Welcome to the Huberman Lab Podcast,
where we discuss science
and science-based tools for everyday life.
I’m Andrew Huberman,
and I’m a professor of neurobiology and ophthalmology
at Stanford School of Medicine.
Today, my guest is Dr. Gina Poe.
Dr. Gina Poe is a professor
in the Department of Integrative Biology and Physiology
at the University of California, Los Angeles.
Her laboratory and research focuses on the relationship
between sleep and learning,
in particular, how specific patterns of brain activity
that are present during specific phases of sleep
impact our ability to learn
and remember specific types of information.
For instance, procedural information,
that is, how to perform specific cognitive
or physical tasks,
as well as encoding of emotional memories
and discarding emotional memories.
Indeed, her research focuses
on how specific phases of sleep
can act as its own form of trauma therapy,
discarding the emotional tones of memories.
In addition, her laboratory focuses
on how specific phases of sleep
impact things like the release of growth hormone.
Growth hormone, of course, plays critical roles
in metabolism and tissue repair,
including brain tissue repair,
and therefore has critical roles in vitality and longevity.
Today, you will learn many things
about the relationship between sleep, learning,
emotionality, and growth hormone.
One basic but very important takeaway
that you’ll learn about today, which was news to me,
is that it’s not just the duration
and depth of your sleep that matter,
but actually getting to sleep
at relatively the same time each night
ensures that you get adequate growth hormone release
in the first hours of sleep.
In fact, if you require, let’s say,
eight hours of sleep per night,
but you go to sleep two hours later
than your typical bedtime on any given night,
you actually miss the window for growth hormone release.
Getting growth hormone release in sleep,
which is absolutely critical
to our immediate and long-term health,
is not a prerequisite of getting sleep,
even if we are getting enough sleep.
As Dr. Poe explains,
there are critical brain circuits and endocrine,
that is hormone circuits,
that regulate not just the duration and depth
and quality and timing of sleep,
but when we place our bout of sleep,
that is when we go to sleep each night,
plus or minus about a half hour or so,
strongly dictates whether or not
we will experience all the health-promoting,
including mind-promoting benefits of sleep.
Today’s episode covers that
and a lot more in substantial detail.
You will learn, for instance,
how to use sleep in order to optimize learning,
as well as forgetting for those things
that you would like to forget.
So during today’s episode,
Dr. Gina Poe shares critical information
about not just neuroscience,
but physiology and the hormone systems of the brain and body
that strongly inform mental health,
physical health, and performance.
So by the end of today’s episode,
you’ll be far more informed about sleep and how it works,
the different roles it performs,
and you’ll have several new actionable steps
that you can take in order to improve your mental health,
physical health, and performance.
Before we begin, I’d like to emphasize that this podcast
is separate from my teaching and research roles at Stanford.
It is, however, part of my desire and effort
to bring zero cost to consumer information about science
and science-related tools to the general public.
In keeping with that theme,
I’d like to thank the sponsors of today’s podcast.
Our first sponsor is Element.
Element is an electrolyte drink
that has everything you need and nothing you don’t.
That means plenty of salt, magnesium, and potassium,
the so-called electrolytes, and no sugar.
Now, the electrolytes are critical
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in particular, the neurons, the nerve cells.
As I’ve talked about before on this podcast,
neurons, nerve cells, require adequate sodium and potassium,
as well as magnesium, in order to fire action potentials,
which are the electrical signals
that allow neurons to do everything
from generate focus and attention,
allow you to learn, and generate neuromuscular connection,
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Sleep is the foundation of mental health,
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And now for my discussion with Dr. Gina Poe.
Dr. Gina Poe, welcome.
I’ve really been looking forward to this conversation
because I’m familiar with your work,
and I know that many people are going to be excited
to learn about your work as it relates to sleep,
as it relates to problem solving, creativity,
addiction and craving, relapse,
and a number of other important topics.
So to start things off,
I would love for you to educate us a bit
about this thing that we are all familiar with,
and yet very few of us understand, which is sleep.
And if you would, could you describe the various phases
of sleep that exist, what distinguished them,
and perhaps frame this within the context
of what would a perfect night’s sleep look like?
How long would it last, more or less?
And what would the biology look like?
What is a perfect night’s sleep?
Oh yeah, that’s a great question.
All right, so sleep is really different from wakefulness,
and in fact, can’t be replaced by any state of wakefulness
that we’ve been able to come up with so far.
Our brain chemistry is completely different,
and in the different stages of sleep,
which there is non-REM and REM,
are the two major states of sleep,
and every animal we’ve studied so far
seems to have both of those states.
Anyway, those two states are entirely different
from one another, too.
And even within non-REM, there are three states.
Stage one, which is what you slip into
when you’re first falling asleep, it’s dozing.
There’s kind of an interesting rhythm
that goes on in the brain.
It’s kind of a fast gamma rhythm.
And then there’s stage two, which is a really cool state.
We sort of used to ignore sleep researchers
because it was a transient state between wakefulness
and the deep stage three slow-wave sleep,
which is the most impressively different,
and between that and REM sleep.
So stage two, I’ll talk a little bit more about.
And then the deep slow-wave sleep state,
which is when big slow waves sweep through our brain,
and now we realize that it cleans our brain.
One of the things that those big slow waves do
is cleans our brain and does other really important things
to restore us from a day of wakefulness.
And then REM sleep, which is the most popular
because that’s where we have the most active dreams
and when you wake up someone out of REM sleep,
they’ll almost always report having dreamed
something really bizarre.
That’s called REM sleep, rapid eye movement sleep.
So those are the four states of sleep, of human sleep,
and we cycle through them every 90 minutes or so.
When we go to sleep, say 10, 10.30, 11 o’clock,
our first REM sleep period comes about 105 minutes
after we fall asleep and lasts about 20 minutes.
It comes about 95 minutes and lasts 10 or 15 minutes.
And then we start over again,
and we have about five of those per night
for a perfect night’s sleep,
four or five, something like that.
So a perfect night’s sleep is seven and a half, eight hours.
There was a really great study that put people
in a semi-darkened room with nothing but the bed
for 12 hours every day for a month.
And what people did initially is,
because we’re in a sleep-deprived nation,
is that they slept a lot more than usual,
like 10 or 11 hours of the 12.
And then they leveled off after a week or two
to about eight hours and 15 minutes of sleep.
So you actually can’t oversleep.
I mean, they had nothing else to do but sleep,
and they would round off to, on average,
eight hours and 15 minutes a night,
and then they spend the rest of the time twiddling
their thumbs, humming tunes, daydreaming.
I want to get back to the contour of a perfect night’s sleep,
but I’m intrigued by this idea that people can’t oversleep.
I’m often asked whether or not we can get too much sleep
and whether or not sleeping too long, excuse me,
can make us groggy the next day.
Is there anything to that?
And how does one determine how long they should sleep
On average, yeah, well, that’s interesting
because different people need,
seem to need different amounts of sleep,
but we don’t really even know exactly what sleep is for.
So what they need is, you know,
kind of, it’s, you know, murky.
So we do know a lot of things that sleep does now for us,
but we don’t know how long those things take.
So how long we need to sleep
is also just a big question mark.
But some people don’t feel rested
until they’ve slept nine hours,
and some people don’t feel rested
after three or four and a half.
But most people,
if they consistently deprive themselves of sleep
so that they’re only sleeping
four, four and a half hours a night,
build up a cognitive deficit that just builds up over time.
The more nights you have with sleep deprivation,
the more cognitive deficit you have.
And so you need sleep, again, to sleep more to recover.
Now, the question you had about-
Can you oversleep?
Can you oversleep, right.
Can you sleep to the point where it’s too much?
You know, that we, I, growing up when I was in high school,
my girlfriend’s dad had this belief
that no one should sleep in past 6 a.m.
So he would wake all the,
there were two children in that home.
He would wake up the kids in that house.
He had this thing against oversleeping,
regardless of when people went to sleep.
And I always thought that was an interesting mentality.
It’s not terrible, actually,
because what that will do is it’ll put you,
make you sleepier the next night to get to bed on time.
So it’ll build up your homeostatic need
if you wake up too early.
But, so I don’t think you can oversleep,
but people who sleep a lot,
like people who sleep over nine hours,
it’s probably indicative of some other problem
because, in fact, if you have a lot of different conditions,
it will cause you to sleep a lot more,
probably because what it does is it interferes
with your efficient sleep, the efficiency of your sleep.
So if you find yourself sleeping consistently
nine hours plus every night,
then you might want to consult a doctor
about maybe what else it might be.
It could be cancer.
It could be sleep apnea,
that just affects a lot of people.
It could be that your sleep is super inefficient
because you’re snoring a lot more than you know,
or you’re waking up a lot more than you know every night.
So you might want to sleep study
just to see how your sleep is
and then see what else might be causing you to sleep so much.
And that wouldn’t be if somebody is sleeping
nine or 10 hours, you know, every once in a while.
You mean if they’re consistently sleeping
for more than nine hours.
If they feel like they need it
in order to function cognitively the next day,
it might be that your sleep is just not efficient
and you might want to look into why that’s the case.
Forgive me for the anecdote, but I can’t resist.
Years ago, I went to an acupuncturist
and he gave me these red pills
of which I don’t know what they contained.
But I took them because he told me
they would help with my sleep.
And I would fall asleep about 30 minutes after taking them.
And I would have incredibly, excuse me, vivid dreams.
And I’d wake up four or five hours
after having gone to sleep feeling completely rested.
Something that I’ve never really experienced
on a consistent basis.
I want to do mass spec on these pills.
I still have no idea what was in them whatsoever.
I want to do mass spec on those pills too.
Some people thought that perhaps they had GHB,
gamma hydroxybutyrate, which is by the way,
an illegal drug, it can kill you.
It’s not something you want to take.
No, that’s not good.
But anyway, if ever someone can figure out
what the red pills were, I’ll be very-
That’s really great.
And this is not a red pill of the other sort red pill.
This is just the red sleep pills.
I mean, it could have been even a placebo effect
because placebo is extremely strong.
Although I don’t know,
there was really something to these red pills.
So shout out to the acupuncturists and the Eastern medicine.
But to return to this idea of the architecture
of a perfect night’s sleep.
So you said we fall asleep,
the first 90 minutes of sleep, REM sleep,
rapid eye movement sleep,
will arrive at about 95 minutes in.
Does that mean that the rest of that 90 minutes
is consumed with slow wave sleep?
Yeah, non-REM sleep.
Okay, and what about the sleep where we are lightly asleep
and we might have a dream that has us
somehow thinking about movement
or that we jolt ourselves awake?
That often happens early in the night, right?
Yeah, that’s the first stage, stage one
and stage two of sleep.
And stage two sleep is really cool
because that has something called sleep spindles
And what sleep spindles are a little bit of activity
that’s 10 to 15 Hertz in frequency.
It’s a conversation between the thalamus and the cortex.
So the thalamus is the gateway to consciousness
and the neocortex processes all our cognition.
And so it’s these spindles, they’re called sleep spindles.
And if you wake up out of that state,
you will often report a dream,
like a hallucination style dream.
It won’t be a long dream report
like you have out of REM sleep,
but it will be some hallucination state.
And during, while we’re falling asleep,
one of the reasons we call it falling asleep
is because in stage one and stage two,
our muscles are relaxing.
And if there’s part of our brain that’s conscious enough
to sort of recognize that relaxation,
we’ll feel like we’re falling and we’ll jerk awake.
So often that hallucination,
it’s called hypnagogic hallucination,
will feel like it’ll include some falling aspect
that we’ll wake up out of.
That’s really interesting to me.
I’ve long felt that sensation
almost like dropping back into my head,
so much so that if I elevate my feet just slightly
and I tilt my head back just slightly
in order to go to sleep,
I find that I fall asleep much faster.
But it does feel as if I’m gonna fall,
like almost gonna do a backwards somersault.
I actually really like the sensation
and usually because it precedes falling deeply asleep.
Yeah, that’s really interesting.
Somebody has to do a study of elevated feet.
Yeah, there’s a little bit on body position and sleep
and some of the washout that we’ll talk about.
So early in the night,
you’ve got these lighter stages of sleep,
less rapid eye movement sleep.
What can we say about the dreams that occur
during the say first and second,
you know, 90 minute cycles of sleep?
Are they quite different than the patterns of sleep
and dreaming that occur later in the night
or toward morning?
Well, okay, that’s an interesting question.
There’s a lot of facets to it.
There is some evidence that the first four hours of sleep
are very important for memory processing.
And in fact, if you’ve learned something new that day
or have experienced a new sensory motor experience,
then your early sleep dreams
will incorporate that experience
much more than the later sleep dreams.
Later is that memory gets consolidated
from the early structures,
which are the hippocampus deep in the temporal lobe
to the cortex in a distributed fashion.
That memory seems to move
from that hippocampus to the cortex
and also the dreams that incorporate that memory
also move later in the night.
So nobody knows why,
but there was a great study by Siddhartha Ribeiro
who studied the consolidation of memories
from the hippocampus to the cortex in a rat
across the period of a full day’s sleep
because rats sleep in the daytime.
And he found that each subsequent REM sleep period
moved that memory from the hippocampus
to the first area that projects to it
and then the second area and then the third area.
And you can see the memory moving
throughout the sleep period.
Very cool, I have to read that study.
So there’s a number of different hormones
associated with the different stages of sleep.
We know that melatonin is a hormone of nighttime
that makes us sleepy.
What about growth hormone release?
When does that occur during sleep?
So growth hormone release happens all day long
and all night long,
but the deep slow-wave sleep that you get
the very first sleep cycle
is when you get a big bolus of growth hormone release
and in men and women equally.
And if you miss that first deep slow-wave sleep period,
you also miss that big bolus of growth hormone release.
And you might get ultimately across the day
just as much overall growth hormone release,
but endocrinologists will tell you that big boluses
do different things than a little bit eked out over time.
So that is when we know there’s also a big push
to synthesize proteins.
So that’s when the protein synthesis part
that builds memories, for example, in our brain
happens in that first cycle of sleep.
So you don’t want to miss that,
especially if you’ve learned something really big
and needs more synaptic space to encode it.
How would somebody miss that first 90 minutes?
So let’s say I normally go to sleep at 10 p.m.
And then from 10 to 11.30 would be this first phase of sleep.
And that’s when the big bolus of growth hormone
would be released.
Does that mean that if I go to sleep instead
at 11.30 or midnight that I miss that first phase of sleep?
Why is it not the case that I get that first phase of sleep
just simply starting later?
It is a beautiful clock that we have in our body
that knows when things should happen.
And it’s every cell in our body has a clock
and all of those clocks are normally synchronized
and the circadian clocks are synchronized.
And so our cells are ready to respond
to that growth hormone release at a particular time.
And if we miss it,
and it’s a time in relation to melatonin also,
so if you miss it,
yeah, you might get some growth hormone release,
but it’s occurring at a time when your clock
has already moved to the next phase.
And so it’s just a clock thing.
Yeah, I don’t think we can overstate the importance
of what you just described.
And to be honest,
despite knowing a bit about the sleep research
and circadian biology,
this is the very first time that I’ve ever heard this,
that if you normally go to sleep at a particular time
and growth hormone is released in that first phase of sleep,
that you can’t simply initiate your sleep bout later
and expect to capture that first phase of sleep.
That’s incredible and I think important.
And as many listeners are probably realizing
also highly actionable.
So what this means is that we should have
fairly consistent bedtimes
in addition to fairly consistent wake times.
Is that right?
Exactly, and in fact,
one of the best markers of good neurological health
when we get older is consistent bedtimes.
I don’t want to backtrack,
but I did write down something that I think
is important for me to resolve or for you to resolve.
So I’m going to ask this,
people that sleep nine hours or more,
perhaps that reflecting an issue,
some underlying issue perhaps,
is being a teenager or an adolescent
and undergoing a stage of development
where there’s a lot of bodily and brain growth,
an exception to that,
because I don’t recall sleeping a ton when I was a teenager.
I had a ton of energy,
but I know a few teenagers and they sleep a lot.
Like they’ll just sleep and sleep and sleep and sleep.
Should we let them sleep and sleep and sleep?
Let them sleep.
Okay, so that’s the one exception.
What about us?
Just like babies.
When you’re developing something in your brain
or the rest of your body,
you really need sleep to help organize that.
I mean, sleep is doing really hard work
in organizing our brains and making it develop right.
And if we deprive ourselves of sleep,
we will actually also just like I said,
we have a daily clock.
We also have a developmental clock
and we can miss a developmental window
if we don’t let ourselves sleep extra like we need to.
What other things inhibit growth hormone release
or other components of this first stage of sleep?
In other words,
if I go to sleep religiously every night at 10 p.m.,
are there things that I perhaps do in the preceding hours
or the preceding day,
like ingest caffeine or alcohol
that can make that first stage of sleep less effective,
even if I’m going to sleep at the same time?
Alcohol definitely will do that
because alcohol is a REM sleep suppressant
and it even suppresses some of that stage two
transition to REM with those sleep spindles.
And those sleep spindles,
we didn’t talk about their function yet,
but they’re really important for moving memories
to our cortex.
It’s a unique time when our hippocampus,
the sort of like the REM of our brains,
writes it to a hard disk,
which is the cortex.
And it’s a unique time when they’re connected.
So if you don’t want to miss that,
you don’t want to miss REM sleep
when it is also a part of the consolidation process
and schema changing process.
And alcohol in there,
before we go to sleep, we’ll do that.
Until we’ve metabolized alcohol
and put it out of our bodies,
it will affect our sleep badly.
It’s probably fair to say no ingestion of alcohol
within the four to six hours preceding sleep,
given the half-life or at all would be better.
But I know some people refuse to go that way.
Maybe a little bit is okay.
I don’t know what the dose response is,
but there are studies out there you can look at.
So we’re still in the first stage of sleep
and I apologize for slowing us down,
but it sounds like it’s an incredibly important
first phase of sleep.
What about the second and third 90 minute blocks of sleep?
Is there anything that makes those unique?
What is their signature,
besides the fact that they come second and third
in the night?
There’s more and more REM sleep,
the later the night we get.
There’s also a change in hormones,
the growth hormone and melatonin levels
are starting to decline,
but other hormones are picking up.
So it is a really different stage
that you also don’t want to shortchange yourself on.
And I think that’s the stage,
many studies are showing that those are the times in sleep
when the most creativity can happen.
That’s when our dreams can incorporate
and put together old and new things together
into a new way.
And our schema are built during that time.
So yeah, we can change our minds best
during those phases of sleep.
Could you elaborate a little bit more on schema?
I don’t think anyone on this podcast
has ever discussed schema.
I’m a little bit familiar with schema
from my courses on psychology,
but it’s been a while.
So maybe if you could just refresh mine
and everyone else’s memory.
It’s still a concept.
How do you define schema?
I think of schema as,
like we have a schema of Christmas, right?
We have all kinds of ideas that we sew together
and call Christmas,
a holiday season in the Northern hemisphere, it’s cold.
We have Santa Claus and reindeer and jingle bells
and even things that are false,
but we normally associate with Christmas presents,
family gathering, when it is,
all of this stuff is sewn together into one.
There’s a thread linking them all.
Linking them all.
And we can just give ourselves a list of words
and none of them contain the word Christmas.
And then ask people later,
give them another list of words
and include the word Christmas.
And they’ll say, oh yeah, that word was there.
Because in their minds,
they brought up that word Christmas
because it’s part of that whole schema.
So that’s what, it’s sort of a related,
a lot of related concepts, I guess.
Can I think about it sort of like
the desktop of my computer
that would scare some people,
but it’s just a ton of folders.
But each of the folder names means something
very clear and specific to me.
And inside of those folders are collections of things
that make sense in terms of how they’re batched.
Is that one way to think about it?
No, that’s a great way to think of it.
And when you’re in REM sleep in the later parts of the night
and that transition to REM,
that’s when your computer of your brain
is opening folders and comparing documents,
seeing if there, is there anything the same?
These two documents look very much the same,
but there’s a little bit of difference
and it can link those conceptually
so that that’s probably one of the origins of creativity
is finding things that are related,
maybe just linked a little bit
and you can find that link and strengthen it
if it makes your schema interesting and different.
Many people, including myself,
tend to wake up maybe once during the middle of the night
to use the restroom.
I’ve tried to drink less fluid before going to sleep.
I’ve heard also that the impulse to urinate,
forgive the topic, but a lot of people deal with this.
So the impulse to urinate is also dictated
by how quickly you drink fluid,
not just the total volume.
So I’ve switched to sipping fluids more slowly
for my last beverage of the day, which seems to help.
But the point here is that I think a lot of people
wake up once in the middle of the night,
oftentimes to use the restroom,
but oftentimes just around 3 a.m.
and might be up for a few minutes,
hopefully not on their phone or viewing any bright light,
which can cause more wakefulness,
but then go back to sleep.
Is there any known detriment
to this middle of the night waking,
or should we consider it a normal feature
for some people’s sleep architecture?
Yeah, I think we shouldn’t worry about it, actually.
I think sleep is really incredibly well
And so really don’t worry about how much you’re sleeping,
as long as you’re not intentionally depriving yourself
of sleep by doing something really rewarding and exciting,
because even that is stressful to your body
and deprives you of a lot of the things we’re talking about.
So don’t worry about it.
It’s absolutely normal to wake up
at least once in the middle of the night
to go to the bathroom.
And as long as you can get back to sleep
in a reasonable amount of time,
or even if it takes you an hour, don’t worry about it,
as long as you have a lifestyle
that allows you to then make up that sleep
either the next morning or the next night,
or going to bed a little earlier.
So if I understand correctly,
there’s a little bit of asymmetry to sleep,
that catching that first phase of sleep,
it’s like you either get it or you don’t,
and you have to get it by going to sleep
essentially the same time each night,
maybe plus or minus 15 minutes or so.
But then if I wake up in the middle of the night
and go back to sleep, I can not catch up,
but I can gather all the sleep that I would have gotten
had I just slept the whole way through the night.
Is that right?
Yeah, yeah, yeah.
And we don’t know actually the answer
to whether or not the sleep in the middle
between that early sleep and the late sleep
is in fact different for another reason,
and whether depriving yourself of sleep
from say one to 2.30 in the morning
is bad in a different way, we don’t know.
Well, I suppose I am the experiment in that case
because I do tend to wake up once per night
and I’ve sort of come to recognize it
as part of my normal sleep architecture.
I don’t obsess over it.
I do notice that when I go back to sleep
and especially toward morning,
that my sleep is incredibly deep.
My dreams are incredibly vivid.
I don’t always remember them,
but what is unique perhaps about the architecture of dreams
and sleep in the, let’s say the last third of the night
or the second half of the night?
Right, yeah, in the second half of the night,
we have longer REM sleep periods,
and those are considered the deepest sleep,
even though slow wave sleep,
big slow wave is considered deep, it is deep.
Yeah, they call slow wave sleep deep sleep
and REM sleep rapid eye movement,
but now you’re telling me that REM sleep
is actually the deeper sleep.
Okay, there needs to be a new nomenclature
of sleep researchers.
Yeah, I know, you really shouldn’t call it deep or not.
No, no, please.
The reason why you call slow wave sleep deep sleep
is because it’s difficult to arouse people
out of that state.
And when you do arouse them out of that state,
they’re most often confused
and just want to go back into sleep
and can go back pretty easily.
If you arouse someone out of REM sleep,
they’re more likely to report something
that was really kind of almost like wakefulness.
It was so vivid.
But in fact, if you give someone
a non-threatening kind of stimulation,
like somebody dropping keys
or a ping or something like that,
instead of waking,
that same volume will wake someone up
out of non-REM sleep,
but out of REM sleep and instead lengthen
the amount of time or make it even more dense,
your rapid eye movement’s more dense.
And often people will incorporate
that sound into their dreams.
So the body and brain are somehow conscious
of the sound, and I’ve heard also smells
can even make it into our dreams in REM sleep,
but that it doesn’t arouse us from sleep.
It doesn’t arouse us as often, yeah.
And maybe one of the reasons why REM sleep is deeper
is especially in adults and older people,
that deep slow wave sleep goes away.
So it’s not as deep, it’s not as big.
The slow waves aren’t as large,
which is probably problematic, but we’re not sure.
And so then REM sleep becomes the deepest stage.
Actually in children, it’s kind of a toss up
because it’s really hard to wake them up
out of that deep slow wave sleep.
And in fact, fire alarms don’t wake them up,
even really loud fire alarms out of that state of sleep.
So that’s why they’re trying to change fire alarms
so that instead of something
that the kids don’t associate with anything,
like the rrr, rrr, whatever, they don’t associate with,
it says their name or something else
that may be less loud, but more salient to them,
and will wake them up.
I don’t know, having carried sleeping children
in from the car, I don’t know that I want children
to start waking up from sleep,
because that’s one of the best things when you get home
and the kids are asleep in the backseat,
you can literally throw them over your shoulder,
gently, of course, and put them to sleep,
and they are completely out.
Yeah, it’s wonderful.
It is wonderful.
One of nature’s gifts.
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So this enhanced volume or proportion
of rapid eye movement sleep in the second half of the night
relates to more elaborate dreams.
We are paralyzed during REM sleep, correct?
Yes, normally paralyzed, and that’s really good
because that’s the time
when we’re actively dreaming storyline dreams
and we could hurt ourselves.
We’re actually really cut off from the outside world
in terms of responding to, say, this table
or a window or a door.
And so different from sleepwalking,
which is out of slow-wave sleep,
and out of slow-wave sleep, that sleepwalking
is a mixture between sleep and wakefulness.
So you actually will respond to the door.
You can cook a full meal, drive your car
while you’re in deep slow-wave sleep.
It’s scary because you never know what you’re going to do.
You don’t have voluntary control over it.
You have no conscious control over it,
but you can actually safely navigate some situations
in sleepwalking and actually have a conversation,
although it may not make much sense
when you’re sleep-talking.
In REM sleep, you’re not processing the outside world.
And instead, when you’re acting out your dreams,
you could be doing things like walking
through a plate glass window
or falling off of, down the stairs, things like that.
So you really want your muscles
to be inactivated during REM sleep.
Otherwise you will act out those dreams
and really hurt yourself or your bed partner.
What about sleep-talking or talking in sleep?
I don’t know how many relationships
have been saved by sleep-talking,
but I’m guessing a few have been destroyed.
And I’m guessing that talking in sleep could have meaning
or perhaps has no meaning,
just as dreams could have meaning or no meaning,
as we recall them.
Yeah, do not take sleep-talking seriously.
No matter what people say,
it doesn’t necessarily reflect truth.
So it’s not like you’re being more truthful
when you’re sleep-talking.
You just saved a number of relationships.
I hope so.
I’m not directing this at anyone in particular,
but I guarantee you just did.
So as people start to approach morning
or the time when they normally would wake up,
I’ve heard that it’s important to, if possible,
complete one of these 90-minute cycles prior to waking up.
That is, if you set your alarm
for halfway through one of these 90-minute cycles
that come late in the night of sleep,
that it can lead to rather groggy patterns of waking.
So I’ll just ask you directly, do you use an alarm clock?
I do not.
Thankfully, I’m in a line of work
that doesn’t require me normally
to do anything at any particular time.
I do it when I do it, unless I have to catch a plane,
and then I always set my alarm, just in case.
Well, as a fellow academic, I can tell you
there are plenty of punishing features
about being an academic scientist
that offset the fact that you don’t have
to use an alarm clock,
but it is nice that you can often set your own schedule.
So would you recommend that, if possible,
that people not use an alarm clock?
If you can just listen to your body and wake up
when you need to wake up, that would be great.
But one of the reasons why we have such a grogginess,
it’s called sleep inertia,
when we wake up out of the wrong state,
which is deep slow-wave sleep,
is because I liken it to like a washing machine cycle.
This 90-minute cycle is like a washing machine cycle.
And the first part is to add water, right?
And then your clothes are soaking wet.
You don’t wanna open the washing machine
and try and function, put them on and wear them around
while they’re soaking wet and full of soap.
So you’d have to wait until the cycle is through
before you can, well, actually,
let’s put it in the dryer too,
before you wanna wear them.
So yeah, you can function.
It just takes a little while for those clothes,
that brain to dry out so you can actually function well.
But it’s better to wait through the whole cycle is complete.
And so that’s why you want to set
that 90-minute alarm clock.
And again, that’s around 90 minutes
because the first stage of sleep,
the first cycle of sleep is actually a little longer,
more like 105, 110 minutes,
but then the second ones and third ones,
they get sort of shorter and shorter as the night goes on.
And in the last few cycles,
you’re just doing the N2 REM sleep cycle,
which takes less time.
And if you wake up out of REM sleep,
there’s usually no problem cognitively.
You’re good to go.
Are you a fan of sleep trackers?
Do you use one?
I have one on.
I don’t live my life by them
because they are,
the best ones right now are about 70% effective
at staging your sleep.
So 70%, it’s okay.
It’s okay, but take it with a grain of salt
is what I’m saying.
Yeah, I’ve tried various ones
and I compare the mattress-based one to a,
I actually wear it on my ankle instead of my wrist,
but, and I do find it informative,
but a colleague of mine at Stanford,
Ali Crum, who works on mindset and belief effects,
talked to me about a study they did
where people often will bias
their sense of daytime wakefulness
based on their sleep score
more than their subjective score.
In other words, if they were told
they got a poor night’s sleep,
even if they got a great night’s sleep
and this was of course measured in the sleep lab,
so they were able to compare,
people report feeling more groggy.
And the opposite is also true,
that if it says 100% or 90% on your sleep score,
then people go, oh, I feel great,
even though they might not have slept well.
So this speaks to the,
I don’t wanna say placebo effect,
but the sort of belief effects
that are woven in with a score.
Yeah, that’s right.
So it seems to me that combining
subjective and objective data is probably best.
Yeah, and I do believe
that you should trust your own physiology
and the way that your body is telling you to feel,
because in fact, it used to be
that people with insomnia were often not believed
because you’d put them in a sleep lab
and they look like they slept great
and you wake them up in the morning,
they say, oh, I didn’t sleep very well at all.
And that’s because probably we just came out
with a paper that shows that subcortical structures
can be in a completely different sleep state
than cortical structures,
which is what we measure in the sleep lab,
what the cortex is doing.
So it might be that people who say,
I did not sleep all night long,
even though the cortex is saying,
oh no, you had great sleep,
was because they’re monitoring their subcortical
hypothalamus, hippocampus, thalamus,
other structures that the sleep lab just can’t access
unless you have depth electrodes,
which nobody really wants.
Right, because that requires holes in the skull
Wow, so does that mean that the last 50 plus years
of sleep science, it’s potentially flawed in some way
because they’re only recording from,
I guess this would be the analogy would be,
it’s like recording from the surface of the ocean
as opposed to the depth of the ocean.
And trying to ascertain the life moving down deep
in the depth of the ocean.
Brace yourselves, colleagues at Stanford Sleep Lab
and elsewhere, but please just tell us,
because I think scientists want to know the truth.
Yeah, I mean, it’s not for nothing
that you want to know what the cortex is doing.
I mean, the cortex is really important for a lot of things,
but it doesn’t necessarily tell you
what a lot of other really important parts of the brain
are doing in terms of sleep.
And, but there’s hope because in fact, it would be great.
I think that’s possible from the paper, if you look at it,
it’s in PNAS this year,
that you could detect subtle changes in the cortical EEG
that might be able to tell you
what the subcortical structures are doing.
Things like the absolute power in that sleep spindle band,
that sigma band would change
if the hippocampus is in REM sleep
and the cortex is in that sleep spindle state
and vice versa.
So there is some hope that we can gain
from people with depth electrodes
or animals with depth electrodes
that we could backwards machine learn
what the cortex might be able to tell us
about subcortical structures from the cortical EEG, so.
Interesting, this is going to be a stimulus.
Yes, stay tuned.
It’s going to be a stimulus
for development of new technology,
which is always going to assist in scientific discovery.
One more thing I wanted to ask about
the architecture of the night’s sleep
in terms of early part of the night.
Earlier, you mentioned the washout of debris
and the so-called glymphatic system,
I think is what you’re referring to.
Could you tell us a little bit more about the washout
that occurs in the brain during sleep,
what that is and what roles it’s thought to serve
and perhaps if there are any ways to ensure that it happens
or to ensure that it doesn’t happen
and obviously we want this to happen.
All right, great question.
We talked about the circadian clock
and how certain things happen at certain times.
Well, one of the things that happens when we’re awake
and talking to each other
is that there’s a lot of plasticity.
There’s something that I’m learning from you today
and you’re learning from me
and that changes our synapses
and it changes the way our proteins
are going to be folded and changed during sleep.
This process actually uses a lot of ATP,
the power structure, the fuel of the brain
and it unfolds also proteins while we’re doing this,
while we’re using them
and so during that first part of the night,
when we first fall asleep in the first 20 minutes or so,
we’re building that adenosine back into ATP
and that’s probably why power naps are called power naps
because we’re actually rebuilding the power
and then we’re also cleaning out
through the deep slow waves of sleep,
we’re cleaning out all those misfolded proteins,
unfolded proteins and other things that get broken down
and need to be rebuilt when we’re asleep
because of its use during wakefulness.
So I liken that to having a big party during wakefulness
and you need all those party goers to leave
in order to do the cleanup
and so what I think the mechanism is
and this is still something to be tested
is actually slow waves themselves,
which is bad news for us as we get older
and those slow waves get smaller
and slowly sleep goes away.
So what happens when a neuron is firing
is that it expands, the membrane expands a little bit,
it becomes more translucent, that’s how we know,
one of the ways we know that neurons expand when they fire
and so every action potential,
the membrane expands a little bit
as sodium brings water into the cell
and then when they’re silent, they contract
and so in during slow waves,
the cool thing is that the reason why you can measure them
is that all the neurons at the same time,
not all of them but a good portion of them
are firing at the same time and silent at the same time
and so you think about that as contracting
and expanding all at the same time,
it’s kind of like a bilge pump of the brain
so that can pump out,
glia are also really important for this
in terms of cleaning up debris
and transferring it to where it needs to go
so I think of it actually as a bilge pump,
cleaning out our brain.
Interesting, I’ve heard about the glymphatic system
and the lymphatic washout,
I had never thought about the mechanical aspects
of it before.
I always thought that for some reason
that now it’s obvious to me
that there had to be something mechanical
but only now that you’ve educated me about this,
I thought that for some reason,
the cerebral spinal fluid just starts washing through
but here you’re talking about literally an expansion
and a contraction of the neurons in unison
and pushing the fluid through,
cleaning out any misfolded proteins
or debris that might occur
on the basis of these metabolic pathways
and the consequence of that is to what?
To leave the brain in a state of more pristine action
for the next day, is that right?
Yeah, you think of it again like a party
and if you don’t clean up after that party
and you try and hold another one the next day,
it’s gonna get more clogged,
people have a harder time moving around
and enjoying themselves
and if that builds up day after day,
it’s gonna be cognition,
that would be the party goers moving around,
becomes hard, yeah.
And so this build pump that you describe
is associated with the big slow waves of deep,
well, of slow wave sleep.
So this is gonna occur more or less
in the first third of the night, is that right?
And are there things that inhibit this process
and are there things that facilitate this process?
Yeah, so, well, one thing to inhibit is not to get it,
Right, and here too, sorry to interrupt,
but, and is this similar to the case with growth hormone
where if you go to sleep later than you would normally,
you miss the washout, you don’t delay it,
you miss the washout.
That’s right, so if you go to sleep
at one or two in the morning,
your sleep is still gonna be dominated
by N2 and REM sleep, not by slow wave sleep.
So you need to get that first bit of sleep.
Would a caveat to that be,
if somebody normally goes to sleep at one or 2 a.m.
and wakes up at 10 a.m.,
if that’s their normal sleep cycle-
Yeah, that should be okay.
It should be okay.
You would probably wanna do,
somebody would wanna do a sleep study
with people who do that normally
and see if also the melatonin releases later
and the corticosterone rise
that happens normally in the morning
and that also happens later.
So if everything shifted, good.
Okay, yeah, there are a few studies I’ve come across
that really do argue for the fact
that waking up circa sunrise,
that doesn’t mean at sunrise,
but within an hour or two, maybe three hours of sunrise,
and going to sleep within four hours after sunset or so
is actually better for the health of all human beings
than is being a night owl.
There’s almost like a night owl posse out there,
especially on social media.
They get very upset when you say
that you should see morning sunlight,
that after 10 a.m. you kind of miss the boat,
and they get very upset
because I think there are about 20 or 30% of people,
perhaps, who really feel like they function better
staying up late and waking up late
and they function much less well waking up early
and going to bed early.
But the data on health metrics
suggests that, sorry, night owls, that they are wrong.
Yeah, sorry me, because I’m a night owl.
Oh boy, okay, well then I’m apologizing directly.
And here, I’m not a really early morning person.
I’m kind of more typical.
If I wake up naturally around 6.30,
somewhere between 6.30 and 7.30 a.m.,
go to sleep somewhere between 10 and 11 p.m.
These are averages.
But I do notice that when I force myself
to get up a little earlier and go to sleep a little earlier,
that my mood and alertness
and just overall productivity is much higher.
And there could be other variables there, too.
Yeah, you’re absolutely right.
I’m a night owl.
I love staying up late at night, writing grants,
writing papers, watching movies, whatever it is, I love it.
But I, like you, and like every human being on Earth,
do better if I go to bed earlier and wake up earlier.
So one good thing for night owls is to have a child,
because they will wake you up.
Their circadian rhythms are so strong, they will wake up.
And even if you deprive them of sleep
in the first half of the night,
they will still wake up like clockwork
because their circadian rhythms are so strong at 6.00 a.m.
And so what you’ve,
you haven’t done anything good for your kid.
You haven’t moved their cycle to later
and be more in line with yours.
In fact, you’ve just sleep deprived them
and made them miss a window
and made them cranky the next day
and made your life more miserable.
So go to bed soon after your kids go to bed
and wake up with them.
That’s the way to do it.
Great, the child alarm clock,
another reason I have children.
I got a dog, a puppy,
and then that became a dog specifically,
well, for many reasons.
But one reason was I wanted to be one of those early morning
Raj, you know, 5.30 a.m. every morning.
But I ended up getting a bulldog that would literally sleep
16 hours if he could.
A nuclear bomb could go off and he wouldn’t wake up.
But what I started to learn was that bulldogs
actually have sleep apnea.
As far as I know,
they’re the only species that has a genetically,
they’re essentially an inbred sleep defect.
And so I actually don’t encourage people to get bulldogs
because it’s kind of a cruel breed.
They suffer a lot in that body that they’re born into.
Anyway, a dog can accomplish some of this,
but get the breed of dog that is going to wake up early.
So in other words, don’t get a bulldog or a mastiff.
Well, you know, interestingly all predatory animals
like dogs and cats and lions and us,
well, more dogs, cats, and lions than us,
wills can sleep, you know, 16 hours a day.
Ferrets are predatory.
They can sleep-
I had a pet ferret.
And sadly, I also used to work on ferrets,
publish a number of papers.
Yeah, and great because you can study development.
It’s really cool because they’re born very altricial
like we are with brains that are not very well developed.
And so you can see what happens through development
and how important these different phases
of development really are.
Yeah, maybe we’re not as much predators as we think
because in fact, our sleep is somewhere between the prey
and the predators in terms of the amount of sleep
that we usually need a night.
But those predators can sleep 16 hours,
napping all day long,
and they’re more crepuscular perhaps like their prey are
So dawn and dusk active?
Yeah, dawn and dusk active.
Yeah, but anyway, yes.
Children and dogs.
Actually, there was a poll done
by the National Sleep Foundation
to see what the number one thing is
that wakes people up at night.
And number two is going to the bathroom.
Number three is children because, you know,
when your children are young,
but that only lasts a few years
that they’ll wake you up when they’re babies.
But the number one thing is pets
and pets needing to go out
or cats wanting to curl up with you or whatever it is,
pets needs will wake you up more
in the middle of the night than anything else.
Another reason to not get a nocturnal pet.
People who get hamsters pretty quickly realize
that they are nocturnal
and they want to run on their wheel around.
Yeah, you got to put them in the living room
away from where you sleep.
I vote fish tank, folks.
Freshwater fish tank.
There are all sorts of reasons to not get a saltwater tank.
Freshwater fish tank or a child.
I appreciate that vote.
And I appreciate you mentioning ferrets.
And by the way, folks, they are carnivores.
They are not rodents and they are,
they have very elaborate brain structures.
They’re very smart in the same family
as the honey badgers and the other mustelids.
Anyway, I shouldn’t geek out too much on the mustelids
or else I’ll take the remainder of all our time.
I’d love for you to tell us about REM sleep
and the sleep later in the night
as it relates to dreams and emotionality.
And this is probably the appropriate time
for you to introduce us to this incredible structure
in the brain, which is the locus coeruleus,
a difficult structure to spell,
but a beautifully named structure.
I find locus coeruleus to be just fascinating.
And I know a small fraction of what it does,
and I’m hoping you’re going to educate me
and our audience about more about what it does
and hopefully tell us a little bit about its relationship
to epinephrine, AKA adrenaline.
Yeah, I am so glad you brought this up
because I can totally geek out on the locus coeruleus.
Locus meaning spot or place and coeruleus meaning blue.
So you could just call it the blue spot.
That’s the easiest.
Every animal with a brain has a blue spot.
And yeah, and I mean every animal with a brain
because of course there are animals with nervous systems
that are not centralized like jellyfish.
But anyway, we’re digressing there.
So the locus coeruleus is filled with neurons
that have in them norepinephrine,
which is the brain’s version of epinephrine or adrenaline.
It’s also called noradrenaline.
And what it does is it,
just like adrenaline in the rest of our bodies,
it helps prime us to respond to our environment.
So when locus coeruleus neurons fire and fire in a burst,
we can switch our attention and they will fire in a burst
if, for example, a loud noise happens
in the middle of your concentrating on something.
So you can, it helps, it fires
and it helps you switch your attention to that thing
and then learn quickly from it.
So it’s really important in a stress response.
It helps us do quick one-trial learning.
And then tonic activity during the day
when you’re just, you know, doing normal,
going about your normal concentration kind of activities
is really good for sustained attention.
It works with the cholinergic system of our basal forebrain,
which is really important for learning and memory also
to help us learn about things and put things together.
But just tonic levels are signature
of wakefulness and alertness.
So too much is panic with locus coeruleus activity.
A burst is switching attention
and then tonic levels are sustained constant attention.
And then when we go to sleep, the locus coeruleus slows
and goes from about on average two Hertz
to about one Hertz, one cycle per second tonically.
And then when we go into REM sleep,
it’s the only time when it shuts off completely.
And it appears that that complete silence
is really, really important for a number of things.
And the main thing that I think it’s important for
is the ability to erase and break down synapses
that are no longer working for us.
So they encode things that are false now,
or they are encoding things that we learned
in the novelty encoding pathway of our brain
that have now been consolidated to other pathways.
And so we need to now erase them
from the novelty encoding pathway.
And that is really, really important
for being able to continue to learn things
all of our lives.
So like erasing that REM or that, I don’t know,
what do you call those discs
that you stick in the computers?
No, thumb drives.
Yeah, erasing your thumb drives.
That thumb drive is what you carry around all day long.
And then during sleep, you write that thumb drive
to the cortex, to the long-term memory structures,
and you need to refresh that thumb drive.
And that’s what happens during REM sleep
when the locus coeruleus is off.
Because whenever it’s on and neuroadrenaline is there,
it helps us to put things together.
It helps us to learn and strengthen synapses,
but it does not allow us to actually weaken synapses
that are also a really important part
for life, important part of lifelong learning.
Yeah, there’s so much more I could say about that.
Yeah, locus coeruleus sounds fascinating.
So it’s connected to the basal four brain
The neurons in locus coeruleus,
if I’m not mistaken, release norepinephrine,
perhaps epinephrine as well?
Well, no, the brain’s version of epinephrine
The other thing it also,
the precursor to norepinephrine is dopamine.
And so the source of dopamine in the hippocampus
seems to be the locus coeruleus,
and it’s still a mystery as under what conditions
the locus coeruleus also releases dopamine,
but it’s really important when we’re learning something new
to also release dopamine
or to at least activate the dopaminergic receptors
in our hippocampus.
So yeah, so dopamine, norepinephrine,
and then there’s also galanin,
which is important for releasing when we’re stressed,
and it helps also without rapid learning.
It works in concert with norepinephrine
and in doing what it needs to do to strengthen synapses
so that we learn really quickly.
I love that there are multiple molecules involved
because that signals us to a principle,
which is that even if people can’t remember all the names,
that rarely in biology is something handled
by just one molecule or pathway,
that redundancy is the rule
because signaling attention to specific events
is so important.
So I’m gonna use that as a just-so story.
I always say, you know,
I wasn’t consulted at the design phase,
but it makes sense to me as to why redundancy
would exist in the system.
Absolutely, and in fact,
when we form hypotheses about the brain,
we’re always wrong.
And the reason why we’re always wrong
is because it’s more complicated than we’d like to think.
And because in our brains, when we’re forming hypotheses,
we fail to account for all of the factors that are involved,
you know, the glia, the neuropeptides, the neurotransmitters,
the physical structure of synapses.
And so when I was going through grad school 35 years ago,
the dogma was that every neuron
contains one neurotransmitter
and releases one neurotransmitter.
And you had excitatory neurotransmitters
and inhibitory neurotransmitters
and neuromodulatory neurotransmitters,
but that’s as complicated as God.
And then we started talking about neuropeptides
and people said, oh no, please don’t complicate it.
And then we started talking about how neurons
contain both neuropeptides and neurotransmitters
and maybe more than one neurotransmitter.
Maybe even hormones too.
And hormones and oh Lord, you know,
it’s just so complicated,
but I gotta admit that’s why it works, right?
And every time the brain teaches us
something new about itself that we didn’t hypothesize,
we say, oh, of course,
that wouldn’t work if the way I hypothesized it with it,
you know, we actually need redundancy.
We need all of these systems to work together.
Yeah, it’s daunting sometimes,
but it also ensures many, many careers in science
and neuroscience in particular.
So note that aspiring scientists,
there’s plenty of room for discovery.
Do you want me to talk about norepinephrine and emotion?
Yes, well, what I’d love for you to tell us about is,
you know, what role this lack of norepinephrine release
during rapid eye movement sleep is thought to achieve.
And maybe you could also review some of your work
describing conditions under which norepinephrine invades.
Yeah, invades sleep.
Rapid eye movement sleep and other patterns of sleep
and how that can be detrimental.
Yeah, so a lot of this is hypothetical,
but based on a lot of good evidence
that we’re sewing together into a schema
from which these hypotheses come,
so a model schema from which the hypotheses come.
But one thing that happens to people
with post-traumatic stress disorder
is that there is a lot of evidence
that the locus surrealis doesn’t stop firing in REM sleep.
So whereas their levels of norepinephrine
might be similar to people without PTSD during the day
and even during the first part of the night,
during the wee hours of the morning
and when you measure norepinephrine levels
from metabolites in the blood or the cerebrospinal fluid,
you see that people with PTSD,
it’s during the wee hours of the morning
when you have the most REM sleep that they have,
their norepinephrine levels differentiate most
from those that don’t have PTSD.
And so that’s evidence that the locus surrealis
is not shutting down during REM sleep like it should.
Other evidence is heart rate variability.
When our locus surrealis is firing,
our heart rates are generally a little higher
and they don’t vary as much as they do
when the locus surrealis is not firing.
So during slow-wave sleep,
normally have this big juicy variability in heart rate
with every breath in and breath out
because our noradrenergic levels,
our norepinephrine levels are lower.
During REM sleep, that goes away entirely
and our heart rate is dominated by parasympathetic
rather than sympathetic activity
and also what our brain is driving,
what are we dreaming about, for example,
if we’re dreaming we’re running,
our heart rates will go up.
But norepinephrine levels still should be low or off.
So people with PTSD, that noradrenergic,
we’re studying these in rats too,
is it true that our locus surrealis doesn’t shut off
when we have post-traumatic stress disorder
and the preliminary evidence is yes,
it’s true that it doesn’t shut off.
So what that would do is norepinephrine
would act at synapses to prevent that weakening
that you really need, for example,
of novelty encoding structures
and it keeps memories in that novelty encoding structure
even once it’s consolidated to the rest of the brain.
In the hippocampus, which is important
for remembering things throughout our lives
and it’s that thumb drive,
we need it to be erased so that we can learn new things
once it’s been consolidated
to the hard drive of our cortex.
And so if we’re not able to do that,
we fill up that RAM really quickly
or that thumb drive really quickly
and we’re not able to learn new things.
So for example, after a trauma,
I talked about the locus surrealis
responding in stressful situations, that’s great,
it’s very adaptive, but then you need it to stop.
Once you’ve learned what you need to learn from it
and you wanna go to sleep,
you need the locus surrealis to calm down
and during REM sleep, you want it to stop
because then when you’ve consolidated
that traumatic memory to the cortex,
you need to erase it from the novelty encoding structures,
for example, in the hippocampus,
so that then when you’re in the context of safety,
you can learn those new things, those new contexts
and stop responding to those same stimuli
as though you’re in that original situation.
So if you’re not able to erase that thumb drive,
you will always feel like that trauma happened
that same day, like earlier that same day
and respond as you would to a recent trauma,
which is with beating heart and all of that.
So even memories that are years past,
if you’re never able to downscale that novelty
encoding structure and purge it from that traumatic memory,
it will stay fresh and new and then become maladaptive.
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What approaches are you aware of
that can turn down the output of locus coeruleus
during these phases of sleep?
And for that matter, what things can cause ramping up
of locus coeruleus during this phase of sleep?
We’ve had a couple podcast episodes, solo episodes,
and with guests talking about trauma.
We had Dr. Paul Conti, who’s a Stanford-trained,
Harvard-trained psychiatrist who talked a lot about trauma,
wrote an excellent book on trauma,
and certainly sleep was emphasized as a key thing,
like get enough sleep, but here you’re saying
even if somebody with trauma gets enough sleep,
if locus coeruleus is hyperactive during sleep,
those traumas are gonna persist,
and most of the trauma treatments that I’m aware of
are everything ranging from cognitive behavioral therapy,
talk therapy, drug therapy, EMDR, hypnosis.
Nowadays, there’s a lot of interest and attention
on clinical studies on exploring psychedelics,
high-dose psilocybin, and MDMA,
so it’s a vast landscape, none of which, as far as I know,
is really focused on sleep specifically.
No, they’re not, and they should be,
because actually, psychedelics is a sleep-like state,
and it’s a REM sleep-like state,
although, of course, there are some major differences,
so yeah, so much to talk about here.
So antidepressants are often noradrenergic
or serotonergic reuptake inhibitors,
so they leave norepinephrine, actually,
out there in the synapses,
and what that does is it inhibits REM sleep,
and if you’re able to get REM sleep,
it would probably be REM sleep
with some noradrenergic activity,
so actually, I think, anyway, I’m not a physician,
that antidepressants are counter-indicated.
You don’t want to take them if you’ve experienced a trauma
and you’re experiencing PTSD,
because if anything, it’s going to make it worse
or at least prevent the type of adaptive REM sleep
that you really need in order to resolve those emotions
and move on.
Is that statement specific to antidepressants
that tickle the noradrenergic pathway?
So the one that comes to mind is, I can never pronounce it,
bupropyron, which is, I think the brand name is Welbutrin.
It’s a dopaminergic and noradrenergic agonist,
that’s the net effect, as opposed to the Prozac,
Zoloft variety, which are SSRIs.
Yes, yes, but SSRIs themselves also are problematic
because we didn’t talk about it yet,
but the dorsal raphe nucleus, which produces serotonin,
which the specific serotonin reuptake inhibitors
block from being reuptaken,
leaves too much serotonin out there.
And what serotonin also is, another neurotransmitter
that’s down-regulated during REM sleep,
that’s specifically off during REM sleep.
And what serotonin does is it weights all of our cognition
to being able to recognize novelty again.
So it sort of weights our brain away
from a sense of familiarity and toward novelty.
And it might be one reason
why it’s an effective antidepressant,
because it makes the world feel fresh and new again, right?
But when you have too much,
you’re holding a novel traumatic memory
in your novelty encoding structure too strongly already,
you don’t want to, again, weight things toward novelty.
You need that absence of serotonin also
to help you get that sense of familiarity
and to start erasing the novelty encoding structures.
So you need both to be absent.
It’s really interesting.
We hear a lot about serotonin,
and it’s not often discussed in terms of its features
related to novelty enough, I think.
And what you just described cues me to something
that Dr. Paul Conti and others have said
in terms of trauma, and here I’m paraphrasing,
so my apologies to them for not getting this exactly right,
that an effective treatment for trauma
does not erase the traumatic memory,
but it causes a transition
of what once was disturbing and invasive and maladaptive
to eventually just become kind of a boring old story
that has kind of a fuzzy texture to it,
as opposed to this kind of sharp, high friction texture
that invades our thinking
and obviously our sleeping states as well.
So again, and I appreciate the disclaimer,
the caveats around not being a clinician, et cetera,
but I do think that there’s a lot of interest now
in whether or not antidepressants
are effective for trauma or not.
And I think these aspects of neuromodulation
as they relate to, let’s call it erasing traumas
or changing the emotional load of traumas during sleep
is something important to take note.
We also have a lot of clinicians
that listen to this podcast,
so they should also take note, please.
So if I want to reduce the amount of norepinephrine
released from locus coeruleus
during rapid eye movement sleep
to eliminate the troubling or maybe even traumatic memories
and allow late stages of sleep each night
to have their maximum positive effect,
is there anything that I can do besides avoiding traumas,
avoiding serotonergic or neuroadrenergic compounds?
Well, I would also avoid anything
just prior to going to sleep that might excite those systems.
So a lot of novelty, a lot of exciting,
stress-inducing video games.
Try and enter sleep with as much calm as you can.
So maybe deep breathing exercises.
That’s a beautiful way to calm your sympathetic
fight or flight system is deep breathing.
And we haven’t been able to test this with rats
because we can’t ask them to do a deep breathing exercise.
There might be a way we can do that,
but I haven’t found out or figured it out yet.
But if there’s a way you can make your sympathetic system,
nervous system calm down before you go to sleep,
might free for you meditation or deep breathing exercises.
It might be for some, a warm bath or a comforting book.
Nothing too exciting, but also nothing too boring, perhaps.
Just something right in the middle,
which makes you feel happy and calm is what you should do.
And if you instead go to sleep while you’re anxious
or you’re hyped up,
then your sleep could become maladaptive.
Another thing that happens in rats that we have yet to know,
if it happens in women,
is that female rats have three phases of their estrous cycle
that their locus realis doesn’t seem to calm down
during REM sleep as much.
And we don’t know why,
but during the high estrogen phases of their estrous cycle,
the locus realis shuts down just like it does in male rats.
But in the other three phases, it doesn’t.
So one thing that might work,
and in fact, there are a few studies that show it,
it could work really well,
is giving women after a trauma event
something that contains estrogen,
because estrogen somehow is protective against PTSD.
And they know that through retrospective studies
where they gave women an emergency room,
either a pill with estrogen or without,
and those that had the pill with estrogen in it
were much less likely to get PTSD from that trauma
as measured a year later
than those that had the pill without.
So there are some really good studies by Bronwyn Graham,
she’s out of Australia,
to really hone in on how much estrogen do you need
and also testosterone, just so you know,
gets converted to estrogen in the brain.
So testosterone also can be protective
because it gets converted to estrogen.
But there’s something about estrogen
that’s really helpful and protective
about that from the high locus realis firing.
And this is, again, preliminary data
that we don’t have full,
we don’t have all the answers yet,
and we are looking into it actively right now,
but it’s really important.
The other thing about women is that we are
two to four times more susceptible
to anxiety-related mental health disorders,
including post-traumatic stress disorder.
So if we could figure out what’s happening
to the locus realis during sleep in women,
and then figure out a way to normalize that
so the locus realis is silent
when it needs to be silent,
I think we could go a long way
in helping women be more resilient
to stress-related disorders.
What are some other sex differences
as they relate to sleep?
Yeah, yeah, that’s a really good question.
There have been very few studies, unfortunately,
of women in sleep, women in estrous cycle
or menstrual cycle in sleep.
But what we have found,
which actually largely replicated the study in 1960,
is that women, or females, rather,
at high estrogen, high hormonal phases
of their estrous cycle or menstrual cycle
sleep a lot less, but that sleep is more efficient.
So that sleep is more dense in those sleep spindles,
which I haven’t gone into what they might do,
except this connection between the hippocampus and cortex,
but those sleep spindles are more dense
and more coherent across the brain areas.
The theta cycle, which is five to 10 hertz
in the hippocampus, important for one-year learning
and also important during REM sleep,
is also bigger and juicier during the high hormonal phases.
So even though there’s less sleep,
it’s more efficient and better.
So all of that efficiency seems to be reduced
in those other hormonal phases.
So even though you might sleep a little more,
you might need more sleep, in fact,
in order to accomplish the same thing
that you can get with that short,
very efficient sleep of high hormonal phases.
I think there’s a growing trend,
at least among NIH-funded grants,
to require that, as they refer to it in the grants,
biological sex as a variable.
And here we’re not talking about sex, the verb,
although I’m sure there’s studies about that too,
but biological sex is a variable
because there is a dearth of studies
exploring sex differences in most everything.
There are all sorts of reasons for that,
but more importantly, fortunately, the trend is shifting.
And even when you study males versus females,
a lot of people just include females in their studies,
but then don’t track the estrous cycle or menstrual cycle.
And hormones have huge effects on our behavior.
I mean, just think of when you said sex,
before hormones come in, we’re not interested in it.
And suddenly, that’s kind of a main driver of behaviors.
Hormones can definitely change who we are and what we do.
So we should be studying hormones, not just sex.
I always say that puberty
is perhaps the most massive transformation
and rate of aging that any of us go through
in a short amount of time.
An individual, their cognition changes,
their worldview changes, and that’s largely hormonal driven
and obviously neural architectures change too.
I’m very happy that you mentioned
I’m trying to get into calmer states prior to sleep
and some ways to do that.
I’m a big fan, and I’ve talked a lot before on this podcast
about things like yoga nidra,
which is a non-movement based practice,
sometimes called non-sleep depressed,
where people actually take some time each day
to practice how to go into a more parasympathetic,
aka relaxed state deliberately,
because it’s a bit of a skill.
Yeah, and there’s some good data really,
mostly out of a laboratory in Scandinavia
showing huge increases in nigrostriatal dopamine
when people basically engage in a practice
of deliberate non-movement,
and that the brain actually enters states
of a very shallow sleep.
So it’s sort of nap-ish,
but the idea is to actually stay awake, but motionless.
And it does seem to restore
a certain number of features of neurochemistry,
but perhaps more importantly, it teaches people to relax,
which is something that most people are not very good at.
But in any event, and people who listen to this podcast
have heard me say this over and over again,
so I sound like a broken record,
but this practice as a zero cost practice
that doesn’t require any pharmacology
does seem to really enhance people’s ability
to fall asleep more quickly
and to fall back asleep
if they wake up in the middle of the night.
So in any event, another plug for NSDR, yoga nidra.
Well, I just also want to add to that.
That’s one of the reasons why insomnia is so insidious
is because when people feel like
they haven’t gotten enough sleep
and they’re not getting enough sleep
and they become anxious about getting enough sleep,
and then you’re anxious before going to sleep,
like I’m not going to fall asleep,
it’s going to be 45 minutes in,
and then that’s a positive feedback loop.
So you need to break that loop,
say, okay, my body’s going to get as much sleep as it needs,
I needn’t worry about it,
and then practice this relaxation to say,
hey, it’s all okay, it’s going to be all right,
and then concentrate on things that relax you,
whether it’s concentrating or not concentrating,
whatever it is.
You mentioned yoga nidra,
and that reminded me of transcendental meditation,
which is something that also hasn’t been studied well,
largely because we can’t ask non-human animals to do it,
and so we don’t know what’s happening
with our neurochemistry and our brain activity
in a deep and meaningful way,
but one thing that has been shown
and those that can do it really well
is that that theta activity that I said
happens when you’re learning something
or when you’re in REM sleep,
it’s well-established and increases
during the transcendental meditation,
so it might be that some states of meditation
could in some ways replace or mimic some functions
of, for example, REM sleep,
but again, we don’t know if all the neurochemistry is right
to do, for example, the thing that I was talking about,
which is erasing the novelty
and coding structures of the brain.
That needs an absence of norepinephrine and serotonin,
which we don’t know if that goes away
with transcendental meditation,
we just don’t know the answer to that yet.
Yeah, the studies on yoga nidra and sleep replacement
are kind of interesting.
It does seem to be the case
that nothing can really replace sleep except sleep,
but that if one is sleep-deprived
or is having trouble falling back asleep,
that these things like,
and I acknowledge this is essentially like yoga nidra,
but we now call it non-sleep deep rest or NSDR
because oftentimes names like yoga nidra
act as a kind of a barrier
for what would otherwise be people willing
to try a practice.
It sounds mystical, it sounds like flying carpets
and it sounds like you have to go to Esalen,
by the way, Esalen’s a beautiful place,
but it sounds like you have to go there
or live in the West Coast to believe in this stuff,
but it’s simply not the case.
These are practices that are really just
self-directed relaxation as a practice
that allows people to get better and better
at directing their brain states towards more relaxation.
And most people have an asymmetry,
for instance, most people can force themselves
to stay up later,
but they have a hard time going to sleep earlier.
And that just speaks to the asymmetry
that’s probably adaptive and survival-based
that we can ramp ourselves up far more easily
than we can tend to calm ourselves down.
And actually, to appeal to other Christians like me,
prayer can be a wonderful way to calm yourself down
because through prayer, you’re giving your cares to God
and saying, you know, and then you are relaxed,
And I just want to say that
because the same reason that yoga might put some people off,
it might put some people off to talk about prayer,
but it’s the same process of being able to relax.
And get outside our own experience a little bit.
Get outside our own experience, yeah.
Back out, get a worldview
that might actually also help us to relax.
Well, you might be surprised at how many clinicians
and scientists who’ve come on this podcast
have mentioned things like prayer from various perspectives,
Christianity, Judaism, Muslim traditions, and others,
that as a parallel to all of these things.
And I think what it speaks to is the fact that
ultimately the biological architectures
that we’re all contending with
are going to be identical, right?
And so different ways to tap into them
and ones that are congruent with people’s beliefs,
I think are great.
Yeah, because anything non-congruent with your beliefs
is also stressful.
Right, and feels forced.
And that’s why this idea of calling it non-sleep deep rest
in addition to yoga nidra was not to detract
from the naming or the history around yoga nidra,
but I was finding that it was a barrier.
Likewise, yoga nidra tends to include things like intentions
whereas NSDR scripts,
and by the way, we will provide links
to some NSDR and yoga nidra scripts,
but NSDR has no intentions.
It’s simply body scan deep relaxation based.
So it’s sort of the scientific version
of all of this stuff.
And actually we study it in the laboratory
and some of the brain states that people go into,
but that’s a discussion for another time.
Well, another thing, this is hard now.
My mother used to tell me when I would complain,
I can’t go to sleep.
She’d say, well, you know, start with your toes and relax.
So you would clench your muscles around your toes
and you relax them and do that all the way from your toes
all the way to your head.
And I don’t know where she got this.
It might’ve been her own common sense
or she might’ve gotten it from this NPR show.
It’s called the Mind Can Keep You Well.
She used to listen to,
but that’s another intentional relaxation
that focuses on the body
rather than on your own mental processes.
I do a little bit of work with the military
and there’s a method within certain communities
of special operations in the US military
where if they can’t sleep
or they’re having challenges sleeping,
they will deliberately try and relax their facial muscles
in particular, like sort of drape the facial muscles
and use long or exhale-emphasized breathing
does seem to increase the probability
of transitioning back into sleep.
And those are hallmarks of yoga nidra,
non-sleep deep rest, body scans.
And so I think all of these things converge
on a common theme.
You know, as neurobiologists, we can say
all of the things that we’re describing
certainly move the needle away
from locus coeruleus activation.
I mean, we haven’t done the experiment
to really look at that,
but it seems all these things are counter
to noradrenaline release.
Another one is yawning.
Yawning in itself is that kind of sort of tensing
of all the muscles in your face and then relaxing them.
So it might be why we yawn.
We don’t know why we yawn yet,
but it might also be really great.
Actually animals yawn too, you know.
My bulldog was a perpetual.
If he wasn’t sleeping, he was yawning.
And it would be interesting to see
what yawning does to the locus coeruleus.
Does that also calm and switch locus coeruleus activity?
Because it’s interesting that facial nerve,
like trigeminal nerve, you know,
through the vagus connects indirectly to the locus coeruleus
and has a powerful effect on that.
A common, I think, friend of ours
and direct colleague of yours, Jack Feldman,
was a guest on this podcast telling us
about all the amazing structures he and others
have discovered in respiration and breathing.
Sounds like we have a collaboration brewing
that the three of us should definitely carry out.
I’d love for you to share with us a little bit more
about the spindles that have come up a few times.
And I don’t know if it’s relevant to this.
So if it’s not, let’s separate it out.
But I’d love for you to tell us a little bit
about the role of sleep in problem solving and creativity.
And if spindles are involved,
then I’ll consider myself lucky
for batching them in the same question.
And if they’re not involved,
feel free to separate them out.
I think they could be involved.
And the reason why I think they could be involved,
because we now know a lot more about spindles.
First of all, the first thing that we knew,
first of all, we ignored them.
Then we thought they had something to do
with keeping us asleep.
And that was their function,
is when an external stimulus came,
they would keep us asleep because they would arise.
But now we know that the density of our sleep spindles,
the number that we produce per minute,
is well correlated with our intelligence in the first place.
And that no matter what your intelligence is,
and no matter what your sleep spindle density is,
if you learn something during the day
and increase your sleep spindle density,
it’s really almost perfectly correlated
with our ability to consolidate that information
and incorporate it into the schema
that we already have in our brain.
So if you try and learn something new,
even if your sleep spindle density at baseline is great,
if you don’t increase your sleep spindles that night,
you’re not gonna use sleep to really incorporate it.
Interestingly, sleep spindles are poor
in those with schizophrenia.
It’s one of the characteristic signatures of sleep
is that sleep spindles are very few and far between,
which might mean that people with schizophrenia
might not be able to incorporate new information
into already existing schema.
And instead it sort of flaps in the breeze out there
and can be accessed erroneously at times
when you don’t want it to be involved.
So I digress.
So sleep spindles and creativity.
So one of the things we now know
through some great studies by Julie Seep and Anita Luthi
is that sleep spindles are accompanied
by an incredible plasticity out in the distal dendrites,
the listening branches of our neurons
that listen to other cortical areas.
So there are proximal dendrites in our neurons
that listen to the external world
and are conducted through the thalamus.
And then there are distal dendrites
which listen to an internal kind of conversation
that’s happening in our brains.
It’s kind of our internal state, really.
And during sleep spindles,
that’s when those distal dendrites are able to best learn
from other cortical areas and from the hippocampus.
It is during sleep spindles that the hippocampus
and the cortex are best connected
and when that incredible plasticity can happen.
When I talk about schema,
that’s a cortical, cortical thing.
That’s when the image of Santa Claus and presents
It’s not through some external thing.
Once we learn those things together,
it’s our cortex that encodes that
and brings those images back up together.
And that’s during sleep spindles when that’s happening,
when there’s big surges of calcium
into those distal dendrites
and where plasticity happens in just huge amounts.
During that sleep spindle stage of sleep,
which is N2 stage,
there’s also another excitatory event
that comes all the way from the brainstem
and projects everywhere in our cortex,
which is called PGO waves.
P for pons, G for geniculate nucleus of the thalamus,
which is where they’re first discovered
and O for occipital area, which is our visual area,
which is again where they’re first discovered.
But in fact, it’s now been shown that PGO waves,
which we should generalize to P waves
because they come from the pons and go to the thalamus
and then the cortex happens all over the brains.
And that is where glutamate,
which is a major excitatory neurotransmitter
involved in learning and plasticity
is being released in big amounts
also in those distal dendrites.
So P waves and spindles work together to cause plasticity
and so our schema together,
which could be the origins for insight and creativity.
Now, when PGO waves or P waves are first discovered,
it was thought to be random
because this small area that generates P waves
all over the brain projects all over the thalamus
and causes P waves all over.
And you don’t measure P waves all over the brain
at the same time.
In fact, it’s just seems sporadic and random.
So that’s probably,
and P waves also happening even more during REM sleep,
rapid eye movement sleep.
So that’s probably,
that’s why people think that REM dreams are so random
is because these P waves are random
and they could generate dreams
because they’re an internal source of excitation
that kind of replaces the outside world
during our dream state.
And so these P waves, if they are random,
could function or could be the underlying reason
why REM sleep dreams are random.
And it might also be why creativity can happen there
is because we’re randomly activating,
co-activating different things in our brain
that we can then sew together.
But it might not be as random as we think.
So that’s a caveat there.
I just learned a lot from you
because I teach brainstem to medical students
and I talk about the pons.
And the pons is like this dense collection
of all these different nuclei
involved in a bunch of different things.
And it’s close by a bunch of interesting things.
And it’s still kind of a mysterious brain area.
But when I learned about PGO waves,
I thought pons, geniculate, occipital,
because occipital is most commonly associated
with the visual cortex.
I thought it was the origin
of the visual component of dreams.
It probably is.
I’m very happy to learn that they should be called P waves
because they include lots of different areas of the brain.
And it makes really good sense to me
why the kind of pseudo randomness of dreams,
especially these late night or an early morning,
later in sleep, I should say,
and early morning dreams
seem to be cobbled together from kind of
I mean, you walk through a door
and suddenly it’s a completely different context
Yeah, I like this idea a lot,
but it makes intuitive sense.
It makes biological sense.
It also gives me something to talk about
to the medical students next quarter
when I talk about pons.
Ren, you want to talk about where in the pons
it’s right below the locus surrealis.
It’s called the sub surrealis.
It’s also called SLD, sublateral dorsal nucleus, so.
So note to any aspiring neurobiologists,
there’s a vast landscape of yet to be undiscovered
structure and functions in the pons.
You want to work on something
that is sure to reveal something novel,
work on the pons.
Because it’s in every textbook.
It’s a clinically very important structure.
Sadly, gliomas and other cancers of the brain
can sometimes, can often surface in the pons,
but we still know very little about it.
I read a paper this last year,
and I think it was covered in a bit of popular press,
that during rapid eye movement sleep,
people can solve problems or respond to external stimuli.
Like for instance, they would give them math problems.
They’d whisper in their ear while they were in REM sleep,
you know, what’s two plus two?
And people would say, even though they were paralyzed,
apparently they could still move their mouth
because they’d say four or something like that.
Or they’d say, you know, what’s your name?
And people could respond.
And so that in REM sleep, perhaps people,
some elements of cognition are still active.
I’m glad you brought that up.
What do you think?
And I don’t know the authors of that study.
And listen, if ever I say something wrong,
it’s great on this podcast
because someone will tell us in the YouTube comments.
It’s one of the great uses of YouTube comments.
But I’d love to know your thoughts on that study.
I mean, is that just kind of an odd feature?
Or does this have meaning?
Should we actually care about this result?
There’s no just about it.
It’s really actually intriguing and interesting
and might relate to this paper that I talked about
where we said different areas of the brain
can be in different states at the same time.
So lucid dreaming is another thing
we can’t ask animals to do
or can’t ask them if they’ve done it.
But we can certainly ask humans to do it.
And some people can do it really well.
And it would be really interesting to see
in those people who could lucid dream really well,
whether they spend more or less time
in this asymmetrical state
where one area of the brain is in one state
and another area of the brain is in another.
And it might be that those people can respond
to questions during REM sleep best
are those that have the most asymmetry
or dissimilarity or dissociation
between subcortical and cortical structures.
Or it might be that they’re the ones
with the most symmetry.
We don’t know.
I do worry a little bit about lucid dreaming
because people are, it’s a fad.
People are really excited about it.
And to be able to remember one’s dreams is fun
often unless they’re nightmares.
But it’s really interesting.
Or to be able to direct one’s dreams
if they are nightmares is really wonderful power to have
to be able to redirect a nightmare
that has been repeated to something else
and then kick yourself out of that repetitive nightmare
is really nice.
But I worry a little bit about
because we know so little
about what’s actually going on in the brain.
And if this lucid dreaming state is preventing us from,
for example, from the locus realis from calming down
or the serotonergic system from silencing like it should.
And maybe what we’re doing during this state is,
yeah, we’re activating the learning and memory structures
but in a way that’s maladaptive
in terms of the erasure that we need to do.
So maybe one of the reasons
why most people don’t remember most of their dreams
is for good reason.
Your hippocampus is in a state
where it’s not writing new memories.
In fact, it’s writing out the memories it learned
during the day to the cortex
and it’s immune from incoming new information.
So maybe lucid dreaming is bad
because you’re activating the hippocampus
in a way that’s writing new memories
and it might be really maladaptive
for things like PTSD.
On the other hand,
let me just argue myself right out of this.
When I used to have a repeated nightmare when I was a kid,
my mother, who’s so wise, would tell me,
well, listen, just next time you’re in that dream,
say, hey, I’m in a dream and then change something about it.
So she and I rehearsed what the horrible dream that it was.
It was a big monster running after me
and my legs were like mud and I couldn’t run away
and it was just terrifying.
And that was a dream I would have
time and time again.
She said, okay, next time what are you gonna do
when that monster comes after you?
I’m gonna run away.
No, that’s what you do every time
and it’s always the same outcome.
You can’t run.
So let’s do something different.
Like what could you do that’s different?
So I came up with,
I could turn around and punch it in the nose.
Yeah, that’s great.
So the next time I had that dream,
I did recognize this is that same old dream,
which means that there’s part of my brain
that’s conscious enough to know
that I’m in a dreaming state
and then I didn’t have the courage in my dream
because I was still terrified to punch
or touch the monster in any way,
but I did have the courage to turn around
and look it in the eye and say, no, that was enough.
I said, no.
And that was enough to knock me out of that rut
of that dream so that I never had it again.
I never had that same dream again.
And in fact, it gave me peace about dreaming
because I knew that if ever there was a nightmare
that was just too scary,
I could probably do something to change it
and knock myself out of it.
So even though I don’t recommend lucid dreaming
on a normal day-to-day basis,
if it’s enough that can knock you out of a rut,
one thing that happens with people with PTSD
is they have the same repeated horrible nightmare,
which is often a reliving of the day’s trauma
that they had.
So maybe lucid dreaming can be used on occasion
to be a powerful tool
because there’s so much plasticity that happens
during REM sleep to knock you out of that rut
of reliving that event and just change it.
And you could probably practice that during wakefulness,
rehearse the event that happened that was so traumatic,
and then just introduce a new element,
like now I’m safe.
Now, the sound that was associated
with that really traumatic thing,
I should now associate with something else.
And next time I have that dream, I’m gonna change it.
So that sound is now this new thing
that it should be associated with safety.
And that might be enough, maybe, I hope,
to knock you out of that repeated nightmare
and maybe even start you on the path to recovery
because if you can calm down
about those nightmare states of sleep,
then maybe your locus surrealis,
which is involved in stress, can also relax
and you can do the erasure parts that need to be done.
I love it.
I seem to recall a paper,
and I’ll have to find the reference and send it to you.
We will also put it in the show note captions,
that described a protocol
that essentially matches this idea.
And I think what they had people do
is either cue themselves to a particular smell
or tone in wakefulness,
then to try and recall a recurring nightmare.
Then during the night’s sleep,
they had the tone playing in the background,
which would then cue them to the wakeful state.
They’re still asleep, mind you,
but in the pseudo lucid or lucid state.
And then try and change some variable,
as you’re describing.
Some either look the predator in the eyes
or do something different.
And then in the waking state,
take a little bit of time to try and script out
a different narrative altogether.
And it took several nights, as I recall, or more,
but that they were able to escape this recurring nightmare.
It was like a week or something.
Oh, so you’re familiar with this study.
Yeah, it’s a beautiful study.
I loved it.
We will put a reference to that.
I need to revisit that study.
It was pretty recent,
but I need to dive into it again
because I think I didn’t go as deep into it as I should have.
No, no, but the one thing that you,
that you, well, you said many right things,
but one of the things you said
is that they were able to cue the dreamer
when they knew when they were going to REM sleep,
and then they played the sound or had the odor.
Now, when you’re normally asleep alone in your bed,
you’re not going to be able to cue yourself,
but it might be that rehearsal enough
before you go to sleep is enough to help cue you
to that repeated nightmare,
remembering what the nightmare is,
and then figuring out how to cue yourself
to do something different.
For years, I had the same recurring nightmare
over and over and over again,
and it was so salient and so clear,
and I’m not going to share what it is
because it’s not that it’s that disturbing.
It was just, I think it was the emotional load of it
and just how salient certain features were.
One person who was a real-life person
had a particular clothing on,
and that just served as this cue,
and I don’t know if I ever did any direct work
to try and deal with it,
but now it almost seems silly to describe it.
Well, dreams are usually silly to describe.
Yeah, it was pretty silly,
but it was a pretty violent dream.
Yeah, and your emotional system
is so geared up during REM sleep,
which is another thing we could talk about.
I would love to.
So, locus coeruleus is ideally suppressed,
so we can’t really snore epinephrine.
We can’t act out our dreams.
During these very emotionally-laden thoughts
and storylines during sleep,
this almost starts to sound like a little bit of
a built-in while-sleeping trauma therapy,
because most trauma therapies involve
trying to get people into states of,
counter to what most people think,
you actually want to get close to the trauma
in terms of the narrative,
so you want to try and suppress
the emotional activity of it,
or, and I guess that’s the motivation
for ketamine-based therapies for trauma,
or I’ve also heard, and this is still perplexing to me,
that other waking-based trauma therapies
involve taking people the other way,
making it very cathartic,
take them to the peak of the emotional response,
but then allow that to finally cycle down
into a more relaxed response.
So, please, if there’s anything about locus coeruleus
and dreams that can help people basically
extinguish traumas or traumatic features
to real-life events,
we definitely want to know about them.
Yeah, yeah, well, I think one of the things
that people thought might help after a trauma,
like a school shooting or whatever,
car accident, is to talk about it,
but in fact, that ended up being counterproductive,
and I think one of the reasons why it was counterproductive
is because it didn’t take them back down.
It brought them up and continued
to reactivate the emotions of it,
but then didn’t emphasize the safety effect
that it’s over or help them work through
how they might avoid it again in the future
to calm the sympathetic nervous system down again
before they went to sleep,
and none of these studies has sleep ever been considered,
but to me, that’s the key part,
is bringing down your sympathetic nervous system
before you go to sleep
so that your sleep can be adaptive,
your locus relis can shut off
like it normally does or should do,
and then able to erase the novelty of it.
The other thing that I just mentioned a minute ago
was that the emotional system
is highly activated in REM sleep,
and that’s definitely true,
and that might seem counterproductive
in terms of the nightmares
and how to help REM sleep be a therapeutic thing
rather than reinforcing the emotionality of the trauma,
and I think the key to that, again,
is the absence of norepinephrine,
so even though the emotional system is in high gear,
you can actually divorce those highly activated emotions
from the cognitive parts of the memory
that you have just written out in that N2 stage of sleep
when the sleep spindles are going,
so you’ve just now consolidated the information
that you’ll need to survive and to make that adaptive,
and now you need to divorce from that schema
and from that semantic parts of memory the emotional part
because whenever you remember something,
it’s fine if you remember being emotional at the time,
but you don’t wanna bring back,
and so into that memory,
all of the same emotional systems.
You don’t wanna bring back the heart rate changes
and the sweating and all of that.
You wanna be able to remember all the parts of it
and even remember that you were traumatized
and that you did cry
and that you did have, your heart was racing,
but when you’re talking about it years later,
you don’t wanna have to relive all that,
otherwise who would ever want to recall a traumatic memory
because you’re basically putting yourself
through the same trauma,
which is what people with PTSD have.
They don’t want to recall this traumatic memory
because it’s reliving it like it’s just happening again.
So that’s what we’re thinking is that the emotional parts
are not able to be divorced
because the norepinephrine system
is not downscaled during REM sleep,
and so that REM sleep serves to instead reinforce
and in fact amplify the emotions
because your emotional system is up,
locus coeruleus is high,
re-sewing in every night the emotionality of those memories
and with the memory itself.
You’ve told us a lot about locus coeruleus
and norepinephrine from locus coeruleus.
Is there any role for norepinephrine, epinephrine,
and cortisol released from the adrenals?
My understanding is that norepinephrine and epinephrine
will not cross the blood-brain barrier,
which is probably why we have a brain-based
noradrenergic system, locus coeruleus,
and other neurons as well.
Actually, that’s a question I should ask you.
Are there other sites in the brain
where norepinephrine is released from,
or is it just locus coeruleus?
So there are seven, nine different adrenergic,
yes, there’s nine different adrenergic structures.
I should know this.
I’m sorry I didn’t ask, but it just occurred to me
that in some cases, like with Raphae,
there are other sources of serotonergic drive in the brain,
but Raphae is like the main site.
Yeah, that’s the one that goes to the cortex,
and the locus coeruleus is also the one
that goes to the cortex.
But there are other adrenergic sources,
some from the brainstem, that descend and help us
to ignore pain, for example, when we’re stressed
and needing to run away from the tiger, right?
We don’t want to be thinking, oh, my ankle hurts.
You know, you want to just be able to ignore it
and go do what you need to do.
So, yeah, so there are lots of other noradrenergic nuclei,
but the locus coeruleus is the main one
that projects all over the brain.
Actually, the only place it doesn’t project
is the dorsal striatum.
You talked about ventral striatum and addiction.
The dorsal striatum is the only place
the locus coeruleus doesn’t project to,
and that’s involved in procedural learning, motor learning,
the kinds of learning that take over
when your hippocampus, for example, is compromised,
bilateral, if you don’t have a good hippocampus,
you can still do procedural learning, and it’s great.
It’s a redundant system.
And so if your locus coeruleus is not working,
if you don’t have it anymore,
you can still do, if you don’t have a good hippocampus,
you can still do learning
through this dorsal striatum structure.
So it might be for those kinds of learning functions.
Sleep deprivation, where you never let
the locus coeruleus stop firing, is okay
because it doesn’t have any receptors
for norepinephrine anyway, so yeah.
And what about bodily, like adrenals?
I often remind people there’s no such thing
as adrenal burnout per se,
that adrenals don’t actually burn out,
but some people have adrenal insufficiency syndrome.
Other people have adrenals
that are just chronically cranking out epinephrine,
norepinephrine, and cortisol
at the wrong times in particular.
So those are great questions,
and I think the answers to them have yet to be discovered,
the connections between our periphery
and our central nervous system,
but we know that there are beautiful connections,
and it’s untapped source of being able
to manipulate our brains is to work through our bodies.
And so adrenals do great things,
they constrict our blood vessels,
causing higher blood pressure,
which help blood rush out to all the extremities
that need blood in our muscles, for example,
for running away from the lion or the tiger,
or whatever it is.
Or meeting a grant deadline.
Or meeting a grant deadline.
Or catching a train.
Or catching a train, yeah.
The adrenals help our hearts pump faster,
our muscles get perfused with the blood it needs,
it diverts blood and everything away
from our parasympathetic system,
which is rest and digest.
We don’t really need to digest that croissant
when we’re running for a train,
we can do that later.
So it’s doing really important things.
What we don’t know,
because it doesn’t cross the blood-brain barrier,
is how that affects the brain,
and whether our, if we can independently activate
our adrenals when a time when our brain
thinks that we should be fine and calm and asleep,
how our brain detects that.
Is it a feedback through, our heart is racing,
and then our brain stem says,
what’s going on, my heart is racing,
and then wakes us up.
And then our hearts were racing together
with our brain racing.
We just don’t know the answers to these questions yet.
There are some good studies, old studies,
but we need a lot more.
I will, another nod to the fact
that there’s lots of great work ongoing,
and still to do.
I’d love for you to tell us about some of the work
that you’re doing more recently
on the relationship between sleep and opiate use.
Withdrawal, relapse, and craving,
just addiction generally.
I get a lot of questions about people trying
to come off benzodiazepines,
or people’s challenges with benzodiazepine
and other types of addiction.
What is the role of sleep in addiction
and recovery from addiction, and opiates in particular?
Yeah, this is a very young area.
And in fact, my laboratory has just started.
I have a graduate student who’s been
in my lab for just one year.
She’s done amazing work already,
but completely groundbreaking work.
And what she has discovered already,
we don’t have the paper out yet,
but we’re working on it,
is that when animals withdraw from opiates,
and this has been sort of replicated in other ways
with other types of things,
our sleep is disturbed.
Our sleep is terribly disturbed.
And the amount of sleep disturbance
predicts relapse behaviors.
And you might think, well, of course,
you’re going to relapse if you can’t sleep
because opiates calm you down.
Well, one of the reasons why opiates calm you down
is because the locus aureolus, again,
loose fat, is covered with opiate receptors
that are normally really responsive
to our endogenous opiates.
And so what happens when we are pleased, for example,
or laughing or whatever,
our endogenous opiates activate those receptors
in the locus aureolus and calm it down.
And it actually suppresses locus aureolus activity,
makes us happy and relaxed.
One of the reasons why opiates are so addictive
is because it also calms us down and makes us relaxed.
But the problem with exogenous opiates
is that they really strongly bind these receptors
on our locus aureolus.
And if you take exogenous opiates again and again,
like you’re recovering from surgery, for example,
take these pain medications,
is that our locus aureolus struggles
to do what it’s supposed to do,
which is keep us awake and learning
and concentrating on things.
So it will down-regulate,
it will internalize these receptors
that are normally only occupied by endogenous opiates.
And it will do this, it will change our genes
that are associated with producing these receptors.
So you actually have very many fewer receptors.
So the locus aureolus, at least during wakefulness,
can fire and help us to do these things
like learn about our environment.
And so if you long-term reduce
the number of receptors out there,
then when you withdraw the exogenous opiates,
there is not enough of your endogenous opiates
to be able to occupy those few receptors that are there.
And our locus aureolus has nothing to calm it down anymore,
no pacifier, and it just fires and fires and fires.
And that phasic and tonic high activity stresses us out
because it’s normally associated with stress.
And so any exogenous stressor that adds to that
and also activates our locus aureolus,
there’s nothing to calm it down again.
And so it just keeps firing, it disturbs our sleep.
And that’s why maybe sleep disturbance
is an indicator of a hyperactive locus aureolus
and such a good predictor of relapsed behaviors
because nobody likes to live in that high stress state
and they will do anything to get back to normal.
So the problem with taking these drugs
is that it leaves you excited,
or sorry, excited, relaxed and happy.
But then when you come off of it,
you’re worse than when you were at baseline.
You take it again, it only brings you up this far
because you have fewer receptors.
When you come off it,
you’re down even more depressed and anxious.
And depressed is a word I use loosely
and that’s not what I say.
Certainly central nervous system depression.
I mean, sleepier, less motivated, lower mood.
Yeah, I mean, our locus aureolus is actually,
it’s the anxiety kind of depression,
actually the anxiety related depression.
So yeah, so we don’t know yet what,
and there’s some good research going on right now,
what could restore our own endogenous receptors
so that our endogenous opiates
can properly calm our locus aureolus.
Once that they’ve been tamped down by exogenous opiates,
but that would be really one way
that you can access the sleep disturbance.
So we talked about sleep and the importance of sleep
in terms of learning and memory,
the importance of the structure of the 90 minute cycle
for all of that.
So you can imagine if your sleep is disturbed
by too much locus aureolus activity,
the structure and the function of those sleep spindles
and that theta during REM sleep
and the lack of norepinephrine,
all of those structures, all those functions
for learning something new,
like a new behavior that doesn’t involve the drugs
And so that’s something that Tanya Lugo
is in collaboration with Pamela Kennedy at UCLA
that we’re looking at.
How is learning and memory affected
by the sleep disturbance?
If there are way we can,
in animals that have coming off of opiates,
can we restore their sleep to normal
so that then they are less likely
to do relapse kinds of behaviors?
And I will certainly have to have you back on
to tell us the results of those studies.
Meanwhile, I think for anyone who’s trying
to come off exogenous opiates and restore these systems,
what I’m hearing is that it’s going to take some time,
but that any and all things that people can do
to buffer their healthy, normal sleep architecture,
like morning and daytime sunlight,
limiting bright light exposure,
lowering the temperature at night,
a number of things that we’ve talked about
on this podcast.
Calming yourself, deep breathing exercises,
meditation, whatever it is
that helps you calm yourself before sleep, yeah.
Right, would facilitate not just sleep,
but perhaps even accelerate the recovery
and shorten this period of withdrawal,
which from the questions I get and from what I hear
can be absolutely brutal.
Yeah, oh, I can imagine.
I had to take opiates for,
I only took it for three days
after giving birth to my first son, I think,
second son, one of them.
And I just said, after three days, this is enough.
I’m just going to try Tylenol.
And so I weaned myself, not weaned,
I just did a sudden sharp cutoff.
And even though I felt I didn’t get the high of opiates
when I was taking the Tylenol codeine,
when I went off it, boy, it was like PMS times 100.
I was so anxious and upset at little things.
It thankfully only lasted a few hours,
but if I had taken it for a week or two weeks,
who knows if my endogenous opiate receptors
would have been permanently down-regulated
and I would have been an addict, you know,
an addict, I would have been addicted.
I shouldn’t say an addict, there’s negative connotations.
It’s just a very physiological state.
So no judgments at all associated with it.
So yeah, they’re powerful, powerful painkillers,
but can also alter your entire brain and rewire it, yeah.
Well, all the more reason why I and many others
are grateful that you’re doing this work
to figure out ways that people can recover
more quickly and more thoroughly.
I must say, you’ve taught us a tremendous amount
in a relatively short amount of time
about the architecture of sleep, the different phases,
the relationship between sleep and dreaming
and this incredible structure, locus coeruleus.
And I’m so happy we also got into the pons
that just delights me because we rarely talk
about the pons on this podcast,
but it’s such an interesting structure.
Sex differences that are important in creativity
and problem-solving and trauma, sleep spindles,
just such a wealth of information
and much of it that’s actionable for people.
So first of all, I want to say thank you
for taking the time to sit down
and have this conversation
that so many people are sure to benefit from.
I also want to thank you for doing the work you do,
even though I’m a fellow neurobiologist,
I think that it’s not often that we take a step back
and realize that it’s really the work of hard thinking,
hard, strongly motivated PIs,
stands for principal investigator, by the way,
PIs like yourself, graduate students and postdocs
that really drive the discovery forward
and that lead to these new therapeutics.
Physicians are wonderful,
clinicians are absolutely wonderful,
but clinicians don’t develop new treatments.
They only implement the ones that researchers discover.
So thank you for being a brain explorer
with a focus on growing the good in the world.
I know I speak for everybody when I say thank you so much.
Thank you so much, Andrew.
Thank you for being an amazing interviewer.
You brought a lot out of me in a coherent fashion
that normally I can’t do when I’m speaking in public.
I don’t know about that.
I’ve heard your lectures and they’re superb.
We’ll direct people to some of the other ones.
Well, thank you.
And I also want to put a plug in for graduate students
in general and the key and amazing role
that they play in research.
I’m a PI, as you said.
I used to be a graduate student and a postdoc trainee myself
doing all of this on the ground, hands-on experimentation.
It’s so hard to do.
It’s so hard to do right.
It’s so hard to think through all of that.
Now I’m a PI, I get to be an idea person
and just say, hey, why don’t you do this?
And hey, what do you think about that?
And they, of course, intellectually contribute so much
to these planned experiments,
but they also do the really hard work.
And so I just want to say thank you, graduate students.
Thank you to my graduate students
and all graduate students out there.
Thank you, postdocs.
Who are all underpaid and to the major institutions,
Stanford, UCLA, and all other major institutions,
pay them more, please.
We need them and they need to have a standard of living.
I’m not afraid to say that despite my primary employer.
Pay them more.
They need it.
They deserve it.
They deserve it, absolutely.
Great, well, we will absolutely have you back again
if you’ll be willing.
And meanwhile, we will direct people
to where they can learn more about you
and your exciting work.
And once again, thanks so much.
Thank you so much.
Thank you for joining me today for my discussion
about sleep, mental health, physical health,
and performance with Dr. Gina Poe.
I hope you found it to be as informative
and as actionable as I did.
In fact, I’m already implementing the regularity
of bedtime plus or minus half an hour
in order to get that growth hormone release.
And I can already see both my sleep scores improving
and my feelings of daytime vigor and focus
and other markers of sleep health improving as well.
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On the Huberman Lab podcast, we often discuss supplements.
While supplements aren’t necessary for everybody,
many people derive tremendous benefit from them
for things like enhancing the quality and duration of sleep,
for enhancing focus, and for hormone support.
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so checklists of actionable tools that you can use
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Thank you again for joining me for today’s discussion
with Dr. Gina Poh, all about sleep and its relationship
to mental health, physical health, and performance,
and last but certainly not least,
thank you for your interest in science.