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I think it's actually a good sign to not remember your dream. To me, it means that your whole brain was asleep and doing what it should be doing, which is not recording new memories, but rather processing old memories. Don't worry about it. Maybe it's a bummer that you don't remember these crazy dreams that other people come up with and seem so entertaining, but it's actually probably a really good sign that your sleep is efficient and healthy. ♪♪
Welcome to The Knowledge Project, a podcast about mastering the best of what other people have already figured out so you can apply their insights to your life. I'm your host, Shane Parrish. If you're listening to this, you're missing out. If you'd like access to the podcast before public release, special episodes that don't appear anywhere else, hand-edited transcripts, or you just want to support the show you love, you can join at fs.blog.com. Check out the show notes for a link.
Today, my guest is Gina Poe, PhD, a professor in the Department of Integrative Biology and Physiology at UCLA. We discuss sleep, which is her area of research, specifically how it impacts emotions, memory, learning, and more. We also dive into what sleep is, the phases of sleep, dreams, and the effect of routine on sleep and cognitive performance.
This episode is full of practical science-based information you can use to improve your sleep tonight. It's time to listen and learn.
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Let's start by diving in and talking about sleep, which is sort of the focus of this episode. I guess I want to start with what is sleep and what is it for? Which sounds like a very simple question, but I don't know if we're going to get a if it's that simple. Yeah, it's it's for a lot of things. And that's what's great about it. It's not a waste of time. Your brain is really active while you're asleep.
And we know a lot about the functions of sleep right now, whereas even 30 years ago, we basically had very little idea or actually rather lots of ideas, but very little hard evidence that it was for anything in particular.
We know we can't do without it. That's the first thing. Animals that don't get it, for example, there's a biological condition called fatal familial insomnia, and that's where people develop an inability to fall asleep. And unfortunately, it's fatal after a few months.
As you can imagine, they don't develop this. It's a genetic problem and people don't develop this until after childbearing years. And so that's how it is the case that one family and a couple of families in particular have been able to pass this along. But that's helped us to realize that sleep is absolutely essential for life.
And so what do people die of when they don't get enough sleep? Well, it's unclear because it seems to affect multiple organ systems. It affects our brains, our metabolism, our skin, our immune system.
just a lot of things. And so what people die of are various things, depending on what it targets first in them or what it targets worst in them. But in terms of getting sleep, it's for a lot of great things. All those things I just mentioned, it's good for our immune systems and all of our organs, including our brain.
And what it helps in our brain is it helps us to resolve emotions, to learn better, and to actually just clean our brain and restore the energy balance in our brain so that we can function well the next day. How would you define sleep? I want to go into sort of research.
resolving our emotions and cleaning our brain. But before we do that, how would you define? So sleep is behaviorally defined as an inattentive state where we're less attentive to the world around us. It's reversible though, so we can definitely wake ourselves up unlike coma.
And we usually have a characteristic posture and it's homeostatically regulated. So if we don't get enough of it, our brains, our bodies will demand more of it to make up for the sleep that we've lost. We've recently discovered in the last...
five, six years, that sleep isn't necessarily a whole brain at the same time phenomenon. That in fact, some of our brain can be asleep while other parts of our brain can be awake.
And that's probably what sleepwalking is about. We are unconscious, but we are awake enough to be able to interact with the world around us. Is that, do you think, evolutionary in nature? Because we sort of had to be on alert for predators and prey even while we're sleeping and resting. It could be. It's actually just as difficult to awaken a sleepwalker.
than it is someone who's fully asleep. So I don't think it would be evolutionarily demanded. However, there are creatures, not humans, that can sleep one hemisphere at a time, where one hemisphere is awake and has the eye that is governed by that hemisphere is open and actually alert to the world around you.
And the other eye is closed in the hemisphere that governs that eye is asleep. So it's actually just fully awake and fully asleep. Someone asked once whether we could do that. And there is no evidence that we can, but certainly parts of our brain can be asleep while other parts are awake. And that seems to be a not adaptive situation. That's when
We have microsleeps, for example, and we could miss things. When our brain is asleep, parts of our brain that are asleep, including hemispheric sleeping animals, is really asleep. And part of that is being inattentive to the world around us.
We really need to be closed to the world around us in order for sleep to do its thing. And speaking of doing its thing, one of the things that you mentioned was resolving emotions and cleaning out our brain. Can you dive into those a little bit? So both of those have been long suspected to be functions of sleep, but only recently have we evidence that this is the case. We all feel like our brain is full and gunked up when we're sleepy and we need to get to sleep.
But it's only been in the past 10 years or so, we realized that there are actual, the slow waves that we didn't know what their function was when we fall asleep.
are actually sweeping through and cleaning our brains from the debris that builds up across wakefulness. Proteins get misfolded as they get used, and we need to refold them. We also need to clear away the debris of metabolism that happens through these slow waves sweeping through, almost like a bilge pump. I think of it like a bilge pump pumping out the waste.
As far as emotional learning, we all realize that if we don't get enough sleep, we get cranky. And it's even more true of children who are developing. If they don't get their nap or don't get enough sleep, they get really hard to manage.
But it's only been recently in the past 10 years or so that we've been able to see how that happens and mechanistically what is actually happening to our emotions. We still only have a lot of hypotheses and possible mechanisms that should work now. So we still it's hard to study emotional system, especially in animals that can't talk to us.
We can see evidence of volatile emotions, but it's hard to get from mechanistic studies because animals have a difficult time telling us how they're feeling like humans. And it's fairly problematic to deprive people of sleep too much, especially children where it's so obvious. We definitely don't want to deprive them of sleep because it's
Sleep is really important also for a lot of developmental steps that have critical time windows. And if you lose that sleep in that time window, you lose the opportunity to fully develop that part of the brain.
And we're sort of talking about this as if this is a constant process happening throughout the night. But are there different states of sleep or different things happen at different points of time in our sleep? Yeah, there are three kind of gross states of sleep, but people have characterized as many seven sub states of sleep that happen throughout the night.
Typically, we have about a 90-minute cycle. On average, it's about 90 minutes where we go through all the stages of sleep. And they start with first the drowsiness, which is kind of stage one.
where we're being less attentive to the world and we start to have amnesia. If someone's talking to us while we're in this stage one of sleep, we might be able to hold a conversation, but we won't remember it. We could read a page if we're reading a book, but we won't remember what was said on that page. Then we go into a deeper stage, which is stage two. And that is where we start to get sleep spindles, which are these 10 to 15 hertz spindles.
blips in our brains that come and go at different parts of our brains at different times. And these things called K-complexes, which are big surges of activity in our brain,
And that's when we are definitely fully unconscious. But if you wake up someone out of that state or they spontaneously awake out of that state, they will say that they have had hallucinations, kind of like dreams, but not full dreams. They're like they're called hypnagogic hallucinations, hypno being sleep. You know, that's where some of these hallucinations are quite vivid and scary sometimes. So waking up after just falling asleep after about five minutes is
you can have sometimes what our report is as kind of a scary dream that's not a full-fledged dream, but almost like just a perceptual hallucination. Then if we successfully go to the next stage of sleep, that's our deep slow-wave sleep where there's a slowing of our rhythms in our brain and there's periods of silence that last about 100 milliseconds or so, and then periods of high activity, but it's all synchronous.
throughout our brain. And that's synchrony is almost like white noise. You know, it's just everything active at the same time, everything silent at the same time. It interrupts the communication that would happen between the different areas of our brain. So that's a deeply unconscious state of the brain, but it's also a state where if there are portions of your brain that are awake, you could do things like sleepwalking, sleep talking, sleepwalking,
sleep baking, sleep driving. It's pretty dangerous in the sense that you don't really know what you're doing and you're not, there have been cases, legal cases where people have been acquitted out of a crime because it could be shown pretty clearly that they were asleep at the time. After that, we transitioned back to the N2 stage of sleep and that transition on the way to rapid eye movement sleep, which is the dream state, is called the transition to REM sleep.
And that's where really interesting things start happening. We start having more vivid dreams that have a little more content to it. But it's not until we transition to full-fledged REM sleep that we have our full-fledged, long, involved, crazy dreams.
But in that N2 state, again, we have those sleep spindles and those K complexes. And those seem to be really important for helping to consolidate our memories and update our schema with the things that we learned the day before. Yeah, it's just a very plastic time in our brain. And it's really kind of the opposite stage of wakefulness in the sense that
All of the neurotransmitters that are high when we're involved and interacting with our world are low. And neurotransmitters being the neurochemicals in our brain are really low during that N2 transition to REM. And our thalamus, which is our gateway to consciousness, it's where all the outside information gets sorted and put into various parts of our cortexes.
cortex so we can respond normally and rationally to it, it's completely closed. That thalamic gate is closed during that N2 transition to REM. So it's actually in some sense the deepest stage of sleep. We are least awake in that state. And then we go into REM sleep, which is actually paradoxical because often it's called paradoxical sleep because our cortex looks like we're awake.
Our cortex looks like it's responding to the world around us, only it's not because our thalamic gate is still closed. And instead, our cortex is responding to internally generated cues. So instead of excitation coming from the outside world, excitation is driven inside. And it's thought to be random. And that's maybe the source of the randomness of our dreams. But in fact, it may not be random at all. It might be quite directed outside.
to where the functions of that REM sleep dream is trying to accomplish. Oh, man, I have so many questions. We're going to go all over the place here. But one of the things you said is like, if you wake up right away after you go to sleep,
I know that happens to quite a few people, actually. They fall asleep, no problem. And then sometimes they'll wake up sort of like five to eight minutes later, and then they can't go back to sleep. That's really interesting. Well, it might be if you have a really efficient and two-stage sleep, you might be able to accomplish some of the functions of that.
of sleep, including restoring some of the energy packets, ATP, that get depleted across wakefulness. And so I wouldn't worry about not being able to go back to sleep because in fact, I think some of that function of sleep has already been accomplished and that's good. Even some of the memory functions of sleep and creativity functions of sleep could have been
accomplished even in that short period of time. However, the deep cleaning portion of sleep cannot happen within that period of time, nor the refined kind of remodeling of REM sleep could happen. So don't think you can just get away with eight minutes of sleep and be fine for the next day. No. In fact, you do need still to clean your brain.
and to do some refined work and emotional work of REM sleep. So don't worry, but also don't give up. Don't give up on getting up all night.
Should we get out of bed if that's the case? I think it's normal for most people to wake up at least once during the night, whether they're even conscious of it or not, whether they go pee or sort of like some people often wake up at like 2 or 3 a.m. and can't go back to sleep for a little bit. What should people do when that happens? Not beat themselves up, I guess, but like... Definitely don't beat yourself up or get anxious about it because anxiety will inhibit your ability to go back to sleep.
trust your body. And if your body's saying, hey, I really need to get this one thing done before I go back to sleep, I'm not going to feel good unless I get this one thing done. Get up and do it. Just do it and then go back to sleep. You'll feel better. You'll feel better, less anxious, and that will help you go back to sleep. If you're lying there worrying and there's nothing that can be done about it, or at least not done at that time, if it actually requires you to go into the
into work to do this thing that you're worrying about or call someone and it's the middle of the night and you can't talk to them. Instead, try and write a list to help yourself feel more ready to accomplish that thing the next day. Or meditate, deep breathe, try and put yourself back into a place where you are happy and relaxed. And some people, I mean, maybe it just
requires distraction. Maybe playing a mindless video game on your phone with your blue light off. You need to turn down that blue light because that's a circadian clock resetting signal that you don't want. I play threes on my phone. I don't know if you've ever seen threes. It's like you put blocks together to form three and then you put threes together to form six. There's no high stakes in it. It's
It's just enough to occupy my mind so I'm not thinking about other things, but it's not exciting enough to keep you awake. Yeah.
And I just fall asleep beautifully on that. So one of the things you said led me to believe that we sort of dream every night. Everybody dreams every night. Yeah. So why is it some people can remember their dreams and some people like me rarely remember what they're dreaming? Yeah, I think it's actually a good sign to not remember your dream. To me, it means that your whole brain was asleep and doing what it should be doing, which is not recording new memories.
but rather processing old memories. Don't worry about it. Maybe it's a bummer that you don't remember these crazy dreams that other people come up with and seem so entertaining. But it's actually probably a really good sign that your sleep is efficient and healthy. But for those who remember their dreams all the time, also, I'd say don't worry about it because, you know,
What it probably means, and we don't really know the answer to this, again, because we can't ask animals to recount their dreams to us. But what it probably means, and this is something that we just discovered six years ago in animals, and just last year we published it in humans. It's possible that the hippocampus, which is your new memory writing structure, kind of like a thumb drive,
is normally very, it's not very well connected to the rest of your brain during REM sleep, but it might be that it's better connected in people who remember their dreams and it's functioning to record those dreams such that you remember them when you wake up.
So is it good or bad that the hippocampus is better or worse connected with the rest of your brain? We don't know the answer to that. We don't know the answer to that at all. So that remains to be seen. You mentioned sort of kids and sleeping and...
brain development. So I think our brains developed to where, you know, 22 to 25 ish. They're still developing. Yes. So as a parent of two teenagers, what does this mean for me as a parent? Do I wake them up on the weekend? Do I let them sleep until 2pm? How do I what do I do here to encourage brain development? My mom used to wake me up at like seven o'clock with a vacuum cleaner.
I love that. My husband is a physician and people would come to him with that question. And really, it's not a problem with the teenager. The teenager can sleep fine and should sleep. They need that sleep for that brain development.
It's a problem with parents that we don't like it when our teenagers sleep in so late. And it's a problem with school schedules too. Schools are not set up to allow teenagers to both listen to their own biological rhythm, which tells them via combination of signals that children have a very strong circadian clock and it helps them wake up in the morning. It also helps them go to sleep nicely at night.
um teenagers have a circadian clock of course and it's much better than the circadian clock of older people but they have all many other things that their brain and bodies are attending to besides that clock which tends to push their bedtimes to later yet they need just as much sleep as a 12 year old because of all the brain development that's still going on so so that combination of
Later bedtime and needing enough sleep and not having a circadian clock that's quite as strong as a child's allows them to sleep in and get the sleep that they need. They also need more REM sleep. There's a lot of emotional processing, and that happens mostly during that REM sleep stage.
So teenagers who are able to get an extra hour of sleep every night are usually able to better cope with the world around them, including their parents. So they're less emotionally labile. They're happier, less depressed, less anxious, better able to cope with the social pressures of school. I say if it were me, let them sleep.
But my husband, you know, as a physician, you know, helping parents treat their teenagers and also circadian rhythms person himself says, you know, wake them up. So I think either way, as long as they're able to get to sleep at a decent time at night is better. And one of the things that allows a teenager to get to sleep earlier than later is to not have all the electronics and the Facebook and whatever it is that
keeping them engaged, really actively engaged. Make it boring for them at night if possible so that they have less social, emotional reasons to stay up. And part of that is also for the parents to go to sleep at an early time. Parents being awake till midnight, it's hard for a teenager who has so very attuned to the world around them
to be able to go to sleep when stuff is happening in the house. So for parents to make it boring enough that teenagers could fall asleep at a decent hour. It sounds like no electronics, maybe in the bedroom, if you can get away with that as a parent, might be a good sort of... Oh, absolutely. And it's been shown in study after study that teenagers that have electronics far from them, outside the room,
have much better social emotional performance. What have you seen work there? What's effective? Like leave your device in the kitchen or what do you... Leave your device in the kitchen, charging on a... Put the only chargers available in the house outside your bedroom.
And then talk to me about the importance of sort of like routine and timing of sleep. Like how important is the two to three hours leading up to sleep? And then sort of like the consistency around times we go to bed and how that impacts us. There have been studies to show that the more volatile your sleep onset time is,
The worse the cognitive outcomes for older people. So it hasn't really been studied as much in younger people. But if you have a regular bedtime in older people, it's predictive of better cognitive outcomes. Two things control our sleep. Our homeostatic need, which is the longer you're awake, the more you need sleep. And the other is the circadian clock timing of it.
So one thing that helps you to have a good, solid, even circadian clock is in the morning when you wake up, expose yourself to bright light because bright light, especially in the blue frequency, is the strongest resetter of our daily clock. And that starts the clock at the right time of day so that you're ready to go to sleep at night. The circadian clock is one of the things that
its drive for wakefulness starts relaxing at night at the same time that the homeostatic need for sleep builds. And so that allows you to go to sleep at the right time. If you expose yourself to really bright light in the evening, for example, with an electronic device with lots of blue in the frequency of light, you are setting your clock to say, oh, it's time to wake up
And so then your homeostatic need for sleep and your circadian rhythm are fighting one another. Yeah. So there are lots of things that set your circadian clock besides light, timing of meals, timing of exercise, all of that can, can help you know what time it is. So you know what time to go to sleep. It is to go to sleep. Jet lag is a problem because you need to reset that clock and our clocks can,
phase shift by about an hour a day. So if you're flying six hours, time difference, it's going to take you a few days to really reset to that new clock. Now, in terms of what you should do before you go to bed to maximize your
ability to go to sleep. So you have also sort of your autonomic nervous system, which is fight or flight, which is a sympathetic nervous system or rest and digest is an easy way to say your autonomic parasympathetic system. The parasympathetic system dominates as it should during sleep, rest and digest, right?
That does not mean you should eat a big meal before sleep, by the way. But anyway, the parasympathetic system dominates. And so anything that riles up your sympathetic nervous system, the opposite one, is not something you want to be doing right before bedtime.
What does before bedtime mean, though? Is that like the preceding 30 minutes, 90 minutes, two hours? Like, is there a time ascribed to that? I think that varies by individual. For example, I know some people who take a very cold bath.
And then they take a hot shower just to warm up so they're not freezing anymore. And then they get into bed. And what that cold bath does is it actually activates your sympathetic nervous system. You're very aroused. You're very alert and awake during that cold bath. But it almost works like a reset of your sympathetic system. It's like a big reset.
button push that allows a parasympathetic rebound when that stressor is over. So within 30 minutes, you know, once they've warmed up a little bit, they feel so much
more able to get a good night's rest and there's some evidence that the sleep that they get is really you know good sleep for me that doesn't work it's so stressful to me that I just you know it I it takes me too long to relax after that okay but a warm bath is perfect you know because that's helping the parasympathetic system do what it does so um
And it sounds like consistency is sort of key, right? So you're also like every, it sounds, and correct me if I'm wrong here, like everything you're doing during the day is telling yourselves what time of day it is. So you're influencing your sort of circadian,
clock in your head, whether you have coffee or whether you're eating late or playing video games or whatever you're doing, you're sort of like sending it signals. And so it sounds like consistency is sort of the key. And also, if you are consistent, I'm assuming it also talks to your subconscious about, oh, it's a bath. That means we're like queuing our bedtime wind down routine and
Yeah, we are creatures of habit. And it might not just be our conscious mind, but the rest of our body that's also paying attention to that habit and helping us wind down and get sleep. So yeah. And that plays into the time thing too, right? Like sort of like trying to eat around the same window and trying to go to bed around the same window. Yes, exactly. Exactly.
I want to talk about exposing yourself to light, which was you mentioned at the start of that answer, sort of like light exposure first thing in the morning is super important. Should we have blackout blinds in our bedroom ideally? Or is that? Well, during the summertime, if you're in the Northern hemisphere, or I guess no matter where you are during the summertime, the days are light longer.
It's possible that a blackout blind would help you fall asleep better at night. But in the morning, you definitely don't want that blackout blind. You want to open those shades and expose yourself to as much light as possible. Well, first thing, right, when you wake up, is it ideal for people to sleep in a room with a blackout blind, I guess, is the...
And then open it when you first wake up. You know, I suppose if you are in a bright city, you live in a bright city with lots of street lamps that shine directly into your window, then sure, yeah, it'd probably be good to have blackout blinds. Where I live, it's dark enough that, you know, I don't need it. And in fact, I like to have it.
my windows open or the shades open just because that wakes me up in the morning with morning light better. Totally. And what sort of things can we do to make our sleep more efficient and maybe encourage more REM sleep? Because you seem to think that that was part of the most valuable parts of sleep.
You know, actually, one of the things that we don't know yet is whether quantity is equivalent to quality, right? And so more is not necessarily better. In fact, there are some sleep disorders where people have hypersomnia, hypersomnolence,
or too much REM or REM too early in the night. So it's also the timing relationship between the sleep states that seems to be important. If you are learning something or have an emotional day, that you will get more REM sleep. It's homeostatic. It's automatic. You don't need to worry about it.
you'll get it, your body will get it if it needs it. And so if you're learning a lot and you need more REM sleep to consolidate that, it will get more REM sleep at the cost of other states of sleep. If you can just sleep longer than those other states of sleep, don't have to suffer in addition to it. In the first half of the night,
you get more of that deep slow waves, you know, cleaning sleep. And in the second half of the night, toward the wee hours of the morning, you get more REM sleep. So I said on average, you go through all the states of sleep within 90 minutes. But in fact, in the first half of the night, more of that 90 minutes is spent in deep slow wave sleep and less in REM sleep. And in the second half of that night, more of that 90 minutes is spent in REM sleep
and less than deep slow-wave sleep. So if you go to bed too late, you will actually miss the window for that deep slow-wave brain cleaning sleep.
And the sleep you'll get is more REM sleep. If you wake up too early, you go to bed at normal time, but wake up too early, you'll be missing a lot of your REM sleep. So you might be fine in terms of brain cleaning, but you will not have done all the memory consolidation and emotional resolution stuff. That's fascinating. So we don't just catch up if we like go to bed later, we sort of like miss our window, right?
Because it's almost like programmatically our brain starts to do a function at a certain time. And if we're not asleep at that time, we're not getting it, even if we shift our time. Right. But don't fear. Don't worry if you miss a night's sleep or one night you just can't get to bed at the regular time. And the next night you will probably be sleepier earlier. And if you can go to sleep a little bit earlier, that's
you will catch up on that deep slow-wave sleep that you missed the night before. And also, the slow waves become bigger and more efficient. And so...
So your brain will do its best to make up for that last sleep. It'll adjust knowing that you didn't get some last night and so we need to get extra tonight. That's fascinating. There are limits. There are limits to that homeostatic ability to adjust. Unfortunately, we can't just not sleep for a week and then
sleep regularly the next week and just have more efficient sleep and make up for it. That's not the way it works. You will actually suffer. And one of the things that suffers and we don't know how it adjusts is our immune system.
um that's something that gets is able to also learn through sleep for example if you get a vaccine um one day and then um go partying that night and you know drink a lot of alcohol get to sleep late and then that sleep is also influenced by that alcohol so you don't get all the stages and all the quality of sleep that immune immunization
will be at least 50% less effective than it would otherwise be. And you can't make up for that by just getting more sleep the next night. There's a window of time you need to get that sleep for that immune, that vaccination to have its effect. There's a couple of rabbit holes I want to explore there. One of which is what else do we know about the sleep
immunity response connection? There's a couple of great researchers. Mark Opp is one of them. He's at the University of Colorado Boulder. And Jim Kruger, he's at Washington State University. They've done a lot of really good studies to show that our immune system is definitely compromised. The first thing that happens with no sleep one night
is our natural killer cells get upregulated because it's a highly stressful situation for our bodies not to get a night's sleep. And so our immune system goes on high alert and says, what's going on? What do we need to pay attention to? And so that's good. That helps protect us from any kind of acute insults that day.
But it also makes us unable to learn from those things. So we'll learn from whatever immune challenges that you had during that day. And if you're exposed to a virus, for example, you aren't as able to rally your soldiers, your immune soldiers to fight that virus. You will not be able to generate the specific virus.
soldiers to fight that specific virus. And so you'll probably get sick. Why do we sleep more when we're sick or tend to? Yeah. So there is some good studies to show that the immune response actually increases
signals our brain that we need more sleep. So, and it's kind of unknown exactly what's going on and why your body needs more sleep. But if you deprive someone of sleep at the time that they're fighting an infection, they will not get better nearly as quickly. So in fact, it's actually super problematic in a hospital when someone's there for a viral or bacterial illness, something the immune system would need to fight.
and the hospital procedures, the beeping sounds, the checks on you, the blood pressure checks, et cetera, keep you awake or awaken you many times and prevent you from getting that deep slow-wave sleep state. It seems to be slow-wave sleep that's especially important for the immune system. If a hospital environment disallows good quality sleep,
they're actually hurting their patient's chance of getting better as quickly as they otherwise could. Are there studies on that where certain hospitals take sleep more seriously for their patients and therefore we could expect them to have better outcomes and get out quicker? There have been hospitals, thankfully, who have taken sleep more seriously and
only interrupt the patient when it's critical for their life. I don't know of, and it would be good to get back to you on that one, of any studies to see whether or not the patients do better. I would imagine for sure if someone did study it, they would find that to be the case. One thing that has been studied though is whether hospitals take
more seriously, the sleep of their physicians and nurses and staff. And if the schedule of the hospital allows for physicians and nurses and staff to get good regular sleep, then the physicians and nurses make fewer medical errors.
And that includes errors in terms of misprescribing something for the patient, as well as errors that affect their own health, like needle sticks, accidental needle sticks in themselves. Right. Yeah. So the judgment and decision making, the number of accidents go way down if you're
your physician is well slept. So that might be something if you have to go to the emergency room, you just ask the physician, hey, how long has it been since you slept? And how much sleep did you get the last time you slept? And then if it's really a bad situation, you might want to ask for a second opinion before.
That's fascinating. Reminds me of that young Sheldon episode where he starts asking his doctor where he went to school and what kind of grades he got. Yes. Oh, my goodness. Is there do we know of any link between nutrition and the quality of our sleep and what we eat? Because it seems like the function for everything sort of like often comes down to what we eat and sleep.
And I'm wondering if there's a connection between the two of those things. Yeah, I think that is a brand new field that hasn't, we haven't done enough research on it. It was really very recently that we realized that
the enteric nervous system, our whole gut nervous system is as intelligent and influential in terms of our health
as our brain is. So it's not a separate nervous system. They're connected, but they're disconnected enough such that our brain is not really consciously aware of the same things our gut is aware of. So I think it's a really good question. We do know that our microbiome or biome generates neurotransmitters that affect our brain.
And some of those neurotransmitters are really important to either be present or absent during sleep. And so that thing that we mentioned earlier, which is having a big meal just before you go to sleep, having our whole gut work where as normally it should be resting,
might also be generating neurotransmitters that shouldn't be there when we're asleep and could make our sleep less efficient. Well, okay, there's some conflicting evidence. Okay, once it's having a big meal,
Makes people have more nightmares more disturbing dreams that they remember and that probably is because they're awakening out of sleep more often In order to have the consciousness of those disturbing dreams and nightmares but
There have also been studies in babies and in infant rats that a warm, a belly full of warm milk is the best thing for REM sleep. Yeah. So it might be that it might have to do with the complexity of the meal that we've had or how close to bedtime and whether or not we're an infant. But yeah,
Anyway, infants, it's great for a nice belly full of warm milk is great for sleep. It might also be a nice belly full of warm milk is good for adults. There hasn't been a good study on that yet. That's a future area. You mentioned sort of like the diet.
Different parts of sleep at different times, like the first part of sleep is doing X and the latter part of sleep is doing Y was sort of like the deep REM. And the first part is more like the cleansing of your brain. If you had to miss one of those parts and you were forced to choose, do I go to bed late or do I get up early? How would you think about that choice?
Well, I'm a night owl myself, so I would like to go to bed late. But in fact, if I had to choose rationally, it would be getting up early because we do get REM sleep in the first half of the night. And that REM sleep is really important. That REM sleep we get in the first half of the night is really important for learning and memory as well. I would say don't do either. Get your full night's sleep.
Well, I'm just thinking if you had to choose for a flight, say, whether you're getting up early in the morning or you're arriving late at night. So one of which you're going to miss, you're going to miss a certain part of sleep. How would you sort of like go about making that? I get up early in the morning. Okay. I get up early in the morning. Yeah. For one thing, if it's early enough flight, I can actually fall back to sleep and get some dream.
dream sleep on the plane, although the person next to me might find me drooling on their shoulder, but no. You also mentioned sort of like, I want to come back to this, which was the consistency of bedtimes with cognitive outcomes for older adults. Is this something that we can improve if we start making our bedtime consistent and like
adapt back to where we would have been? Have we always had a consistent bedtime or is this something that's sort of like accumulating and we can stop the accumulation of it by going to bed more consistently?
So I think the best way, if you want to start going to bed at a consistent earlier time, you feel like, oh yeah, I do go to bed too late and I don't get enough sleep because of my work schedule or school schedule or whatever it is. So start with wakefulness, start with wakefulness and manipulate what you're doing during, while you're awake. In the morning, even if you're groggy, you know, pull the shades open or go outside, take a walk, um,
Vigorously exercise. Vigorous exercise also helps your sleep do more efficient. Do stuff during the day that helps you be tired at night at an earlier bedtime. So, you know, whether it's getting up an hour earlier or whatever it is so that you can go to bed. Because if you just...
If you don't do that and you wake up nine o'clock and say, oh, I went to bed too late last night. I'm going to get to bed earlier tomorrow. You won't be able to do that because you haven't built up that homeostatic need because you slept in so late, right? So you need to wake yourself up early, suffer through a day of tiredness and go to bed earlier that night. And that will help your clock to reset to that earlier time of wakefulness and an earlier time of sleep.
And then also bedtime routines. That is something that is definitely recommended. Whatever it is that helps your body clue into the fact that it's bedtime. And it's different routines for different people, but, you know, find whatever works for you.
And then hit that beautiful window to glide to sleep when you can. And how long should it take to fall asleep, ideally? Someone who's getting enough sleep at night, you know, takes about, I think, on average, 14, 15 minutes, something like that to fall asleep.
And again, that time shouldn't be stressful. Like, oh my gosh, I should be getting sleep. Oh my gosh, I can't believe I'm still awake. But if it's taking you 45 minutes, that's too long. That means that you're not trying to fall asleep in the right window of time, that you are stressing about something. Or maybe it just means you've had too much caffeine.
During the day too late in the day and that's still working on your brain Keep you rent that signal that homeostatic drive signal from hitting your brain so that one of the
effective ways to help people with that kind of insomnia, that delayed sleep onset insomnia, is to do what we said earlier, get out of bed, do something that relaxes and makes you happy. And then when you're feeling sleepy again, just hit bed. And don't worry about having lost that 45 minutes because in fact, you probably would have been awake the
you know, twiddling your thumbs in bed at that period of time, worrying about it anyway. So get up, do something useful and not too exciting. And that's called cognitive behavioral therapy for insomnia. That's one of the recommendations of it. And it seems super effective. I've had some friends do that and they're like, it takes three or four nights and then it
It seems to work really well. You mentioned sort of falling asleep later. What about if you, instead of 45 minutes or instead of 15 minutes, it takes you like two minutes to fall asleep? What is that? Yeah, that's, you know, good for you. A lot of people feel like it takes me two minutes and it's great. That's wonderful. It's usually a sign that someone's not getting enough sleep. That homeostatic drive is super, super strong. Actually, people are famously bad at knowing how long it takes them to get to sleep.
Because our memory systems, this is a paper we published last year, our memory system is the first thing usually, normally to fall asleep.
So you might not actually be fully asleep. It might be just that your memory system has fallen asleep in two minutes. But in actuality, if you looked at the whole brain, it looks like it's 10 minutes or something like that. However, if you really are asleep in two minutes, like if you have a bed partner and they're snoring in two minutes time after they had to pillow, it's probably a sign that they're not getting enough sleep. Yeah. And also snoring is something to
to be cautious of as well, because it could indicate inefficient sleep of sleep apnea, which is really, really bad for everything that sleep is good for. Oh, that's super interesting. Okay. The question that everybody likes to ask, because I think we just don't like the answer, comes back to...
to sort of alcohol and caffeine and their effect on our sleep and sort of like the windows in which they don't affect sleep as much if there are windows where they don't. I think the half-life of caffeine is like six hours. I don't know what the half-life of alcohol is. Yeah, I don't know what the half-life of alcohol is either, but I wouldn't doubt it's six to eight hours, something like that.
The half-life of caffeine, it's not a half-life of the caffeine molecule itself. It's a half-life of our enzymes ability to break it down and that varies from person to person.
So for me, it's a half-life of more like 16 hours. Whatever enzymes I have, they're just ineffective. I'm maybe more like a dog. A dog doesn't have good enzymes to break down caffeine either. And that's why it's dangerous for them to eat a lot of chocolate or to get into something with caffeine in it. So I think I'm a little more dog-like in that respect. So if I have
If I have caffeine afternoon, I am awake until 1, 2 in the morning. My brain is just whirling, maybe 4 in the morning, depending on how much caffeine I had. But there are other people who have a very efficient caffeine
caffeine enzyme and they can have a cup of coffee at dinner and still sleep great. So I think it really depends on the individual and you need to sort of find whatever is right for you. Alcohol definitely disturbs your sleep. It may make you feel like you can fall asleep better. And a lot of people self-medicate with alcohol before bed. But in fact, even though it helps you fall into that first stage of sleep,
your sleep is not as good or efficient and it actually inhibits REM sleep as long as it's on board. And interestingly, the completion of the metabolism of alcohol, the metabolism of alcohol sends an arousing and alerting message to your brain. So a lot of people, if they're drunk and they fall asleep, they will wake up at three, four in the morning and find it difficult to go back to sleep
Because that alcohol is burned off and that alerting arousing signal has come in. And I don't know what that arousing signal is. I haven't looked into it myself. So...
That's fascinating because there's like a cohort of people I know amongst my friends and other people who sort of like wake up at three to four in the morning and then can't go back to sleep. And I'm wondering to what degree that correlates to having a few glasses of wine or a beer or something the night before and your body is metabolizing it. And then that's part of what's either waking you up or keeping you up if you naturally wake up to pee or something. It could very well be that. Yeah. Yeah.
I want to switch gears a little bit here and talk about some of the stuff you revealed to me before, which is you were raised by, I was struck by this story because you were raised by a single mother, you and your brother, who often wouldn't eat to put food on the table for you. Yeah, yeah, we were, we were really poor on welfare. And, um,
Yeah, my mother would go without meals sometimes in order to feed my little brother and I. My brother's a year younger than me. I didn't know that we were poor. She was very protective of us and didn't tell us, you know, that we were in any way disadvantaged. And she was really resourceful in helping us to find ways to get the essence of what we needed.
But one of the things that we didn't get is visits to the doctor. We didn't have the Medicaid system available at the time when I was growing up. And so routine visits to the doctor didn't happen for my brother and I. And when we got sick, my mother just had to
figure out what to do to treat us herself. And so I didn't get, for example, a vision check until kindergarten when the school did it themselves as part of going to school. And that's when they realized that, you know, I was legally blind in my left eye. And that's something that
they can treat, it was just because of the length of my left orbit is different than the length of my right. And so I just favored one over the other, didn't use my brain, just didn't take the signal from my left eye. And so it's called amblyopia. And so I was essentially just using one eye to get around the world.
And in order to correct that, they had to put a patch over my good eye and force my brain to start listening to and seeing what's coming from my left eye. And that helped a lot. But I still wear very glasses that have much more correction for my left eye than my right. But my 3D vision is probably not perfect yet.
Because of that early developmental deprivation, monocular deprivation. So, yeah, there are definite costs to poverty, whether you recognize it or not. But my mother was just amazing at it.
helping us to get good education, you know, despite the places we were living with poor schools, poor neighborhoods and poor schools. And, you know, she knew that education was the key to getting ahead and being able to not have your options limited in the future. So,
If she saw that we weren't getting a good education, she would pull us out of that school and put us into another one, whether it meant taking a special bus to get there or, you know, other sacrifices to get us to that other school. So we went to a lot of different schools when I was growing up.
One time we tried this experimental school that was supposed to be great for people who were especially smart because they could, you know, in sixth grade, I could take calculus class, you know, if I wanted to. The problem with that school is that it also...
Giving children the choice of where to go also gave me the choice to go play with the animals on the farm, which is what I did. So after about three months of that, my mother went, okay, forget that. You're not going to any classes. We're putting you back into public school. So that's what I did.
And we also used the church that we started going to to get some people donated money so we could get to a private school for some of the years and get some of the benefit of a private education, which is more language learning and other things. So I've benefited both from great public schools and great private schools as I was educated. Ultimately, I ended up going to Stanford for my undergraduate degree.
with lots of financial aid and then to UCLA, which is where I got my PhD.
Your mother sounds like an incredibly strong woman. Very strong, a lot of common sense. And eventually she was able to go back to school for herself once we got old enough and could be left at home while she went to night school. And then when I was in college, she went to college as well. She got a master's degree in public health and she was a hospice nurse.
What would you say is the most important lesson you learned from her that you still think about all the time today? What my mother had best was common sense and just a very rational, even handed approach to the world. She was not.
a radical in any sense of the word. She, you know, went to bed at a regular time every night. She met challenges with, um,
with equanimity and reached out to others when we needed help. And she was a fighter though. She was strong. She never just sat down and let the world happen to her. She got out there and especially for a kid's sake, she fought for us and made sure that we got what we needed. So what she did best for me, I think is just
love me and used, I mean, she wasn't perfect. She had challenges of her own and, uh, but she didn't let those challenges get in the way of raising her kids. Um, and that really taught me strength.
You told me before we started recording that science is way more exciting than it looks on TV. Can you expand on that? Yeah. Oh, yeah. I did not think I wanted to be a scientist because I thought that what I saw on TV was
either the nutty professor where it's someone who's completely socially inept or it was Einstein. It was only for true geniuses. And in fact, and it was for people who didn't mind being loners and just sitting with thinking about and pipetting alone at a bench. You don't see pictures of scientists. You see them alone always, right? Very rarely see them in groups. And in fact, science is an extremely,
social enterprise. We really build off one another's findings and ideas. There's a lot of brainstorming that's a lot of fun. Conferences are amazing. I just came back from a learning and memory conference in Huntington Beach this past week. And just to hear what other people are doing, you know, generates so many more ideas in your own brain about what you could do next.
hearing about the techniques that they utilize, you can start employing them. They will come help you utilize them in your own laboratory. You can go help them. And right now, the pace of science is so mind-blowingly fast that it's almost the case that no matter what experiment you can think of, you can figure out a really good way to approach it with the tools that we have now.
and that we can share with each other and the team science. So you might not be able to utilize this tool, but you know someone else who can utilize that tool to help answer the question and you do this other thing and together those two tools will really help answer the question. When it comes to anything, our hypotheses and our results are sort of only as good as our tools' ability to measure.
And with the brain and sleep, I mean, you know, it kind of feels like we're looking at it from a mile away because nobody wants to let us like drill into their head while they sleep, I would imagine. So it'll be interesting to see how that develops over the next 10 or 15 years. You know, where are we on the right track and where are we totally wrong? And on that note, you know, you have a lot of up and down things
ideas, right? You have a hypothesis, you test it, you discover something completely different. I wonder if you can talk to me about some of that journey. Oh, yeah, absolutely. That's really the fun of science. The science
Neuroscience is like building a giant puzzle that's really difficult, but really rewarding. So every paper that we publish is just one piece of that puzzle. And we don't always know when we come up with the piece where it fits in the bigger picture. And so we actually sometimes
think that it fits with this other thing and I don't know if you ever built a puzzle before but sometimes you think oh this these two go together and they don't quite fit but you think ah you know they've got to fit and you sort of mash it together and it's not until you have more pieces of the puzzle that you realize oh no this other piece goes there and that one actually still doesn't belong anywhere but eventually we're going to find you know the use for it so it's not like
anything that we come up with if we have rigorous approaches to it is wrong. It's just we don't always know where things fit. So sometimes papers get
get published and not cited. And so they are considered low impact papers because for 20 years, no one knows what to do with that knowledge. But the good thing about publications and the record is that they are sitting there and someday someone will say, well, what about that? And they'll find that paper and say, oh, that fits perfectly with this portion of the puzzle that I'm building. And so for me personally,
The way I've come up with some discoveries is because I had a hypothesis that was completely wrong. And in fact, so one of them is that I thought that if REM sleep is for remembering, this memory structure of our hippocampus will be active in one way during REM sleep.
And if REM sleep is for forgetting, like was hypothesized by another researcher, your hippocampus, this memory structure, should be active in an opposite way. And so I wanted to test this hypothesis. I thought it's going to be either one or the other. It's possible that REM sleep isn't for memory at all and it's just going to be all over the place instead.
but it's going to be either one or the other. And the first data set I looked at was for the forgetting, you know, it gave me evidence that it's for forgetting. So I wanted to say, and before I published it, I said, okay, REM sleep is for forgetting because, and then I had to look at another data set for another reason. And I said, okay, let me see how these animals, how the, how REM, how the cells are active during REM sleep in these animals. And I found,
quite different. In fact, it looked like they were all over the place. So I thought, oh, shoot, you know, maybe REM sleep isn't for forgetting because look at this animal's cells are all over the place. But when I had to take those cells and
and parsed them by whether those cells were forming a new memory or just encoding an old, very well familiar, already consolidated memory that the hippocampus wasn't important for anymore. They fired at opposite phases. And the one that was
The phase at which the familiar, already consolidated memory fired was consistent with forgetting. So the hippocampus could be refreshed and able to learn. But the phase at which the cells that are involved in learning something brand new were firing is consistent with REM sleep apnea.
serving a function for remembering and better remembering. So that's the brain telling me that my hypothesis was way too simple. It wasn't one or the other, but in fact, the brain somehow knew whether it was important to forget this thing because now it's remembered somewhere else or
or to remember it because it has not yet been consolidated. And that blew me away. I had no idea. And it took me another, actually, it's been 20 years that I still don't know the mechanism, but I have a brilliant graduate student who's now able with the tools that we've got now, Michelle Frazier, to actually answer that question that we've had for the last 20 years of how it's possible that two cells set up
located right next to each other, but encoding different things can fire at opposite phases. That's incredible. I love that journey and sort of like adapting to the data and being open to it in terms of, you know, I thought this, but now it's this and changing your mind. How do you approach things with that mentality where it's easy to change your mind? Well, first of all, you have to
put your ego to bed because we're all going to be wrong. If we are striving and hot on the trail of something that's real, we have to be open to the fact that we can be wrong and that our hypothesis will always be too simple because our brains are complex. That's one thing that everybody agrees on. And so our hypotheses about how it must work, um, have got to be, uh,
have to embrace that complexity. Putting our egos to bed is the first thing to do. Perfect. And sort of the last question I want to ask you is, what is success to you? How do you think about that? A successful life is a happy life is one where you can,
brighten the corner where you are, whatever you're doing. And I might not have been a scientist had I not happened to have a couple of experiences that showed me that science wasn't as boring as it looked on TV. So I'm really glad that I'm able to do science. But if I had not been a scientist, I'm sure I would have enjoyed my life doing something else, right? I just liked, I think success is to be able to be useful and making the world a better place, no matter what you're doing.
And for me, the thing that excites me, that makes me the happiest, probably the most excited, the thing that makes me jump up and down is when I'm able to put two pieces of the puzzle together that seem to actually fit and come up with some, some answer. I know that I myself, I'm not going to be able to do a huge portion of this huge puzzle, but I'm really glad that I have colleagues that are working on it too, that are also smart and also excited and can tell me about what they're doing so that we can all together, uh,
as a community, solve this really important thing, which is how our brains work and how we can make them work better in cases when they're not working as well. That's beautiful. I love that you said, you know, I believe in this as well, being useful toward making the world a better place. I think that's a beautiful way to end this. Thank you so much, Gina. Thank you, Shane. It's been a pleasure talking with you.
Thanks for listening and learning with us. For a complete list of episodes, show notes, transcripts, and more, go to fs.blog slash podcast, or just Google The Knowledge Project. Until next time.