think that that's morning light
even though it's not sunlight
because you have this
heightened sensitivity,
and it will phase delay,
it will delay your clock,
it will essentially make
you want to get up later
and go to sleep later,
so if you get light exposure
too late in the evening
or in the middle of the night,
it's going to make it hard
to want to wake up that next morning early
and to go to bed early.
The opposite is also true,
if you wake up early,
say, 6:00 a.m. or 7:00 a.m.,
and get light exposure,
or even earlier, 4:00 a.m.,
and get light exposure,
it will phase-advance your clock, okay?
It's gonna make your
clock think it's earlier
and you'll wanna wake up earlier,
so the simple way to think about this
is if you're having
trouble waking up early
and feeling alert early in the day,
you're going to wanna try
and get bright light exposure
even before waking up because
it will advance your clock,
it's sort of like turning
the clock forward,
whereas if you are having
trouble waking up early,
you definitely don't want to get
too much light exposure
or any light exposure
to your eyes late in the evening
and in the middle of the night
because it's just gonna delay
your clock more and more,
so rather than get into the specifics
of everybody's situation
because there are many of you out there
with different situations
and lifestyle requirements, et cetera,
the way to think about this
is that you have these internal mechanisms
of adenosine and circadian clocks,
and they're always operating,
and what you're trying to
do is provide them anchors,
you're trying to provide them
consistent, powerful anchors
so that your cortisol, your melatonin,
and then everything that
cascades down from that,
like your metabolism and
your ability to learn
and your sense of alertness,
your dopamine, your serotonin,
all that stuff is timed regularly,
one of the reasons why there's
so much challenge out there
with focus and anxiety and depression,
there are a lot of reasons for that,
but one of the reasons is that
people's internal mechanisms
aren't anchored to anything regular.
Now, this doesn't require
being neurotically attached
to getting up at a very
specific time, going outside,
viewing the sunlight at
the same time every day,
these systems, again, will average,
but if you can provide them
consistent light anchors
early in the day and in the evening,
and avoiding light at night,
you will be amazed at
the tremendous number
of positive effects
that can come from that
at the level of metabolic
factors, hormones,
and just general feelings of wellbeing,
in fact, most of us are familiar
with what it is to not sleep well
and all the terrible effects that has,
maybe one night you're
fine, two nights even,
for the new parents out
there, I sympathize with you,
but most people are not
familiar with what it is
to sleep really, really
well on a consistent basis,
and when you start doing that
by controlling your
sleep environment, right,
get the proper sleep surface,
get the proper pillow,
get the temperature in the room right,
get your light exposure right,
start timing your exercise
at normal periods or times
throughout the day and week,
it's amazing how many
other biological systems
just naturally fall in line,
and this is why whenever people ask me,
"What should I take?"
which is one of the most
common questions I get,
"What supplement should I take?
"What drug should I be taking?
"What things should I be taking?"
The first question I always ask
them is, "How's your sleep?"
and 90% of the time, they tell me
they either have trouble
falling asleep or staying asleep
or they don't feel rested
throughout the day.
A brief note about naps,
naps, provided that they're
less than one ultradian cycle,
provided they're 20 minutes
or 30 minutes or even an hour,
can be very beneficial
for a lot of people,
you don't have to take them,
but many people naturally feel a dip
in energy and focus late in the afternoon,
in fact, if we were gonna
look at wakefulness,
what we would find is that you get
that morning light exposure, hopefully,
your cortisol goes up, people
will start feeling awake,
and then around two, or three,
or four in the afternoon,
there's a spike in everything
from alertness to ability to learn,
some metabolic factors drop,
and then it just naturally comes back up,
and then it tapers off
as the night goes on.
So for some of you, naps are great,
I love taking naps,
some people, they wake up from
naps feeling really groggy,
that's probably because
they're not sleeping
as well as they should at night
or as long as they should at night,
and so they're dropping into REM sleep
or deeper forms of sleep in the day time,
and then they wake up and
they feel kind of disoriented,
other people feel great after a nap,
so that's another case where,
just like with caffeine,
so sort of have to evaluate for yourself.
As we discuss this,
you're probably realizing
this is a lot like nutrition
where nowadays it's just crazy,
I mean, if you go on social media,
it's like you've got people
who are pushing carnivore,
you've got other people
who are pushing vegan,
other people who are pushing paleo,
every variation of every diet,
and there's a lot of data to support
any and all of those and
the arguments go on and on,
and there's probably a
lot of genetic variation
and lifestyle variation
that's going to dictate whether or not
something is good for you,
whether or not you like it,
whether or not you'll stick to it.
The same thing is true for circadian
and sleep and wakefulness behaviors,
except the light-viewing behavior
that I talked about before,
there's no way around that,
that's hardwired into our system,
the same way we could factually say
that everybody needs some nutrition
at some level from some source,
everybody needs light information
arriving in their system in
some way at regular intervals,
so that's really what this is about.
Okay, so naps are gonna
be good for some people,
not for others,
I have a colleague, a very
accomplished neuroscientist,
who likes to take naps just after lunch,
I personally like to take a
nap around 3:00 or 4:00 p.m.,
but there's a practice
that I've adopted in the last 5 years
that I've found to be immensely beneficial
that is sort of like
napping but isn't napping,
it's a thing that they call yoga nidra,
yoga nidra actually means yoga sleep,
and it's a sort of meditation
that you listen to,
there are number of scripts,
I've talked about this on podcasts before
but I'm going to post a link
to the two that I like most,
that allows you to consciously
bring your entire body and mind
into a state of deep relaxation,
and sometimes you fall asleep
and sometimes you don't,
this is done for 10 to 30 or
even 60 minutes at a time.
The other thing that works
really well is meditation,
so I'm talking about naps,
but I'm also talking about yoga nidra,
which is sort of a form of meditation,
and then more standard
forms of meditation,
all three of those do something powerful
which is that they bring our mind
into a state of less so-called
sympathetic nervous system activation,
go back and listen to episode one
if that doesn't make any sense,
which is what governs your alertness,
and instead, it activates
cells and circuits in your body
that promote the
parasympathetic nervous system,
or the calming system.
A lot of people are
not good falling asleep
because they're not good at calming down,
so some people have no
trouble falling asleep,
but many people have a
hard time falling asleep,
or at least every once in a while
experience challenges falling asleep.
I don't have problems
falling asleep most nights,
but I've noticed that
if I'm working very hard
or if the world is particularly stressful,
my mind gets into a bit
of a kind of OCD loop
where I tend to ruminate on things,
and I'm not even thinking
about anything in particular,
it's just challenging for me
to disengage and fall asleep.
Meditation and yoga nidra scripts
have been immensely helpful for me
in terms of accelerating
the transition to sleep,
so they involve taking a few minutes,
10 to 30 minutes or so,
just like you would for a nap,
and just listening to a
script, almost passively,
and it has you do some
particular patterns of breathing
and some other kind of
body-scan-like things
that can really help
people learn to relax,
not just in that moment,
but get better at relaxing
and turning off thinking
in order to fall asleep when
they wanna do that at night.
There's another thing
that's similar to this,
which is certain forms
of hypnosis for sleep,
for that, I'll just
refer you to the website
of a colleague and collaborator of mine,
David Spiegel, who's our associate chair
of Psychiatry and Behavioral
Sciences at Stanford,
he's developed a website,
which is reverie,
R-E-V-E-R-I-E, health.com,
so reveriehealth.com,
that has a lot of science-supported,
clinically supported hypnosis scripts
that essentially take the brain
into states of deep relaxation
for the sake of rewiring the
brain and neuroplasticity,
but one of those scripts that's there
and is available free is for sleep,
and we'll talk more about
hypnosis at a later time
because it has a ton of other effects
that aren't just limited to sleep.
So a period of time each day
that you devote to getting better
at falling and staying asleep
is actually a really
good practice to adopt.
The other thing about these practices
like meditation, yoga nidra, and hypnosis,
is people would always say to me,
"Well, when should I do them?"
and I always say, "Well, the
best time of day to do it
"is when you first wake up in the morning,
"provided you've gotten
your sunlight already,
"anytime you wake up in
the middle of the night,
"or any time of day."
In other words, they're
always good for you
because it's a training mechanism
by which you self-train
your nervous system
to go from a state of heightened alertness
that you don't want
to heightened relaxation that you do want,
and so it's really teaching
you to hit the brake,
and that brings us to an even
more important point, perhaps,
which is, we've all experienced
that we can stay up if we want to, right?
If we wanna stay up late on New Year's
or we wanna push an all-nighter,
some people can do that
more easily than others,
but we're all capable of doing that,
but it's very hard to make
ourselves fall asleep,
and so there's a sort of asymmetry
to the way our autonomic nervous system,
which governs this
alertness-calmness thing,
the sympathetic and
parasympathetic nervous system,
there's an asymmetry there
where we are more easily
able to engage wakefulness
and drive wakefulness,
we can force ourselves to stay awake,
than we are able to force
ourselves to fall asleep,
and one of the things that
I say over and over again,
and I'm gonna continue to
say over and over again,
is it's very hard to control
the mind with the mind,
when you have trouble falling asleep,
you need to look to some
mechanism that involves the body,
and all the things I described,
meditation, hypnosis, yoga nidra,
all involve exhale-emphasized breathing,
certain ways of lying down
and controlling the body,
we're gonna get into
breathing in real depth
at another time,
but all of those involve using
the body to control the mind
rather than trying to, you know,
wrestle your mind into a
certain pattern of relaxation,
so earlier in episode one, I
talked about the Mobius strip,
this continuous loop that is
the brain-body relationship,
or the mind-body relationship,
and when we're having
trouble controlling the mind,
I encourage people to
look towards the body,
look toward sunlight,
avoid sunlight and bright light
if that happens to be late at night,
so there's a theme
that's starting to emerge
which is, in order to control this thing
that we call the nervous system,
we have to look back to
some of the things we discussed earlier,
like sensation, perception, et cetera,
but we have to ask, what can we control?
Well, I'm talking about
controlling light exposure,
controlling your breathing and body,
I'm not going into details right now
but you can see the yoga nidra script
or the reveriehealth.com,
or Headspace would be a great place
to adopt a meditation practice,
any of those are really teaching you
to use your body to control your mind,
and to allow you to explore
the mind-body relationship
in a way that gives you more control
over your mind and the
mind-body relationship, okay?
So we talked about light,
we talked about activity
and timing of light,
we talked about the usefulness of naps,
and these things that I'm
calling non-sleep deep rest,
which include meditation,
yoga nidra, and hypnosis,
non-sleep deep rest,
or what I, hereafter, we
will refer to as NSDR,
not to be confused with EMDR,
I don't think I've ever heard NSDR,
so I'm planting a flag for
NSDR, non-sleep deep rest,
as a way to reset one's
ability to be awake
after you emerge from NSDR,
so to get some more wakefulness
and ability to attend,
some emotional stability, reset,
as well as make it better
and easier to fall asleep
when you wanna go to sleep at night.
Now, the non-sleep deep rest
does have some research to support it,
there's a beautiful study done
out of a university in Denmark,
I will later provide a link to that study,
that showed that this meditation
and yoga nidra-type meditation
allows dopamine and other neuromodulators
in an area of the brain
called the striatum
that's involved in motor
planning and motor execution,
to reset itself,
in other words, this NSDR
can reset our ability
to engage in the world in a
way that's very deliberate,
and not to throw in another acronym,
but NSDR resets your
ability to engage in DPOs,
duration, path, and outcome,
so now you're probably
rolling your eyes like,
"Oh my goodness, the number of acronyms,"
but just bear with me
because NSDR is so powerful,
because first of all, it doesn't require
that you rig yourself to any device,
it doesn't require that you
take much time out of your day,
it doesn't require that you
ingest anything, except air,
and it can have so many positive effects
right down to the neuromodulator level,
so I think in the years to come,
my lab's exploring this
in a collaboration with
David Spiegel's lab,
but other labs are
looking at this as well,
I think NSDR is going to start
to play a more prominent role
in what we call wellness and health,
both mental health and physical health,
so I encourage you to
explore those practices.
Okay, so what about things that we can
and maybe should or should not take
in order to control
and access better sleep
and better wakefulness?
We've talked about things
you can do or not do,
we've talked about nutrition
and the timing of nutrition,
now let's talk about compounds,
those could be prescription drugs,
those could be supplements,
there are a number of different things
that will affect your
circadian timing and behavior,
in fact, almost everything
that you could take
will affect your circadian
timing and behavior,
that's right.
So years ago when I
was in graduate school,
I had a professor, unfortunately,
he passed away now,
but his name was Ted Jones,
the late Edward Jones,
who was a world-class neuroanatomist,
he wrote the book on the thalamus,
in fact, it's called "The Thalamus,"
and an expert on patterns
of activation in the brain
during sleep,
and I'll never forget that
during one of these lectures,
someone asked Ted the question,
"What is the effect of some drug
"on these waves of activity in
the thalamus?" or something,
and his answer was incredible.
Now, he was a pretty gruff guy,
and so his answer was delivered
in the form of a kind of
aggressive direct statement,
he said, "A drug is a substance
"that when injected into a person,
"produces a scientific publication,"
and what he was saying
is actually quite true,
which is that most every compound
will have some effect on
some aspect of biology,
this is why it's hard
to sort through everything
that's on PubMed,
if you put any molecule or
compound or drug into PubMed
and then you put sleep next to
it, or alertness next to it,
you're likely to find a paper
where there's an effect,
but that's not necessarily telling you
that that drug is helpful for that,
what it's telling you is
that anytime you change what you take
or you stop taking something,
say you're taking sleeping
pills, Ambien or whatever it is,
and you stop taking them,
your sleep behavior will change.
Let's stay you take an aspirin
and you don't normally take aspirin,
you will shift your circadian rhythm,
now you might not shift it perceptibly,
you might not create
problems for yourself,
but anytime you ingest a
compound at high potency,
you're going to provide some
shift to your circadian rhythm.
Now, that said, there are a couple things
that are directly in line with the biology
related to falling and staying asleep
and directly in line with
the biology of wakefulness,
there's a whole category of things,
like stimulants, cocaine, amphetamine,
and prescription stimulants, that are,
the prescription ones were designed
for the treatment of narcolepsy,
so things like modafinil or armodafinil
that are designed to created wakefulness,
they are all essentially chemical variants
of things that increase
epinephrine and dopamine.
Now, of course, I'm of the standpoint
that things like cocaine and amphetamine
are just across the board bad,
they have so many addictive
and terrible effects,
in the proper setting prescribed
by the proper professional,
things like modafinil for
narcolepsy might be appropriate,
I know that a lot of people
out there take Adderall,
even though they haven't
been prescribed Adderall,
in order to increase wakefulness,
that is essentially, well,
it's illegal for one,
but also it's abusing the system
in the sense that you're pushing back
on the adenosine system
slightly differently
than you do caffeine,
it will make you feel more alert,
there tends to be a heavy rebound
and they do have an addictive potential,
there are also some other effects of those
that could be quite bad,
so we're gonna explore stimulants
in a whole month related to drugs,
but there are some supplements
and some things that are
safer, certainly safer,
and that, in cases where you're
doing all the right behaviors,
you're exercising and eating correctly
and you're still having
trouble with sleep,
that can be beneficial for
falling and staying asleep.
Now, I wanna be very clear,
I am not pushing supplements,
I am just pointing you toward some things
that have been shown in
peer-reviewed studies
to have some benefit.
The first one is magnesium,
there are many forms of magnesium,
but certain forms of magnesium
can have positive effects on sleepiness
and the ability to stay asleep,
mainly by way of increasing
neurotransmitters like GABA
which help turn off the DPO,
the kind of thinking about the future,
duration-path-outcome analysis,
and make one's mind kind
of drift in space and time
and make it easier to fall asleep,
there are a lot of forms
of magnesium out there,
but in particular is magnesium
threonate, T-H-R-E-O-N-A-T-E,
which you have to check to
see if this is right for you,
check with your doctor,
but magnesium threonate is
associated with transporters in the body
that bring more of it into cells
that allow people to feel
this kind of drowsiness
and help them fall asleep,
so I personally, I can only
talk about what I personally do,
I personally take 3 or 400
milligrams of magnesium threonate
about 30 to 60 minutes before sleep,
and it helps me fall asleep.
The other thing is theanine, T-H-E-A,
T-H-E-A-N-I-N-E, theanine,
100 to 200 milligrams of theanine, for me,
also helps me turn off
my mind and fall asleep,
I take it 30 to 60 minutes
throughout the day.
Interestingly, theanine
is now being introduced
to a lot of energy drinks
in order to take away the jitters
that are associated with
drinking too much caffeine
or with some other things
that are in the energy drinks,
energy drinks can be problematic,
they can contain a lot of L-taurine,
I'll just tell you an anecdote,
when I was a postdoc,
I was drinking a lot of a
particular energy drink,
it has a lot of taurine in it,
and actually the whites of my eyes,
the sclera, as it's called,
of my eyes turned beet red,
and I went to a friend
who's an ophthalmologist,
I said, "Look, I'm not a marijuana smoker,
"I haven't been hit on the head,
"I don't know what's going on,"
and he looked and he said,
"I think you've got some
microvascular damage,"
and we walked through what
I was taking and doing,
and he said, "Oh, it's
probably the taurine,
"excessive levels of taurine
"can create some microvascular damage."
So if you're having
microvascular damage in your eye,
you probably have microvascular damage
deeper in your skull, so I stopped,
that's the reason why I
don't take energy drinks,
so just a consideration,
again, I'm not here to tell
you what to do or not do,
but just wanna arm you with information.
The thing about theanine and magnesium
is taken together, they
do, for some people,
they can make them so
sleepy and sleep so deeply
that they actually have trouble
waking up in the morning,
so you have to play with
these things and titrate them
if you decide to use them,
again, if you decide to go this route,
I would not start by taking supplements,
I would start by getting your
light-viewing behavior correct,
and then think about your nutrition
and then think about your activity
and then think about whether
or not you wanna supplement,
we already talked about melatonin earlier.
There's another supplement
that could be quite useful,
which is apigenin, A-P-I-G-E-N-I-N,
which is a derivative of chamomile,
50 milligrams of apigenin
also can augment or support
this kind of creation of a sleepiness
to help fall asleep and stay asleep.
A note about sleepwalkers and
people with very vivid dreams,
theanine can often make
your dreams very vivid,
sleepwalkers should be
careful about taking theanine,
everyone should be careful
about taking anything,
and don't take anything
without consulting your
board-certified M.D.
or healthcare professional first, okay?
Your health is your responsibility,
I am not gonna take responsibility
for what you decide to do
experimentally in any case,
but especially as it relates
to supplementation and drugs.
As a important point, apigenin
is a fairly potent estrogen inhibitor,
so women who want to keep
their estrogen levels high,
or at whatever levels
they happen to be at,
should probably avoid apigenin altogether,
and men, take that into
consideration as well,
men need estrogen also,
you don't wanna completely
eliminate your estrogen,
that it can create all
sorts of bad effects
on libido and cognition, et cetera,
so apigenin in some people
is gonna be a pretty
strong estrogen inhibitor,
so keep that in mind.
There are other things you can take
to help you sleep better,
those are the legal ones
that, at least I'm aware of,
have pretty broad safety margins,
but again, you need to explore
your safety margins with any compound.
I think a great website
that I can refer you to is examine.com,
examine, the word, just as it
sounds, .com, is a website,
I have no relation to them,
but there, you can find links
to peer-reviewed studies
for any compound or supplement,
as well as some important warnings
related to the things I discussed,
as well as any other thing
that you might decide to supplement with
or ingest to help improve your sleep.
Okay, that was a lot of information
about how to get better at sleeping,
falling asleep, wakefulness, et cetera.
An important feature of
this podcast, as you know,
is that we dive deep into topics
for several episodes at a time,
at least a month at a time,
so by stopping here, I recognize
that there are probably
many more questions
that you still have,
and the great thing about that
is that we have another
episode coming up soon,
I'm going to hold office hours
where I'm going to answer
your specific questions
about episodes one and two,
so if you have questions
about this episode,
you have questions about episode one,
write them down, put them in the comments,
I'll also do a post on Instagram
where you can put them
in the comments there,
but put them in the comments
to this episode as well,
please recommend the
podcast if you like it,
please subscribe to it here on YouTube,
please subscribe to it on Apple,
we're now on Spotify as well,
recommend it to a friend,
the community that we're creating here
around these topics of
sleep and wakefulness
and other neuroscience-
and health-related themes
is best supported by your
involvement and your questions,
and so I'm going to be
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distilling those into the
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and then we can move forward
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these critical topics
around sleep and wakefulness
so that you can be armed
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and resources that you need.
Last but not least, a number of you
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So thank you so much for
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(energetic music)