Hey everyone, it's Stephen Ray Morris. I'm here to tell you a little bit about sleep paralysis and lucid dreaming and where the two meet in the middle, which is me. Sleeping has always been especially lately has been pretty difficult, But for most of my life I've had pretty like stressful dreams, to the point where I feel like sleep isn't very RESTful for me. When I was younger, it used to be really easy for me to fall asleep, but then the actual dreams and things themselves wouldn't be
very RESTful. And that I think like a common theme in my dreams is that I have to do a task in a limited amount of time and there's an obstacle getting in the way. And some of my favorite examples of this are I am like a manager at a brothel Christmas party, and I have to make sure everybody gets their gifts, but all the gifts are unlabeled. I have to catch a train, but I keep running into people I haven't seen in a long time, so hey, nice to see I Actually I got to catch that
train and then I run into somebody else. In college, I started getting sleep paralysis. I still do from time to time, but it was really bad where you know, it's your brain is awake but your body is asleep. So there's usually some sort of demon like nausicle dementor style thing in the corner of the room, and it just causes this intense fear and terror, and so I usually wake up like everyone I've ever is whatever spent the night with, have always had to deal with me
waking up and screaming from these forces. In college, I met my roommate and my buddy Evan who's from the Bay Area, and you know, we all watched Waking Life, and in that movie they talk about lucy dreaming, which is, you know, the ability to be aware that you're dreaming and control your dreaming, etc.
Etc.
The two main things that I took away from it are, you know, like AI, look at your hands or look at clocks, because dreams can't represent either of the things very well, so if you see them, that means you know you're dreaming. So I started continuing these dreams where just this intense fear as this dark figure is looming in the corner, and I, after all this lucid dreaming training or whatever, I started to like wriggle a little bit you know, because I was so scared that I
was really trying to get away. And then one night, as it got right over my bed was looming down at me, I just remember this feeling of a you know, like full like superhero movie like the strain, and I reached my hand out and grabbed this sleep process demon by the wrist, and then I woke up and I didn't have sleep process again for a few years. I still remember this so clearly like it was yesterday, even though this was maybe, like I don't know, almost twenty
years ago. The sleep process still happens every once in a while, but I think my lucid dreaming training still serves me well occasionally, so I'm prepared basically anytime sleep roll Stevens come at me.
Stephen, Stephen, I mean, first of all, terrifying, but also secondly, what a joy to hear your voice.
Thank you so much for sharing your sleep and sleep dreams sleep paralysis story with us.
It is so scary. I've had sleep proalyssis just a few times in my life and I truly thought I was dying.
I know, I don't know that I've ever had it, but all of the stories that I hear, are like really terrifying.
Yeah, yeah, so yeah, thank you, thank you.
Hi.
I'm Aaron Welsh and I'm Erin Allman.
Update and this is this podcast will kill you. Welcome to the exactly Right Studio, Yes, where we will be discussing in two episodes sleep. I'm excited for this very much. So what are we going to be talking about. There's a lot that we're going to cover and we will not cover, so we are going to be typing. This first episode, we're focusing on what sleep is essentially, like, what does it entail, what is your brain doing a little bit about why sleep is important or what we
think sleep is important for. I'm going to be talking about sleep in animals a lot.
I'm really excited about it. I'm excited about too.
I did not know where it was going to go right. And then next episode we're going to talk about some of the consequences of sleep deprivation and also we're going to be talking about the history of human sleep.
I'm really excited about that too. I think the second episode is going to be a lot of interesting discussion about how we think about sleep today.
I think so too. It I personally felt a lot better about sleep.
Oh good, Yeah, that's great at the end of it, happy to hear it, thank you, thank you hopefully everyone, but not this week. No, this week you'll just learn a lot about sleep.
Yeah, I'm excited, and you'll also have a really delicious.
Beverage go along with it, right, because it's quarantin any time.
It is in this case, it's plas breta time because alcohol, spoiler alert, makes you sleep badly.
It's not good for your sleep, even though lots of people use it as a sleep aid, far an anxiolytic.
Hmm, it's not good for either of those.
I mean, alcohol is not good for anything period, not good for your body. There's no safe amount anyway.
Anyways, So.
Is is basically like a really nice version of a Camma meal tea.
But what is it called erin it's called.
Pillar talk.
Yeah, the long pause of be trying to remember.
Well, because we had a few different options. There was also bedtime stortory. Yeah, which would it's a great one. Yeah. Yeah, it's a Cama meal tea plus ginger, honey syrup so good, and a little bit of lemon in there.
Yeah. Kind of wish we had that sound.
Nice sounds good for your throat. Yeah.
Anyways, but you can make one and drink along with us. We'll post the full recipe on our social media channels for sure. Maybe on our website. Aaron walk us through the website.
Oh, the website. Sorry for throwing are Yeah. The website is a real joy to discover. You can find things like transcripts. You can find things like the sources for each and every one of our episodes. You can find links to our bookshop dot org affiliate page, goodreads list, merch, some pretty sweet merch. You can find links to music by Bloodmobile, to contact us, form a first hand account form, and probably some other things. There's an about us page too.
Sure it's not like four lines yep, it does.
Not contain a lot of information.
Oh so check that out.
Check it out, make sure you are rated, rate it, make sure you are rape, make sure you have subscribed and rate it.
Like to review and review the podcast.
We would appreciate that we're doing great. We're really killing it today. Yeah, and if you are a fan of watching things, we're on YouTube on the exactly.
Right so you can see some sweet pjs that we're wearing.
We're pretty excited about it.
I really like, I really like yours. It's very beatle juice.
Yours too, it is very beatle juice.
Thank you.
I love it.
We took a long time picking these out, everyone, so we did. Okay, well with that.
Aaron, shall we take a break.
Business complete it, Business complete. Let's move on to learning about sleep.
Love it?
Okay.
We all sleep, all of us humans, and Aarin, I know that you are going to walk us through some of the many different ways that animals sleep, which I'm quite excited about, Like what does that.
Mean in animals?
What does it mean?
And there's such a variety there.
What does it mean to humans?
Well, let me tell you about it? And that's an interesting question. It's because we all sleep. I think that we all.
Know what it means to sleep.
One could even go so far as to say, much like the Supreme Court Justice Potter Stewart said in nineteen sixty four when trying to define hardcore pornography, I know it when I see it. Yeah, yeah, we all know what sleep is.
But what is sleep?
If we're trying to put like a label on it? What are our brains doing when we sleep? And these are the questions that I'm going to try and answer today, But the biggest question is one that we cannot really answer with what we know, and that is why, exactly why do we sleep? We don't really know truly the function of sleep, but we do have a lot of
thoughts and hypotheses which have various levels of support. So we'll get into some of that as well, and then next week, like we said, we'll talk more about what makes good sleep good and what makes bad sleep bad?
It's so, and then what about like the quantities of sleep and.
Allus we'll get into the architecture of sleep. You get a dollar, okay, So what is sleep? If we define it? Sure, a simplified definition is like a reduced state of voluntary motor activity, so you're not mo you've got a decreased response to stimulation. And in general, there's a stereotypic posture associated with sleep. I know you'll talk more about that aeron, but humans, the thought postures, I know, right, in humans we lay down, right, Yeah, that's what we do for sleep.
And in contrast to other states that might be similar to sleep, like say a coma, sleep is easily reversible, okay, But in reality, in medicine, we have defined sleep based on specific patterns of electrical activity in our brains e g.
Egs.
So let's get into it. We talked about egs or electro encephalograms in our epilepsy episode.
Oh gosh, that was a long time ago.
It was a while back, and at that time I was just like, I don't want to get into it, goodbye, and we just didn't.
Talk to it someday today, today's the day.
So EEG's measure the electrical activity happening in our brains, and the readouts of EEG's when you see them on paper or on a computer, are these wave patterns, kind of like if you've ever edited like a sound file, you see these little wave patterns. They look very similar to that. And waves, if anyone hasn't taken physics in a long time, are measured by two main main measurements, and that is amplitude.
Which is the height of the waves.
And frequency, which is the number of waves per second or per.
Unit of time.
Right, Okay, So the higher the frequency, that means the faster the waves, the closer together the waves are, and we call that a high frequency, and then lower frequency are slower waves. Okay, So longer wavelength, longer frequency. Okay, Depending on what our brain is doing, our EG makes a number of kind of predictable patterns, some of which we only see when we're awake and some of which
we only really see when we're asleep. So when we're awake, our EEG pattern shows these fast frequency, low amplitude waves.
Fast frequency low amplication, high frequency low altitude.
Yeah.
Yeah, so they're like close together waves and they're they're not they're just little little baby waves. And the most common two types of waveforms are called alpha waves and beta waves.
There's a few others too.
Alpha rhythms are like calm, eyes closed, like meditation type of vibes, and then beta waves are what we see more with like activity of the brain.
Sorry, so we're talking about these are sleep, awake, sleep away.
This is what we're doing right now. We're probably beta waving.
We're definitely beta waving, not calm at all.
But during sleep, our EEG patterns change and we can measure more than just the brain electricity. Actually, so when we're measuring sleep, there's three main sets of measurements that we're looking at. The EEG which is your brain electrical activity, the e MG or electro milogram, which records activity in our skeletal muscles.
Okay, and then the EOG.
Or electro oculogram, yes, which is measuring rapid eye movement, yes, horizontal eye movement. And if we put all three of these together, they result in what's called a polysomnogram or PSG. So you can look up a picture of a PSG. But it's like a lot of wires, a lot of Yeah, and sometimes there's more if you're measuring like your pull socks and your heart rate and things like that.
Okay. I've always wondered this about sleep study things. Yeah, I feel like I would sleep terribly.
I know it's a valid concern. I don't have an answer for.
It, Okay, So like how okay, another question, then, how many nights will you sleep with wires, et cetera to get like a good model of what your sleep is?
Like, that's a great question. I don't know a lot of a lot of times.
It might just be one night, just one night, yeah, but it totally depends on what the scenario is, what the study is, and like what information they get from that kind of a thing.
I find that so interesting because I feel like sleep is so variable.
Oh, it's so variable, Aaron, It can totally be so variable. Yeah, So I don't have a great answer to that, Okay, yeah, yeah, totally totally depends on the study and what they're doing, what they're looking for. But based on these PSG readings, what we've done over the years in studying many people for longer periods and in the lab et cetera, we now can divide sleep into two main phases. There's REM
sleep just two okay, well, two main divisions. Y, there's faces within these, but the two main divisions are REM or rapid eye movement sleep and non REM or non rapid.
Eye movement sleep.
Yeah.
Within non REM sleep, there are three different phases sometimes four. Sometimes Stage three and four are separated.
And this is just depending on classification, not like.
Yeah, the older the older literature kind of says there's four stages of non REM and the newer literature is like, realistically, deep sleep is all deep sleep. We'll just call it phase three. Oh interesting, So anyways, it doesn't really matter. But let's walk through what a night of sleep looks like together. Because we fall asleep in relatively predictable patterns and as we fall asleep, our brain waves kind of
get slower and slower as we go. So, like I said before, as we're awake and relaxed, our brain is in this alpha wave pattern, which is low amplitude, relatively high frequency waves. Then as we fall into stage one sleep, which is one of the stages of non rem we call it kind of drowsiness, we'll slip into this pattern called theta waves, which is slightly lower frequency, still low amplitude.
Slightly lower frequency.
So a little longer wavelengths and a little longer frequency than the alpha waves, but still low amplitude.
Okay, little down there.
Muscle eyes, you might have these little like twitches or muscle jerks as we all know why, I don't know. And then stage two is when you start to truly fall asleep. This is when conscious awareness is gone. Your muscle activity decreases substantially, and your brain waves will continue
in this theta wave pattern. But then we see them punctuated by these really weird little bursts of activity, these short little bursts of super high frequency events that are called spindles, followed by what's called a K complex, which is this very it's a low frequency, high amplitude just like one two high amplitude so like wide and tall, weird? Just what and that's a k complex okay, And that's
like stage two. So we see this mostly like slightly chiller pattern, then awake and then little bursts of.
Ye yeah, like a heart almost like a heartbeat kind of yeah.
Sure, we'll say sure, yeah. And then after stage two we fall into deep sleep or slow wave sleep.
Stage three, I'm guessing frequency goes down, yeah, tell me about amplitude.
Amplitude goes up. So we see this high amplitude low low frequency slow waves that we call delta waves.
What is what does it mean to have high amplitude?
You know?
Yeah?
So the waves are created essentially by this like activity of our neurotransmitters happening all at once, and so really it's that the activity patterns in various parts of our brain have slowed down, essentially, is what we're seeing.
For the frequency, right, And what about the amplitude.
I don't know the answer, amplitude, Yeah, I really don't. This is why I'm like not an EEG expert, and maybe someone who is can let us know.
I don't.
But that is deep sleep or slow wave sleep so we'll stay in that sleep for a period of time, don't know how long, depends on you, and then we pop up quickly to stage two. We pass through that pretty quickly, and then we enter our first rem sleep of the night.
So deep sleep is one. That's stage that's the first thing that we encounter.
No, we go we go stage one, Stage two, Stage three, which is deep sleep.
Oh, okay, we'll stay.
There for a little while, and then we'll go stage two. Rem got it, okay. And in contrast to all these other sleep patterns where waves are getting longer and in REM sleep, your brain EEG pattern looks like you're awake. It is an awake beta wave, so not even like a calm alpha wave pattern. It's like a beta wave. This is a type of pattern.
Like we're recording an episode in our sleep. Our sleep.
And REM sleep is also characterized by like a more awake type of physio. Our blood pressure is higher, our heart rate is higher, our respiratory rate is higher compared to non REM sleep.
What about our temperature our body temp.
Oh, that's a good question. I think our body temperature goes up as well too. Okay, still probably not quite as high as it is because in general our body temperature falls with sleep, but it's going to go up compared to deep sleep. Okay, however, we have two weird things happening in REM sleep that we do not see when we're awake, and that is these rapid horizontal eye movements Yep, that happen, and our skeletal muscle activity is essentially atonic.
We really do not move.
We don't so we move even less than we do in our falling asleep twitchy.
Correct, Yeah, you might still have occasional muscle twitches, but in general, your skeletal muscles, so like arms and legs, are not really moving.
I know that this is all foundational, so that someday we will talk about sleep disorders in more details. Yeah, but it is making me want to ask one thousand and one question. Yeah about like what happens when sleepwalking anyway?
We yeah, yeah, sleepwalking is something you'd see more in the deep sleep. In the deep sleep, right, because you're again in REM sleep, your muscles are not moving, right, so in REM sleep we can see things like sleep paralysis. We think that that's like.
You're yeah, because you can't move, you're.
Having basically rem sleep muscle activity, but with an awake brain where you actually do wake up. And that's what we think is happening in sleep paralysis.
And that's all I'm going to talk about when it comes to dreams.
Yeah, FYI.
So in a night of sleep, we cycle through both non REM and REM sleep in a pretty typical pattern. We go from stage one to two to three that quick pickstop at two and then back up to REM and that once we end that REM cycle is considered one sleep cycle. And in adults, a sleep cycle lasts between like ninety and one hundred or so minutes. Okay, so depending on how long you sleep at night, we might go through like four or five or more of these cycles.
Okay, I have a question about give it to me the REM like deep sleep. So I remember reading that deep sleep happens early on in the night. Correct, yes, why, and but REM sleep happens throughout.
We tend to have more deep sleep early in the night, and then like shorter periods of REM sleep earlier in the night and longer periods of REM sleep later in the night, and then it's possible that you might not like later in the night, drop all the way down to that deep sleep like stage three n REM, you might maybe just go to stage two then up to REM a couple of times in your later sleep cycles.
Yes, that is true.
Why I don't know Erin It's also really interesting because like the amount of deep sleep that you get also correlates to how much sleep you got, say, the night before. So if you are sleep deprived and you're running off of like sleep debt as they sometimes call it, then your next night of sleep will likely have more of that slow wave or deep sleep compared to the night before recovery sleep.
Kind of, So the in terms of the breakdown of like I'm the sleep cycle, not even like the number, but just the proportion overall. I'm getting ahead of things you are. Yeah, but I'm what proportion of sleep quote unquote should be REM, should be deep sleep, should be whatever? Stage two?
Yeah, it depends on your age and your stage of life and things like that. So babies have like a lot more REM sleep than adults. They've got like over forty percent REM sleep. Adults it's usually twenty to thirty percent is considered typical, and then twenty I think it's like fifteen to twenty percent. It's in my notes from next episodes, so we'll get more into it. But yeah, it's usually like fifteen to twenty percent or so. Is deep sleep oh or should be deep sleep typical deep?
Oh my gosh, I mean.
And then the rest is that like stage two type of sleep stage yeah, or bouncing between you know, stage one and stage two.
Sort of like that, which is not I mean I feel like deep sleep and RAM are like the stars of the show.
Yeah, they get the crag even though you're not the majority of your.
Sleep, right, which is also important.
It is it is, Yeah, but that is like how your sleep cycle goes throughout the night, and it is going to depend how much time you spend in each one of these from night to night, from person to person, And anybody who has one of those rings or one of those watches that's monitoring your sleep knows that these things are going to.
Very night tonight.
Yeah, So, speaking of which, I just wanted to good.
Yeah, I'm glad you're talking about I just wanted.
To talk about these real quick because there is so much out there right now that's like you need one of these rings to monitor your sleep, and you need to be monitoring your sleep, and these are this one is the best one to be monitoring it, et cetera. I found a paper that was not sponsored by the manufacturer of any of these devices, just the one.
Just one.
There's a lot of.
Papers that are sponsored by that were like funded by the manufacturing of these things, who will say like, oh, these are like seventy five to eighty percent accurate compared to PSGs, Like these are super super accurate. So I found one paper that was comparing a number of different rings.
It wasn't as much looking at the watches that was trying to figure out could these be as good as PSGs that we do in clinic, which is really important because especially to diagnose a lot of sleep disorders, like.
You do need this data, and it's like accessibility and these and all of these things.
Right, So it's like if we could use these clinically, that would be really awesome.
Right, And then you're not having to wear all of these tubes that make you sleep poorly and then you're like you're a terrible sleeper. You need all these things. And it's like I was just.
Had well and like the ability to be able to do it at home is so yeah. So there's so much that would be great if these things were really great, The problem is that they're not.
And it's not that they're not decent.
But I will quote here because I think that this quote kind of summarizes it all. What they said was that even the ones that correlate very strongly with the PSGs, who like on average, agree with what the PSG readings are, they said that quote this agreement masks substantial individual level inaccuracies, prohibiting their use in clinical sleep medicine, as accurate assessment of individual nights, including both nights with exceptionally low or
high quality and quantity, is essential for patient care. So like on average, if you're just looking like population wide, sure they decently, they do decently well, but on a night to night basis, there's a lot of variability in how well it's capturing you as an individual.
That makes sense. So you can't wake up in the morning and go, how was last night?
Right?
Oh yeah, I see what happened? Yes, yeah, yeah, yeah, like we did this morning.
We did like we've been doing the last couple of weeks. So yeah, So that's just what I want to say about those It's like they're not I.
Have heard that, Like, so they're not great at distinguishing between among the stages of sleep, correct, But they are okay at distinguishing awake and sleep.
Yes, so like to get like total duration, they're pretty decent. But again, if you're trying to like understand especially like quality what we call quality and like differentiating between the different stages and things like that, or even if you're trying to and this paper was specifically more looking at people who have, say like obstructive sleep apnea or some other kind of sleep disorder where you really want to be able to get that fine detail, they weren't going
to be effective for that. And most of the studies funded by the manufacturers are looking at like the general population, so like healthy people without any diagnosed sleep disorders or anything. So it's also a different population level.
That we're looking at, right.
So yeah, so that's what we know about those devices. Moving on, before I get too deep into like why what is happening? We know now what our brains are doing as we monitor them, But before we get into the maybe why of it, I want to touch base really quickly on kind of how we sleep, Like what is driving our sleep?
Okay, okay, sleep drive, sleep drive. That's the answer.
We did talk a little bit about this in our circadian rhythm episode, yes, because our circadian rhythm is one of the drivers of our sleep. So as a recap so that you don't have to listen to that episode again. There's a collection of cells deep in like the center front of our brain behind our eyes, deep in our brain that's called the super chismatic nucleus that is the clock of our brain, then the SCN and it basically
generates this close to twenty four hour rhythm. All of our cells do this to one degree or another.
Which is really cool.
It's so cool.
But this is like the master clock that keeps all of our body functions in sync, mostly using signals from light and dark from the sun. Right, and this circadian clock of ours drives things like hormone production, among many other things that help to promote sleep and awake at the right times of day and night for us as
diurnal creatures. But our brain also has other mechanisms aside from just the circadian clock that help to promote both sleep and wakefulness or what's called arousal in the literature, and it's mostly parts of our brain stem.
Right.
And our brain stem is like the deep back part of our brain that connects to our spinal cord.
The stem.
The stem and parts of our brainstem release a whole bunch of neurotransmitters that are involved mostly in promoting wakefulness in wakefulness, right, so promoting us being awake and active during the day. These are things like histamine, dopamine, nor adrenaline, serotonin, all of these types of things that act in other parts of our brain to be like, go do things be awake? Yeah, that's what I imagine they're saying. And we think that sleep ends up happening from a couple things
changing in our brain. One is that there's other parts of our brain closer towards the front of it that send signals to start to inhibit those awake signals. So like, at some point in the day, other parts of our brain will send signals and be like, hey, listen, histamine, chill out a little bit. You've done enough today, So they'll start to inhibit the release of histamine, ou rexin or other signals that are saying be awake.
Be awake, right, and so okay.
And then the other part alway, Yeah, the other part is that and this I think is really interesting we also during the day, like just with our normal metabolism, how our brain is functioning all day long, we are making a bunch of stuff, and some of those things we think act as like sleepy substances, where as they
build up in our brains throughout the day. As the concentration of this substance or these substances really accumulate a our body tissues, including our brain, they increase sleep pressure.
Yeah.
One of the.
Classic ones of these is a dentosine m HM and a denizine we produce just as a byproduct of metabolism, but as we produce that and it builds up in our brain, it makes us more sleepy. Caffeine, Yes, we talked about I was just about to ask about caffeine. Caffeine inhibits the A dentizine receptors, so it tricks our brain into thinking that we don't have a build up of this sleepy substance when we actually do, and that's how it works.
To keep us awake.
What about like mourning though, because if we're starting, are we starting the day fresh? Everything's cleared out? Tell me again about caffeine. It's been way too long since that episode.
So caffeine.
Basically like we because we're making a dentizine, just like from metabolism, we break down atp we make a dentizine. So throughout the day, it's just going to build up, build up, build up, build up, and it's going to bind to these receptors that do inhibition stuff.
That's like go to sleep, go to sleep.
Caffeine binds to those receptors, right, So it doesn't matter how much a dentizy you have, there's nothing for them to bind too, got it, because caffeine is blocking them, and so it tricks our brain into being like there's no identity here, I don't need to go to sleep, and it is quite effective. Like there's so many studies on like caffeine helping to alleviate sleepiness.
I think that like what is so interesting? Okay, speaking for myself, Yeah, I feel like when if I am sleepy during the day or in the evening or whatever, just at any point in the day, I'm like, I didn't get good sleep. I'm really tired, and I feel like I expect that if to get really good sleep or getting really good sleep makes me have no sleep drive, and that's the ideal.
Oh, that's so interesting, you know what I mean? Yea, I shouldn't ever be sleeping.
I shouldn't be sleepy until it's right before bed. And now I just laid back, close my eyes and I'm out boom, and I'm like, that would be great.
I would be great, But like it's not realistic.
It's not realistic. So sleep drive is so important, is what I'm saying.
Well, and it's also it's interesting too because there is this there's like a build up of our sleep drive versus our circadian rhythm, and so sometimes those kind of cross paths at a weird time where we can get more sleepy than we expect in like the middle afternoon
or something like that. And so that's part of why we might feel sleepy at times of day where we think, like, I don't understand why I feel sleepy right now, and it's just maybe because things are you know, it hasn't overlapped in exactly the right way today kind of a thing, But it doesn't necessarily mean that your sleep was terrible the night before, right, So it is really interesting and I'm probably not doing it justice, but there's obviously a lot and it's not just a dentizy.
Right.
There's a lot of other substances that we think are involved in this. So there's a lot that goes into when and how we're sleepy. And some of it, too, is genetics. So we know that some of our sleep drive and a lot of our circadian rhythm, like whether we are a night owl or a morning bird morning morning lark, like, some of that is genetics. There's also some genetic markers that we think are associated with like very short sleep where people sleep very little but are totally fine.
Oh yeah, right, And.
Our need for and our pattern of sleep also changes drastically.
Over our lifetime.
It does.
My favorite example of this are tiny babies.
Oh yeah, because.
Even though fetus is sleep when they are still in utero, they do that like mostly in sync with the human who's housing them. But once a baby is born, they do not have a well defined circadian clock.
It's a mess, it is a disaster, yea.
Their circadian clock is much less than twenty four hours, and their sleep pattern, like I said, a sleep cycle is like ninety minutes. It's much shorter in babies, so they're also cycling through a whole cycle of sleep in much less time, yep, and their sleep pattern is totally random, yeah, completely random, and they'll sleep up till like hours a day like a dog, and not in any pattern that's
compatible with adult sleep patterns. And it's not until the first like six to twelve months of life that they start to consolidate their sleep into these twenty four hour patterns. And because I fell into what is very common these days of being very obsessive about my infant sleep when my first child was born, I have data that you can check out if you're watching the YouTube of my kid's sleep pattern when he was an infant, and you can see that it is literally all over the place.
I don't think anyone listening is surprised that you collected data for how many months.
Of your first kids life? So many months?
Many? I mean the first probably fifteen. That's just one aspect I had. The amount of date I remember too.
There was so much. Yeah, the second one I didn't do any of that. But you can then see that by eleven or twelve months, even though sleep wasn't great, you can see this twenty four hour pattern emerge where there's like a nap in the middle of the day or maybe two naps, But then the majority of sleep is happening over the night time period, and that is because that's how long it really takes for infants to develop this twenty four hour pattern, which I think is
just so interesting. And then the amount of sleep that we need over our lifetime changes too. Kids need a lot more sleep. Teenagers we talked about in our circadian rhythm episode do actually have a shift in their circadian rhythm towards night owl tendencies, and so they tend to sleep later and wake up later, and that can put them out of sync with our modern society. And then as adults, especially older adults, a lot of times we don't need quite as much sleep. So the amount of
sleep that we actually need varies. So why do we need this much sleep? Like why I'm I'm but it's a rhetorical question that I'm going to try and answer, asking the room ask does anybody know?
Does anyone know?
We still like, we still don't really know.
We don't exactly.
What our brains are doing in terms of the function of our sleep, Like.
We know what happens. We know there are bad things that happen when we don't get enough skit correct and that's a lot about that. That's what guides a lot of our assumptions about why sleep is important.
Yes, and like what our brains are really like doing during sleep. Yeah, so we do see and the one of the hypotheses I'll kind of walk through the biggest ones. One of the hypotheses is that it is kind of energy conservation during sleep, and that is because we do see a relative decrease in metabolism during sleep.
However, not really, I mean especially yeah, yeah.
Yeah, especially if you're looking at total body metabolism, Like during rem sleep, our metabolism is essentially the same as when we're awake. Our brain metabolism does decrease substantially, especially during non rem sleep, but again that's only a portion of our total sleep, right, and it's nothing like like our sleep is nothing like hibernation or torpor or something where we're truly decreasing metabolism.
So that's clearly not the whole story. Could be part of it.
There is a lot of evidence that we see changes in things like gene expression, so like certain things turn on and certain things turn off when we're asleep. That only happens when we're asleep, So we think that must be important. But why exactly We don't know. I mean, yeah, because I talked about these like sleepy substances and things like that. We do think that there's sort of like a clean out of the build up of these neurotransmitters that happens during the day.
Detox.
Yeah, brain detox. I hate that word.
It's not accurate, but but we do see like an increase of cerebral spinal fluid flow during sleep and things.
Wash was so I've just heard it described getting rid of all these neurotransmitters and replenishing others. It's very like it's a very satisfying image to think about, just like just like a gentle washing of the brain.
That's what you're hearing as you all asleep anyways, great white noise. How much of is that the function of sleep?
Maybe?
Yeah.
And then one of the biggest hypotheses is that sleep is required for consolidation of our memory.
Memory consolidation. Why do we have to whisper?
I don't know, And we do know there's something called sleep dependent memory processing where there's done. We've done a bunch of studies where if you give humans or animals a task and then deprive them of sleep. They never really learn that task to the same degree that they
would if you let them sleep after it. But even this, the data is a little it's a little bit controversial still that like is this truly the function of sleep, especially because it's like we're trying to compare human brains to like, well, we don't have like lots of animals sleep that don't we don't know anything about their memory.
Oh you'll get to it. You'll get it with those eyebrows.
Sorry, I love it, but but.
Yeah, that's that is one of the kind of big hypotheses that like sleep is essential for our memory.
Okay, but like I don't understand why that's controversial, only in that if it's overstated that this is the function.
That's what it is. That's what it is. It's that it like we know that it's essential.
It is a function.
It is a function. But I think I think.
That it's just that people are so obsessed with this idea that there is like a reason for things.
Nah, that's just sorry, but that's true, right, Like it's not we're not going to get to oh like this like like Laurie will not will not arrive.
It's a bunch of different things happen when we sleep.
I know I'm not satisfying as right, we found it. Here is the answer, the reason for sleep. Right the singular point, that's ridiculous.
We sleep for a bunch of different reasons, and as we'll see you next episode.
If we don't, there's.
A problem a lot of different things beyond memory.
But that's for next episode.
So, Aaron, what I'd like to know from you please is like, obviously, I know my dog sleeps.
My cat all he does is sleep?
Yeah?
Do all animals sleep?
Like?
Oh?
Do they?
I'll tell you, Okay.
In nineteen seventy one, renowned sleep researcher Alan Rechschaffen wrote that quote, if sleep does not serve an absolute vital function, then it is the biggest mistake the evolutionary process has ever made.
I love that, right. Yeah, okay, So.
Let's break that statement down first. Why would sleep be a mistake? Gives us vulnerable to predators and bugs and parasites transmitted by bugs, and it takes up precious time that we could be using to do something else like forage or mate or socialize or read a book, or do your taxes or play with your kids, or exercise, or cook a nice meal, or work more hours at the office. It's so true, so many things. I know that many tech bros view sleep as a mistake.
Oh yeah, you don't even need it.
You don't need it, You could just wake up it three am. Sorry, Wow, I think something just happened there. I liked it, but I mean that aside, though, I do think that most of us have, at one point in our lives wish that we didn't have to sleep as much as we did because we could get so much more done. I know that I have wished that, Like gosh, I could just if I didn't have to sleep as much, I could do things I wanted to do.
It is undeniable that sleep is costly, but it would only be a mistake if we didn't get anything out of it. Okay, Second, does sleep serve a vital function? From what you just told us, erin, it serves multiple vital functions. We may not know precisely how sleep helps us and the pathways that it works along, but we know from experimental and observational research that sleep deprivation is harmful, and that when we lose out on sleep, our body
compensates by increasing sleep. There's like sleep homeostasis kind of totally okay, So now why would sleep be the biggest mistake that the evolutionary process ever made? Because sleep is ubiquitous across the animal kingdom?
Love this.
At this point in our understanding of sleep, it would be much harder to prove that an animal doesn't sleep than determine that it does. Even cavefish species like the Mexican blind cavefish, which has lost eyes and pigmentation and much of their circadian rhythm pattern.
Because they're in the completely.
Darkness, they still retain some sleep. Wow, it's reduced as much as like eighty percent, but still there are indications of sleep. What does indications of sleep means?
Especially in a fit?
I know?
Okay?
So for us to recognize and measure sleep in non human animals, we have to step outside of our human box. So, for one, there's the logistical challenge of recording an EEG on a Mexican blind.
Kfish, Like that's can you do it?
Can you do it? I don't know, it's pretty difficult, challenging. And then for two, we want to be able to observe sleep in more natural settings. And for three it's important to step back from our tendency to make humans like the ideal of the norm, right, like, oh, if you don't sleep like a human, are you sleeping at all? So we can measure sleep elect electrophysiologically using EEGs, and we have done that for a number of animal species,
and we can measure it behaviorally. So researchers use five criteria to say that an animal sleeps. Number one, and it's very similar like you mentioned some of these. Number one prolonged behavioral quiescence basically stop doing stuff, not doing stuff, not doing it. Number two reversible upon stimulation, unlike like you said, torpor or coma. Three a species specific posture, it's not just him, and like laying down or tucking
your antenna away. And then I have a picture of my dog in bagel formation, which is a very he's one of his favorites. Number four increased arousal threshold. So you need a louder or like more substantial stimulus like a noise to get you to respond that if you're awake.
Decreased response to stimulations you maybe like whispering like hey wake up now.
Would you please roll over? Might not do it?
You're snoring, So like your senses are dulled and number five rebound after being sleep deprived, you sleep more. And so these are the things that we can use to say that animal is sleeping because it's doing all these things. And so using these criteria, we can describe and define sleep in a huge array of species like pond snails, octopus, cuttlefish, which may even exhibit rem sleep.
Sorry snails, snails, Oh, it gets even more extreme, yeah, lobsters, mice, armadillos, flies, And funnily enough, whether animals truly sleep is kind of a more recent question.
Ancient scholars like Aristotle fully believed that animals sleep. Of course they sleep. And there's an adorable quote I'm going to read to you from an eighteen sixty five book called Yearbook of Facts. Quote. An insect composes itself to sleep with its antenna folded. Some of the beetles adjust them to their breast. The butterfly seeks some particular aspect of a tree and folds vertically its wings, throws back the antennae, and remains motionless and insensible to all external circumstances.
When caterpillars, which are insatiable feeders, are observed resting, immovable with their heads down. They are asleep.
I love it.
Quote like we don't eat an eeg bro look at the book.
At their little antennae, they're all yeah.
And you can hear them quietly towering. Yeah. So it's so cute.
But it's still helpful to have these specific standards for what counts as sleep because we can then also try to trace the genetic basis and neurological pathways of sleep. Okay, So, for example, Sea Elegance, the research world's favorite worm, contains a mere three hundred and two neurons, wow, compared to an adult fruitfly, which has two hundred and fifty thousand.
So right, and since Sea Elegant sleeps, we can map out the neural pathway of sleep at least in that critter because there are so few.
Wow.
That's really cool, Okay, really cool. But what's even more amazing is that this isn't the quote unquote like simplest creature to sleep. Using those behavioral criteria, researchers concluded that the upside down jellyfish in the genus Cassiopeia sleep.
Jellyfish jellyfish jellyfish.
Unlike sea elegans, these jellyfish. They don't have a central nervous just a nerve net like rings of neurons, And so scientists observed that when the jellyfish is active, their nerve net contracts and causes pulsing behavior that lets them feed and get nutrients. But at night, the pulsing behavior reduces and they become less responsive to external stimuli. And then when you disrupt their resting time, like you keep splashing them with water waves or whatever, they will pulse
even less the next day, indicative of sleep rebound. Oh my gosh, right, I love it, isn't that wild? Yes, And so this means that sleep likely evolved before a central nervous system.
That is so interesting, huge, huge, especially the context of memory and stuff like that.
Right, I mean, okay, yeah, okay, yeah, yeah yeah. But like this is this is an ancient and widespread thing, and so given how ancient and widespread it is, it doesn't really seem like uh.
Sleep is it is a mistake. And as far as I mean, sleep doesn't get fossilized because it's a behavior. But as far as we can tell, no species has entirely lost the capacity for sleep, meaning that it is still so vital too existence. Yeah. Yeah, sleep disturbances or a lack of sleep can have profound effects on health and overall performance, vulnerability to infections, attentiveness, reaction time, memory formation. Mollusks that have been deprived of sleep cannot form new memories.
So like, how do you measure a mollusc's memory?
I don't know. I didn't go that deep.
Now I need to.
I will find the paper, right, And then there are a few gruesome experiments where rats that were completely deprived of sleep for like a long period of time died.
Oh my god, they died.
Yeah. The world record for no sleep, sleep deprivation and a human is eleven days. I heard that two hundred and sixty four hours, held by a San Diego teenager named Randy Gardner who in nineteen sixty five played basketball throughout the night to stay awake. But apparently, like I think in I don't know how they determine this, but they were discovering that he was taking like microground, as of course he was, and so was it truly two hundred and sixty four hours?
You know?
Yeah, I mean his brain was falling asleep. He just did not know it.
He didn't know it, and no one else knew that he was. Yeah, but any that's like, I do not try that at home situation. Yeah, So even though we all sleep in some capacity, we don't all sleep the same. Elephants sleep about half the time that humans do, four hours compared to our eight, which is really more like six to seven. Brown bats sleep about nineteen hours a day, similar to Armadilla's. Koala's sleep even longer, twenty to twenty
two hours. Meanwhile, donkeys sleep about three hours. Cats sleep twelve and a half hours a day, which seems like an underrested.
Absolutely an addressment.
Goats five point three on average, guinea pigs nine point four. I mean, just to show you, it's all over the map. And really many of these sleep duration estimates we do have to take with a grain of s because like we're measuring sleep in the lab, and so there tends to be a bias towards like longer sleep because they're like, I don't have to worry about predators. I've got food here, i've got water, I'm chillen. Might as well take a nap,
might as well just nap all the time. But even still, we do have this huge variation in how much sleep different species need. But duration is just one component of sleep, as we talked about. There's also whether you sleep in one big chunk or multiple times throughout the day or throughout the night, like monophasic sleep is one big chunk, which is what humans usually do big asterisk on that, by phasic sleep, which is two chunks, which is what humans may be used to do, asterisk on that, or
polyphasic sleep like multiple chunks, like a dog who sleeps constantly. Yeah. Whether you tend to sleep during the night time, during or during the day is another big component of this, like a red tailed hawk versus a barn owl for instance, talking birds and not all owls are nocturnal. A lot are crepuscular, So it took me a while to find one that I was like, it's a great word, crepuscular. Yeah, it's very good. There's also whether or not you have remsleep.
So generally speaking, mammals and birds are the only animals with remsleep, except for maybe the cuttlefish. That's so weird, I know, I know, And not all mammals have sleep really yeah, okay, so side note, remsleep evolved after non remsleep as far as we can tell, and it's thought to have emerged in mammals and birds independently.
Oh that's interesting.
Yeah, so, which indicates that it might be really important for cognitive activities or warm bloodedness like aka and a thermy. Oh interesting, Okay, cuttlefish, I don't know.
Cuttlefish are weird ones.
They are so cute. But if you do have remsleep, you know how long are your sleep cycles between rem and non rem. So, for instance, you said human is ninety minutes, or so, the chinchilla is six minutes, six minutes.
They go through a whole six minutes. Yes, Oh my gosh, you're like.
Done and up. There's also whether you sleep with all of your brain or half of it.
That's I think one of my favorite facts I learned in a children's book accidentally before we were It was called sleepy, and that is where I learned about uni hemispheric sleeping.
Hemispheric sleep Yep, it's a real thing, sleeping with one eye open. It was a real thing. Aquatic mammals like whales, dolphins, and seals, as well as some bird species, especially those that are undergoing like long migrations, like.
The what's someone that never touches the land for albatross.
Yeah, is that it?
Oh gosh, I don't know. Sorry, sorry ornithologists, But yeah, union hemispheric sleep. And we've got a little thing here that shows like the eeg of what it looks like when you have like once part of.
The part of your brain is on and part of your brain is off. Yeah, Oh my gosh.
That's so it's interesting, amazing in the right and the left. Yeah. And what's even weirder about this is that whales, dolphins, and porpoises who do this union hemispheric sleep, they don't seem to have rem sleep, or if they do, it's not in a form that we recognize.
Oh that's so interesting.
Yeah. So it's like, did they lose remsleep right when they went back to the oceans? Right, I don't know, I don't know. Okay, but why do aquatic mammals sleep with just one half of their brain? The mean a few different possible reasons, right, So one is because they need to breathe, right, and so they need to be able to come up and have that more active thing. Another is to reduce heat loss. Apparently it's supposed to help with like thermogeneration.
Interesting, And a third is to be.
On the lookout for predators, and a fourth is to stay close to one another because you can really drift apart because if you're just drifting. Yeah, like if you've seen those amazing videos of sperm whales all sleeping vertical and like a like a forest of sperm whales. Yeah, sea otters of course hold hands when they sleep, which is just it's so cute pain sleep cute yep. And unlike terrestrial mammals, newborn dolphins and orca whales are on
the move from the first moment. And unlike human babies, which sleep, like you said so much, so randomly all over the place, these baby dolphins and orca whales are continuously active for like four weeks, like no sleep, you don't sleep at all, no sleep along with mom.
Yeah, fascinating yep, yep.
And it's only after those weeks that sleep gradually returns. And this might be because it's just a really vulnerable time for those babies, it. Yeah. And even when sleeping, these aquatic mammals are moving quite a bit. So dolphins make counterclockwise circles regardless of which half of the brain is.
Sleeping counterclockwise circles.
Why, great question. I do not know. I do not know.
Counterclockwise circles regardless of which part of their brain is sleeping. That is so interesting. I do they sleep? Sorry, I'm gonna ask more details. Do they sleep?
Like?
Obviously it's one half at a time, but is it like consolidated like at night time they're gonna like, okay, forty minutes on this half and then forty minutes on this half or whatever.
Question.
I don't know.
I don't know.
Okay, I'm so I can said.
There's a really great paper that I have I'll shout out at the end that has like a lot more information on this and even like pictures of dolphins sleeping at the bottom of like enclosures and whales and stuff like that. Yeah, yeah, okay. Fur seals listen to this description.
It's very cute.
When first seals sleep in water, they usually float on their sides, holding one front and two hind flippers in the air. The front flipper in the water constantly paddles something cute, and the rest are just like up in the air. One I always open and the other is closed. Wow. Fur Seals also are one of these creatures that spend some time on land and guess what their sleep is like on land like a dog, like any other terrestrial mammal.
But when they're in the water they uni hemispheric.
Uni hemispheric sleep. What And when they're on land, both eyes are closed and they cycle through REM and non rem.
But when they're in the water they don't.
Nope.
Oh that is so interesting, I know, I know.
Oh wow, it makes me like I never I mean, I have like thought about sleep mostly in like a very selfish like am I sleeping enough? Oh my gosh, my sleep kind of away? But this is maybe more interested in rem sleep than like ever.
Yeah yeah, same, Yeah, I did not know any of that.
Yep either. How interesting it's amazing. Yeah, okay, So, but the fact that sleep comes in all shapes and sizes across the animal kingdom and is even variable, like you said, within an individual's life, it shows us that sleep is not random, right, how species sleeps is the outcome of millennia of adaptations. Nor is sleep rigid? Right? There may be times when when we need to go with less sleep, then we you know, ideally like to have migration, mid terms,
having a newborn, I love it, socializing stress. You know, there's a lot of different reasons that might affect our sleep duration, and we can do that, we can sleep with we can have less sleep than we'd like for a limited like a certain amount of time, and then our bodies know to recover from.
That sleep debt.
So if the way that we sleep is not random, what determines how species sleep? Why does a chinchilla have a six minute that? I can't answer that. I don't know about that, but it is. It is a great question overall, and we don't exactly know. And so there are some general patterns that I'll take you through. But
to every pattern there's an exceptions. So if we take all that we know about sleep in animals and we look for similarities after controlling for how related, they are a few strong drivers emerge predation, metabolism, immune function, gestation, length, brain mass, and neuroanatomical regions like the amygdala.
So these are all the parts of things that are contributing to how long and how an animal is sleeping.
Mostly I would say, like how long and the polyphasic versus got it? Yeah, yeah, monophasic, et cetera. Okay, And I don't like there are some aspects of REM and non REM, but like that, I mean, it's just like it's really difficult to draw any sort of yeah, like parallels.
Well, and I feel like it's so interesting because one of the books that I read it was like how you define sleep in animals, Like with this behavioral thing then also affects how we think about and look at.
The why of sleep.
Right, if you define it in slightly different ways, then you might come to a different conclusion as to the function of sleep.
It's a little bit of a guiding hypothesis, that's kind of a thing. Yeah, and you're like, well, if if REM is really the questions that you're asking are driving that how you're looking.
For data, if you're only counting REM sleep as sleep, then your conclusions are going to be totally different.
Or is more REM sleep better?
Right?
Yeah, it's so interesting.
It's really interesting. Okay, so let's talk about some of these some of these different factors. When you're sleeping, you are in a vulnerable state. Your senses are dulled, so you can't hear that twig snap, and you're laying there motionless, looking like a nice tasty snack for that tiger that's you know, just caught your scent and creeping away from there,
creeping towards you. Actually creeping away would be great. So you might be a little better off if you had like a burrow or a tree hole to nestle into. But if you just PLoP down in an exposed area, you're you're playing a very risky, very risky game. Yeah, and so to lower that risk, you might sleep less. And that is what we tend to see. Prey species or species that sleep in more vulnerable locations, like on the ground, as opposed to like in the tree, they
tend to have shorter sleep durations. Interesting and in one experiment, rats that encountered a predator got less sleep afterwards both and they were like edge, you're just on edge. You got to be like you're in lighter sleep. I guess some research actually, some researchers actually suggest that light sleepers and people with insomnia might have those predator or biting
insect vigilance mechanisms on overdrive. So if you're like someone who is really hard time getting into like your wake at the drop of it, like just a little rustle, yeah, you might be. It's just it's adaptive, not anymore of those you won't get eaten. It once was adaptive. Yeah, and so sleeping in larger groups, like larger social groups, that might help counteract them the vulnerability to predators while
you're sleeping. But then there's also the trade off of social disturbances and parasite transmission.
Because you're just like alltogether.
Yeah, but so it's like sleep alone and be easier prey, or sleep in a group and get less sleep, not necessarily worse, but like, and maybe it's more efficient sleep, but it does seem like sometimes it's shorter sleep okay. Interesting, or you could sleep while your predators also sleep okay, and predators tend to get more sleep just on average.
You're like, it's fine, bro right, Like I'm chilling. And metabolism might also play a role in that when it comes to predators versus prey because herbivores, which are more generally more often prey, they need to eat more frequently because they have faster metabolisms or like their food is less calorically dense, and so they have to spend a good chunk of their time foraging, especially if their food is their preferred food is dispersed across the landscape, like, oh,
I have to get fruit trees, and I have to go far to find them, and so you're like you're commute, its long.
Got it?
And you're like, I got to get back to my little burrow.
Yes.
Yeah. Animals with faster metabolisms relative to body size also sleep less and smaller animals tend to sleep throughout the day. They're polyphasic sleepers immune function, so we all know that not getting enough sleep leaves us more vulnerable to infections, and some studies us that species with longer sleep durations have higher white blood cell counts and are less likely to be parasitized.
Interesting.
I think this is a very big generality exactly.
Yeah.
And finally, oh, there's also gestation length. So longer gestations are associated with shorter sleep.
So that's why, like elephants you said get only four hours. Yeah, that's really weird though, why maybe it's just a correlation.
Yeah, it could be they're all metablet I don't. I mean, that's like a lot, and this is like a very much and I don't know episode how interesting though. And then finally, bigger brains like body size. Yeah, and proportion of body size equals a bigger chunk of time spent in REM.
Sleep in REM sleep specifically.
Okay, but again this is all messy. So there was a cool paper though I read that showed how vastly different sleep could be for two closely related species and how similar it could be for distantly related species. So, for since the domestic cat and its relative the genet, a cat gets around twelve and a half.
Hours of sleep, like I said a day with.
Three point two hours REM, and a genet gets about half that six point three hours with one point three hours RIM. And those are like closely related species.
Yeah yeah, and I is that just like because domestic cats are just chillen.
They might be just domestic cats. Yeah. But then there's also a golden mantled ground squirrel and a daegu, again closely related. The squirrels fifteen point nine hours of sleep with three in REM and seven point seven for the daegu with point nine in REM.
How interesting.
So it's not just about like domestication, although I'm assuming that is a decent part of it for the cat.
Yeah.
Then take a guinea pig in a baboon, not closely related, but their sleep architecture is or they're not architecture, their sleep like duration and REM proportion is very similar. They each get about nine point four hours of sleep and one of REM.
That's so interesting.
And in case you were wondering for humans humans, we humans get the same amount of sleep as an Eastern American mole. We get seven to eight hours and we both have about two hours sleep REM. Oh, my gosh. Interesting, that's funny. Yeah, it's really funny. But among primates though humans are the exception, we are at the very extreme end of sleep duration, with some of the shortest sleeps of all primate species. The shortest sleeps.
Yeah, the shortest sleep of all primates.
Yep, huh yeah.
On the other end of the spectrum are owl or night monkeys owl monkeys or night monkeys, which sleep about seventeen hours, but they get the same amount of REM sleep as humans.
That is so interesting. Yeah, oh, I do want to look so much more into REM now. I know, right, what is up with that?
I know what is up with that sleep?
What is up with that?
Based on our human body size, body or brain size, body mass, predation, risks, foraging needs, sexual selection, dynamics, diet, and what we know about other primates like researchers have kind of compiled this model to be like, how should we how should we expect humans to sleep based on what we know about all other primates? And that comes out to nine and a half hours a night.
That's how much we should be getting housted.
Based on these that is not and but we on average it's six to seven hours for humans. And this does not mean that we should all be sleeping nine.
And a half hours.
It's just what the model predicts based on other primates.
So it shows that we are weirdos.
Yes, because evidence, I mean, evidence points to six to seven is normal sleep or six to eight is normal sleep in humans. And it might just be that we somehow squeezed our sleep into a shorter duration, like we're more efficient or intense sleepers. Other grade apes sleep a bit more than humans, but less than like night out or night monkeys and like chimpanzees get about ten hours with similar rem as humans, and gorilla sleep about twelve,
orangutangs sleep about nine, slightly rest less than humans. But when it comes to humans and other great apes, we do share other characteristics. So we have this high proportion of rem sleep and we have nesting behavior, which I just think is adorable. Many of the over four hundred primate species that exist sleep in trees, whether that's in tree holes or on bear branches, just like balancing up there. Even if they spend like much of their waking time
on the ground, they will sleep in the trees. And this might help with like predator avoidance. Probably other species might sleep individually, or they might sleep in groups, or they might sleep on bare ground or on cliffs, like baboons sleep on cliffs and on bare grounds. And some build nests mostly in trees. In fact, all great apes build nests, all of them.
I did not know that.
Yeah, me either. Yeah, And so this suggests that the behavior emerged about fourteen to eighteen million years ago. Interesting, they are built individually, they take between one to seven minutes to construct, and they're usually built every night with occasional reuse.
So they just make their own new nests.
To make their own new nest, yeah, with a bunch of different materials. It's there is so much more about nest building. And I have a paper too, and so why did we start to build nests. It's thought that as body size got bigger in these great ape species, they probably helped to make sleeping more comfortable overall and to protect against damage. If you like fell out of a tree, then like your body.
Was just like a little cushion.
You've got some cushions, so like you're yeah, it makes it more comfortable. And so this also helped to avoid predation. So research suggests that chimpanzees build nests higher and in closer proximity to each other in places when there are where there are more predators. Ah, and also thermal regulation, so you can decide, Okay, is your nest placement going to be higher up or lower down? Do I need more insulation? Do I need to pack in some more leaves,
keep chilli night? Is it nice and warm? You know, like I want to get a breeze up in there. And finally, nests may also help to deter biting insects. So researchers found that some orangutanks built their nests near naturally mosquito repellent tree species when mosquitoes were abundant.
I love this so much, I know.
I mean, if you think about nest building is an incredible behavior and there are some researchers that categorize it under tool use, which would make it the most pervasive among great apes. Wow, yeah, it's environmental problem solving when it comes down to it. Did great apes build nests because they were smart? Or did building nests help make evolve smartness evolve enhanced cognition in Elisha, yeah, chicken or egg? I don't know.
Yeah, I don't know.
But so, like I mentioned, most of these nests are in trees. But humans have long slept on the ground, despite the ground making us more vulnerable to predators, and some researchers have suggested that this ground sleeping, with its more stable surface, would have enabled even deeper sleep, which then allowed us to sleep more intensely fall right, we don't have to have that increased vigilance as much, and so that's what maybe allowed us to shorten our sleep duration.
And then once humans developed the ability to control fire, that would have cut down on the risk of predators and biting insects, and it would have increased our thermoregulation capacities while allowing us longer hours to socialize into the night, exchanging ideas and storytelling, maybe even promoting the evolution of language. And so in short, sleeping on the ground helped to make us become human. Oh right, once we made it
there on the ground. What happened then? Did we just stick to our six to eight hours a night with no breaks? Or is the story slightly more complicated than that. I'm leaving you on a cliffhanger, so you'll have to tune in next week to find out. But I hope you liked this little hodgepodge of a tour through animal kingdom sleep.
I loved it.
It's not a mistake. No, sleep is not a.
Mistake, not an evolutionary mistake.
I think that was mostly said tongue and totally sounded like it.
Yeah.
Oh that was really fun and it made me really excited to find out what humans did with our sleep.
I can't wait to tellt you.
I mean, I don't sleep on the floor.
I don't sleep on the floor. I have slept on floors many times, or on preferred benches. It's horrible.
So I can't wait to hear what we did when sleep.
Well.
In the meantime, there's a lot more reading. You shall we tell the people where to read?
Let us okay, I tell them.
I have many sources, many sources for this one, because I just kept going down rabbit holes.
I loved them all. We didn't even talk about rabbitsleep, didn't.
I actually did have a section where I was I went through each of the animals on my jas to be like, raccoon sleep, this amount, possum sleep, this amount, my favorite animal besides the Tasmanian douvile.
Squirrels, et cetera.
And I cut it because I was like much, it's way too many animals. Okay, you can find more information. There's a book about a lot of animal sleep called Evolution of Sleep, Phylogenetic and Functional Perspectives by McNamara at all from twenty ten. Then there's a great paper I loved from two thousand and eight called Unearthing the Phylogenetic Roots of Sleep by Aladda and Seagull from two thousand
and eight. I think I already said two thousand and eight multiple times by liaman at All from two thousand and eight as well Cetacean Sleep, An Unusual Form of Mammalian Sleep, and finally by Fruth and Stewart, Sleep and Nesting Behavior in Primates a review.
Love it, great stuff. I had.
Most of this information that I shared came from a book from twenty twelve that was called sleep a very short introduction from Oxford University Press. It covers all the But I also enjoyed a paper from Physiological Reviews from also twenty twelve that's weird, that was called control of
Sleep and Wakefulness by Brown at All. And then the paper that was not funded by industry about the wearable finger tracker ring sleep measures was from Scientific Reports published this year twenty twenty five.
Trying so hard not to say any brand name.
I know you know the ones.
I guess twenty twenty five is last year by the time this comes out, doesn't matter anyways. It was by Herberger at all and it was titled performance of Wearable finger ring Trackers for diagnostic sleep measurement in the clinical context. But I have other ones as well to you, and so many more papers, so you can read them all and find them all on our website.
This podcast will kill you dot com.
We will post them all there. Stephen Ray Morris, thank you again, what an absolute delight. It was, really, Thank you so much for sharing your story. Also, sorry that you've had sleep proless. No we're not saying your sleep press.
This was a delight.
No hearing your voice. Hearing your sharing your story, it was wonderful. Thank you and thank you also to Bloodmobile for preventing the music for this episode, in all of our episodes, thank.
You, thank you.
Thank you to everyone here and Exactly Right Studios, as well as everyone who helps make this podcast possible.
Yes, including you listeners. Thank you for listening, patrons. Thank you for patroning your patrons.
Patrons.
Yeah, thank you for everythank you.
Wow.
Until next time, wash your hands animals
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