In this episode: Sleep is biologically necessary for humans, but if we’ve learned anything on SITNS it’s that sleep is also cultural. In this first episode of a double-header, Cressida and Joshua change tack and talk with three sleep scientists about the interaction of biology and culture. In chapter one, Michael Grandner (7:21) explains how life evolved to sleep (meaning, we finally ask: what actually is sleep?!), and Roxanne Prichard (20:51) tells us about the neuroscience of sleep. In chapter two (29:00), we ask our guests how culture influences sleep: from shiftwork to going into space, many human practices present challenges we haven’t evolved to meet. Finally (37:04), psychologist Steve Heine moots the idea that conformity to cultural norms might support sleep health—reversing some of the directions of influence our other conversations implied.
Mentioned in this episode: Michael Grandner’s profile; Roxanne Prichard’s profile; Steve Heine’s profile; Guinness statement on no longer allowing attempts on the world record for longest time without sleep; Peter Menzl’s Hungry Planet photos. Thumbnail: “The Hungry Tree” in Dublin.
Transcript:
Michael: 00:00
There was life billions of years before dinosaurs existed. You know, either the earth cooled, then warmed, and then cooled, and then we've had ice ages, and the dinosaurs came and went in Pangea. Like we have all these things that have changed on Earth throughout the history of life on Earth. But one thing has not changed. That is that the Earth spins on its axis, goes around the Sun.
Joshua: 00:43
Today we're moving in a bold, exciting new direction, and in the first of two episodes, we're going to talk to sleep scientists about how sleep evolved, why h ans need it, and what some of the cultural influences on sleep look like from the STEM disciplines.
Cressida: 01:00
That's right. STEM. Science, technology, engineering, and medicine. So thus far... I feel like I'm bracing myself here...thus far in the podcast, we've talked with scholars from the h anities and social sciences, philosophy, politics, media studies, literature, and so on, all sorts of great people. But of course, there's a whole other world of approaches to sleep, and it makes up by far the lion's share of research. So when I, this morning, opened up Google Scholar.
Joshua: 01:33
As you do every morning.
Cressida: 01:34
As I do every morning and typed in sleep, I got 4.11 million total results. It's scary every time. And you know, they're very diverse results, right? But you do have to scroll for pages to get past the STEM results, even just if you're going chronologically, so you're looking at the most recent publications. And that is itself very diverse. So we're talking about neuroscience, demography, psychology, medicine, all sorts of different things going on here. So there's a lot of excellent research in the h anities on sleep, and part of our mission is to showcase it. That's kind of what we do. But very little research tries to integrate the knowledge we have about sleep as a biological function with sleep as culturally mediated, even though really everybody agrees that it is both those things. So that's what we're trying to do in these two episodes.
Joshua: 02:33
That's right. It's a double header.
Cressida: 02:35
Yeah, I that's a North Americanism that I didn't learn until I was quite old, actually.
Joshua: 02:40
I assume it comes from soccer.
Cressida: 02:41
It's sporting.
Joshua: 02:42
Sporting.
Cressida: 02:43
Something.
Joshua: 02:43
Something else I don't really have any experience in. We're really touching all of my peripheries here, science and sports. in this doubleheader, we decided to interview several different researchers with science backgrounds. And we ended up with a neuroscientist, a psychologist with a clinical practice, a demographer, and a cultural psychologist. And you'll meet each of those people along the way. In our conversations, our main goal was to get our guests thinking about how sleep is both a function of our evolutionary history and our individual bodies, and something that is shaped by the context we live in.
Cressida: 03:23
So sleep, we know, is a biological necessity. Every human being must sleep, that is hardwired into our cells. And we'll hear a bit about how that came about and what it means for our sleep needs. But sleep is also a human practice that's very much shaped by our cultural context. So everybody who researches sleep agrees on both of these claims that sleep is biologically necessary and sleep is shaped by culture. But how do biology and culture interact?
Joshua: 03:55
Yeah, a lot of what we hear in this first episode is going to concern the basics of what sleep is as an evolutionary and neuroscientific phenomenon. And I'm kind of laughing because it's-
Cressida: 04:07
I'm laughing because it feels like we should have done it sooner!
Joshua: 04:10
Yeah, it does feel like a better starting point than even Canadian literature on sleep. And yet it's taken us to season two to finally ask the question what is sleep? What is it? And you know, when you ask that question, it's one of those great, great philosophical questions that seems so, so basic because it's something that we all do, we all try to do. And yet, as we try to define it in this episode, I think you quickly realize just how wide spanning that answer can be. So we started with that question. We started asking questions about how cultural context affects sleep. And most of what we get, especially from the perspective of our colleagues and in the US, concerns how our management of time and organization of work gets in the way of our body's rhythms.
Cressida: 05:03
Yeah, I think it was clear that, including in some of the material that we didn't have time to include, that the the national context or other kinds of context that people work in really shapes how they think about the things that are getting in the way of sleep mostly. Our biological rhythms and our cultural rhythms, often, but not always, not in every time and place, but for us, conflict. And we've certainly talked about that quite a bit in less direct ways in season one. But in addition to accepting our sleep biology as some kind of a given, and then asking how culture overlays it, which is, I think, how we tend to approach these things, right? Like the there's biology, and we need scientists to figure that out, and then there's culture that gets in the way of the biology, and we need people with social science degrees to describe that. But we also tried to find a research project that asked how culture shapes biology. So maybe this was a little contrived, but we wanted to find something where the causal influence went in the opposite direction as well. I think for a lot of people that's much less intuitive.
Joshua: 06:16
Yeah, it goes back to the intuition that we maybe are inclined towards, which is that there is this natural biological phenomenon underneath, and then our cultural attitudes or the social world changes maybe negatively, maybe positively, that biological primary substrate. And I think...
Cressida: 06:39
Or it doesn't really change it.
Joshua: 06:43
Or it doesn't change just gets in the way of it. It affects us. It but what is primary is that biological part, right?
Cressida: 06:50
Yeah, that was there first.
Joshua: 06:51
And yeah, that was there first. And I think that in thinking about the causal directions, it can be helpful to try reversing it to say, well, how is culture really shaping the biological? Yeah. Or it's also helpful to just suspend the which comes first conversation, right? And just enter into how are these interacting, how is the biological shaped by the cultural, how is the cultural shaped by the biological? And that's I think where we are meeting in the middle with our friends in the natural sciences and shaking hands and trying to...
Cressida: 07:25
Détente!
Joshua: 07:26
and détente and trying to map out what that looks like.
Cressida: 07:31
Let's hear a bit about what sleep is.
Cressida: 07:44
Our guest this episode is Dr. Michael Grandner, who is the director of both the Sleep and Health Research Program and the Behavioural Sleep and Circadian Medicine Clinic at the University of Arizona. Trained as a psychologist, he's simultaneously appointed... this sounds like a lot of work, Michael... to the Colleges of medicine, science, and agricultural and life sciences. I didn't really know how to write this introduction because when I looked at your TV and your online presence and your web pages and so on, there's just such a vast array of publications and accolades that I don't really know where to begin. But there's loads and loads of stuff, is what our listeners need to know on the medical and social context of sleep. And it's Michael is one of the very best known figures in sleep science, so today, in the world. So we're very lucky to have him answering our questions as a guest on sleep is the news next. Welcome.
Michael: 08:35
Happy to be here. This is this will be fun.
Cressida: 08:37
So what we're doing is we're trying to do, we're we're taking a little bit of a detour. We're trying to do a couple of episodes where we talk about sleep science with people who have an interest in the cultural and social contexts of sleep, because we do a lot of that second one, the cultural politics of sleep, and when we're not scientists. And yet, as Josh ua and I can attest, everywhere we go, people ask us for sleep tips and tell us about their medical problems, whether we want to hear it or not.
Michael: 09:07
Right. Everyone has a story.
Cressida: 09:09
Everyone has a story. So it's not possible to give any kind of public interview or presentation on sleep without being asked those things. So we thought that we would try and stop people asking political philosophers health questions by introducing some kind of way of framing those questions by talking to sleep scientists. So what we're trying to think of is some parameters for understanding the relationships which go in both directions, I think you would agree, between the cultural context of sleep and individuals, individual behavioural problems or struggles with sleep, or just individual behavior. So we're doing another episode on the theme of the sleep crisis, but we're doing it with a cultural studies and literature scholar who's interested in how the idea is sort of manufactured and represented to us. But of course, that doesn't preclude it being true that there is a sleep crisis. So do you think that there's a sleep crisis? And if so, what is it?
Michael: 10:12
I think crisis is a loaded word. I think that there's a lot of people. Well let me take a step back here to understand why it is that there might be a sleep crisis, and to understand why the social environmental context is so important. I like to start with the question of what actually sleep is, what is it? When most people think of what sleep is, they think of it's something you do at the end of the day. When you close your eyes, you try your best to go unconscious, you usually achieve it to some degree, and then you wake up hopefully feeling better to some degree and ready to go to the next day. Where it's people frame it as a thing they do that achieves a certain outcome. And the degree to which they're able to do it or achieve that outcome is where these stories sort of revolve around. That's not what sleep is. When you when you ask most scientists what sleep is, they're gonna talk about physiologic processes, you know, and circadian rhythms, and they're gonna talk about the hypothalamus and the VLPO and and light, and they'll talk about homeostatic sleep pressure, and like the there's all these things that sleep is doing, like hormone regulation and brain stuff and body stuff and immune stuff, as a sort of a set of things that happen during sleep. That's not what sleep is either. And I think the focus on either of those two things, they're downstream of what sleep is. The focus on those I think distracts people from the real question and what of the why. First of all, sleep is a biological imperative, it's a requirement for human life, just like breathing is. Everyone keeps asking, well, why do we need sleep for anyway? But they don't ask what do we need breathing for? Nobody asks that. And therein lies where the focus should be. What is sleep? Sleep is a foundational aspect of life, of at least for h ans. It is a foundational aspect of our physiology. It's been there since before the beginning. And my own personal belief is that sleep is the emergent experience that happens, the emergent thing that happens when you combine the concept of rest activity rhythms, which exists all over life. You know, evolution figured out a very long time ago that when life is a sprint, it's short. And that rest activity rhythms are critical for survival and development. You combine the concept of rest activity rhythms in life with the concept of circadian rhythms, where when you think about it, there was life billions of years before dinosaurs existed. You know, either the earth cooled, then warmed, and then cooled, and then we've had ice ages, and the dinosaurs came and went in Pangea, sort of like formed the band, and then the band broke up and everyone went their separate ways. And like we have all these things that have changed on Earth throughout the history of life on Earth. But one thing has not changed, and that is that the Earth spins on its axis, goes around the sun in a very predictable way. And and life isn't stupid. Like it doesn't say, like, man, this is an inconvenient thing that happens every day. How can I ignore it? No. What life does is it says, oh, okay, and we call it a light dark cycle. It's not a light dark cycle. We call it a light dark cycle because we're visual animals. It's not a light dark cycle for life, it's an energy cycle. It's a radiation heat energy cycle that pulls away and provides energy and pulls away. And life early on figured this out that if it needs energy to do the things it needs to do to maintain life, it should be doing those things when the energy is present and not doing them when the energy is not present.
Cressida: 14:49
I see. Yeah.
Michael: 14:50
That's why nobody says, well, what do we need breathing for? Like, can we just get around that someday? But people do say, what do we need sleep for? Yes, yes. Because we live in a culture that sees sleep as an unproductive use of time. And there's nothing worse in our culture than an unproductive use of time. There's never time is is is the no one no one says I spend too much time breathing. Nobody says I spend too much time drinking water, you know. but there's social, societal, and environmental pressures that devalue sleep. You know, it's it's as if people are walking around saying breathing unpolluted air is a sign of laziness. You know, it would be like saying if you're eating healthy food, you're living your life incorrectly. Right? That's how we would be talking about it. So the reason why sleep problems exist the way they do is because of our society and our environment and our context, not because of our physiology. Our physiology might have weak points that that the society and the environment exploits or that it hits on that creates pain points. So when I have patients who come in and they're like, I just want to like and I ask, Do you have a dog? And have you ever had a dog? And they'll say yes. Like, do they worry about sleep? No. Does a cat worry about sleep? We're the only and we're the only mammals that worry about it on a regular basis for non-survival reasons. Like, we're the only ones who shift work ourselves on purpose. We're the only ones who sleep deprive ourselves on purpose. That's why the social environmental context is critical. All of these physiologic properties, they're emergent out of what sleep is. That's why they're different from species to species, because there might be different needs. So anyway, that's why understanding the social environmental context is the key, because that's actually the source of the problem. Your sleep, so when a patient comes in, like they say, my sleep is broken, like your sleep's not broken. It's just you're using it wrong. And most of the treatments for insomnia, we can get into this if you want to, actually work by getting out of the way and letting your own natural sleep-wake ability take over and do its thing and get out of its way. That's a more effective way to treat insomnia than any prescription sleeping pill on the market. And I'm not just saying that as an opinion. That is the official opinion of every medical guideline on earth, of every medical organization that has a guideline about insomnia, says the techniques that are all about leveraging your own natural sleep drive and getting out of its way outperform prescription medication.
Joshua: 17:55
So a couple of things that Michael said there stand out. First, sleep is a foundational aspect of our physiology. Then, when life is a sprint, it's short. That one's really catchy. I really like that one. So animals need rest activity rhythms, and these are indexed to the rotation of the earth, and they've been part of our evolutionary history since the beginning of life on this planet. They include periods of cellular regeneration and cognitive consolidation, and we know this as sleep. If we were awake all the time, metabolic waste would build up in our cells, our learning and memory processes would collapse, and we would die in short order, as people with fatal familial insomnia do.
Cressida: 18:36
Yeah, those are those people are really the only example of people who literally never sleep. They don't even micro sleep. And it's very cruel midlife onset genetic disease. And so you don't know that you've got it until you're often 40-something, right? At which point you know that you haven't got very long because once it becomes complete, you're just going to die in short order of a dementia-related kind of symptoms. So terrifying. Yeah, it is really terrifying. So we know from that example that you cannot survive as a human being without any sleep at all. Although, of course, people survive for long periods of time with really terrible sleep. So and we should explain that rest activity rhythm, which is a phrase that participants use, describes the cycles that underlie sleep and waking. So sleep itself is of course cyclical. There's non-REM and REM sleep, and you go through various sleep phases in kind of 90-minute cycles. And our waking life is also organized around periods of cognitive alertness and increasing fatigue. So your degree of capacity to be vigilant or to get dozy changes during the day. And most people have repetitive and somewhat predictable rest activity rhythms that go on during the day as well. And of course, then there's the big 24-hour cycle where you wake up in the morning, theoretically, peppy and rested. And then as the evening advances, you get into that sleep pressure feeling and you desire to lie down and go to sleep for your nocturnal rest. Of course, we've talked so much about people whose sleep patterns don't fit that description, but the idea that there are rest activity rhythms here, even if yours might be eccentric, I think is still valuable. So the story that Michael tells enables us to understand sleep as a very active process that's integral to so much of human systems.
Joshua: 20:44
So our question is why do we sleep? And we also asked that of our neuroscientist guest Roxanne Prichard, and she gave us a slightly different kind of answer.
Roxanne: 21:05
My name is Roxanne Prichard. I am a neuroscientist who trained at the University of Wisconsin back in the 90s, early 2000s, which was a really exciting time for the neuroscience of sleep. I now am a professor at the University of St. Thomas in St. Paul, Minnesota. I'm a mother of adolescent girls. And yeah, just somebody who tries to enjoy life along the way.
Cressida: 21:31
That's great. Thank you. How did you become interested in research on sleep?
Roxanne: 21:36
I think I've, well, I've always loved sleep. I've always been a good sleeper. I've always been somebody who enjoys going to bed, thinking about dreams, and just thinking about where your mind goes during sleep. I remember in college, in a sensation and perception class, asking a question about if you're dreaming of a flying elephant, would it be like the visual cortex actually saw a flying elephant. And the answer was yes. And that was just fascinating to me. So when I started grad school, I met these amazing women, mentors, who were doing a project on how the eyes connect to the brain and how light and sleep interact. And that's how I got kind of, I guess, my formal start in sleep training.
Cressida: 22:25
Yeah, that's I love that. That's a great origin story to say I really like sleeping, because we have quite a lot of people on who say, you know, I have a lot of problems with sleep. And of course, the two aren't mutually exclusive. You can love sleeping and have problems with sleeping. But it's it's good to have fans of sleep, I feel. Yeah. Yeah. It needs more boosters. And this is sort of relevant because your training is in neuroscience. And so for our listeners who don't have any specialized knowledge in neuroscience, which is, I imagine, almost all of them, how would you answer the question? Why do we sleep?
Roxanne: 23:07
We need sleep to live. Like literally, we die without sleep. It's like food, water, air, a requirement for life. It is a process of the brain for the brain, right? So you can rest your muscles by being in a hammock, but we need to somehow...I think it's hilarious. When I think about why do I need to spend a third of my life not interacting with the world in two hours of that or so, I have to be both paralyzed and hallucinating. And I need to do this every night to live. I just chuckle. Like, why does my brain need to get rid of my mind every day so that I can function? But it really does need a break from myself. So the brain in sleep goes into some very distinct processes that are incompatible with consciousness, that are necessary for life, that give the thing the brain needs to do to clean itself. Like everything that eats excretes, and the brain takes 20% of our calories. That's a lot of when I'm talking to kids, I say "brain cell poop" that we need to get rid of when we're sleeping. So the metabolic waste removal is an important process, but also sleep allows the brain to sort through all the experiences we've had in a day and sort of tag what is important, how does this idea or memory connect to another thing I should think about or make note of? And what should I forget? And that's probably more important than what do I need to remember is what do I need to forget. So that process of sort of sorting through and coding, tagging memories and filing them in a way that you can access them again and link them to other ideas is something that sleep allows us to do. And that's a process, again, that we can't do with consciousness.
Cressida: 25:04
Can you say, in a way that someone without knowing anything about neuroscience could understand why that process is incompatible with consciousness? And that's hard.
Roxanne: 25:14
Yeah, that's a that's a hard thing to do. I think part of the reason is just what speed the brain is on. In order for me to be paying attention to the world, in order for me to have my busy internal monologue going, I need my brain at like 12 to 16 kilohertz. Like it's pretty fast. And for me to do the waste removal process of the brain, that needs to slow down to like one kilo, like 16 times slower. So just like the physical way the brain cells communicate and even the physical size of the neurons change. Like the brain cells shrink and our cerebral spinal fluid increases 60%. So much like like a rent cycle on a dishwasher, that our the plumbing and the electricity of the brain are changing in a way that cannot support full perception and full consciousness.
Cressida: 26:17
That's a great answer. I mean, you several of the ways that you said it in your previous answer were also very philosophical, right? Like I need a break from myself, or I yeah, that I forgetting is more important than remembering, which is connected, right? So the idea that there's something about the conscious self that has to be left behind in sleep for the physical reasons that you just described, but also kind of existentially, I would say, you know, I would use that little philosophical word, because I think it's not just a biological imperative that, oh, we've inherited it because evolution, but it's also somehow an important part of our experience as h ans that checking out is vital to the kinds of creatures that we are and maybe even aspire to be. And so one of the reasons I find sleep hacking or even just sleep negativity in general a bit worrying is because of its emphasis on being continually conscious and its prizing of consciousness and the exertion of the self, as if that's all that it is to be human, as if the rest of it is a waste of time. So, do you ever do you ever have thoughts like that in your scientific in your scientific brain?
Roxanne: 27:35
All the
Roxanne: 27:35
time.
Joshua: 27:47
So Roxanne gives us an answer more focused on the plumbing and electricity of the brain than on the big picture of evolution.
Cressida: 27:55
Yeah, these are I think different viewpoints on the same phenomenon. So sleep is necessary for brain function because we evolved that way.
Joshua: 28:05
So if we have a rough picture of the evolutionary origins of sleep and its function for the body systems, what are the implications of that picture for how sleep is culturally shaped?
Cressida: 28:16
Yeah, that's really our main question here. And for both Michael and Roxanne, our sleep needs are being undercut by some of our cultural practices and rhythms.
Joshua: 28:26
Yeah, Michael mentions several things, including our equatorial human origins, jet leg, that we create a jet leg, shift work, and what happens to our sleep when we leave the earth.
Cressida: 28:38
And so maybe now is a good moment to preview the fact that later in the season we have an upcoming episode on sleeeeeep in spaaaaaace.
Joshua: 28:48
You've been waiting so long to do that on a microphone.
Cressida: 28:52
I will never get tired of doing that.
Joshua: 28:54
Yeah, you're looking very forward to that one. And then Roxanne chimes in on the limits of sleep. How long can we force ourselves to stay awake?
Michael: 29:13
What happens when you take humans out of this context? You know, this was this was a problem evolution never had to solve. Just like jet lag, jet lag exists because humans can't run fast enough to worry about time zones.
Cressida: 29:27
Yes, we created it. Yeah. Right. Yeah.
Michael: 29:30
And so like this is our body being like, what are you doing? This makes no sense. Why is it three when my body says it's midnight?
Cressida: 29:37
Yes.
Michael: 29:37
Like this doesn't make any sense.
Cressida: 29:39
I'm jet lagged right now, so I I totally empathize. Right.
Michael: 29:42
And and evolution had no solution for it because again, humans can't run that fast.
Cressida: 29:47
Yes, it was never a problem. Yeah.
Michael: 29:49
And the same thing about living in a non-24-hour day. I mean, to some degree, we we've already learned some of this, where humans come from equatorial environments with very bright days, very dark nights, and relatively little seasonal variation. Remember, humans have been around for about 200 something thousand years at least. And like the human diaspora is what less than 20,000 years old. So more than 90% of human existence was confined to a very specific climate and region and environment and context.
Cressida: 30:29
Yeah. And so we're in evolutionary terms, a lot of the variation in sleep environments that we're experiencing is very recent.
Michael: 30:37
Yes. So what happens when humans do the human thing and stretch boundaries, ask questions, go to new places, you know, do all this stuff, and then we spread out everywhere, and then we start living in all these places. And only recently have we have we really pushed those boundaries in the ways that we have. There are researchers at NASA study what happens on the Martian day.
Cressida: 31:00
Yes.
Michael: 31:00
Or what in spaceflight. Like, how do you first of all simulate the 24-hour day? Like all the movies show us simulating gravity, but which is very important. But so is the 24-hour rhythm to our entire physiology. Like, how do you well, how do you deal with this? So the story of humans in space is to some degree an extension of the story of humans in northern climates and southern climates and seasonal affective disorder, and you know, our bodies changing and reacting to being in a context we weren't designed for. We have lots of ways to adapt, but we just can't adapt that fast sometimes. There's occupations that are working non-24 hour days, like 26, 28, 30 hour days on like submarines and stuff, like some of those shifts. And like, and I'll see those guys as patients 30 years later still not able to sleep well.
Cressida: 32:05
So I mean, you're saying it's simply a biological impossibility that we could not sleep. Like what's the we've been talking about this in some of the other interviews. What are the edges of sleep?
Roxanne: 32:19
Great question. And that's been part of scientific study in different animals. It's been part of advanced interrogation techniques for different governments as they I don't want to say, well, I'll maybe I'll just say torture. that is a question h ans have explored in a variety of mediums. And I know there's a famous case, I think the Guinness World Record is hundreds, yeah, more than 200 hours of continued wakefulness. I was actually part of a grant in graduate school from DARPA, which is the department.
Cressida: 32:53
I was gonna say it's a military question.
Roxanne: 32:55
It's a military question. How can we get fighter pilots awake and not making errors for a week straight? So, how can we get a highly trained pilot able to fly for, I think this was a week at a time that they wanted without having the usual cognitive errors and emotional errors that that come with that degree of sleep deprivation. And most sleep scientists are like, that's not gonna happen, but we will gladly take some money and figure out what we can from this research. So one of the sort of the species exploration is what do animals that have incredibly hard migrations do? Right. So of these tiny little birds that fly over the ocean from the equator to the Arctic, right? How do they go for days and days without sleep? What's happening in their brain to be able to do that? Or or whales that, you know, sleep with half their brain at a time and alternate that. So the hemispheric sleep was a one mechanism. But my scientific belief is you're not going to be able to get humans to do that. It's it's just not possible. Like the animals that can do that don't have the inner connectivity between hemispheres that we do. They don't have like a super thick corpus callosum that connects one hemisphere with the other. I'm getting very technical, but I don't think we are going to be able to push humans to being able to stay up and be functional.
Joshua: 34:37
So at the end of that last clip, we hear Roxanne talking about some limits on how much we can adapt our sleep to some of the more extreme demands we might make of it.
Cressida: 34:46
Yeah, I was looking up the Guinness World Record for longest time without sleep the other day, and it's actually quite a bit longer than she says there. It's 453 hours, which is just under 19 days. It's a terrible thought, actually.
Joshua: 35:00
That is terrible.
Cressida: 35:00
Yeah. That record was set in 1986 and was still in effect in 1997 when Guinness stopped recording attempts, primarily due to increased understanding of the negative effects of prolonged sleep deprivation. So they did this with a bunch of different records as people became a bit more sensitized to the awful things that happened to people or the risks that people took by attempting them. So record holders or record attempters for the sleep one experienced not only acute fatigue and physical symptoms such as headaches and vomiting, a lot of vomiting, but also extreme cognitive symptoms, including delusion and hallucination. So there's a statement, I'll link to it in the show notes that Guinness made about this decision, and they point out that probably the record probably isn't very meaningful anyway, because most of the previous record holders who were monitored in an earlier phase of sleep medicine experienced micro sleeps, even as they appeared to remain awake. It's very difficult to tell if somebody's sleeping for seconds at a time, even if you're trying to keep them awake, explicitly, and that's likely true for all subjects of acute sleep deprivation, including voluntary polyphasic sleepers and victims of torture. So this micro sleeping phenomenon is what's just barely keeping people who are very acutely sleep deprived alive in a way that's not available to people who have who have fatal familial insomnia.
Joshua: 36:34
Yeah, and in these clips, we're really talking about how our basic, evolutionary, basic sleep needs to run up against some everyday experiences like shift work and some not so everyday experiences like going to the moon. And that these undercut that, you know, long history rest activity rhythm. And based on our conversation so far, you might think that our sleep needs are biologically fixed and that our cultures in the global north get in the way of them to various degrees, including going to space and leaving leaving the earth.
Cressida: 37:12
Just leaving the whole 24-hour thing behind.
Joshua: 37:15
Yeah. But we did an interview with a cultural psychologist who thinks that he's found some evidence that sleep health is dependent on the cultural fit of your sleep habits.
Cressida: 37:26
What so what does that mean?
Joshua: 37:28
Well, we start from the true claim that different cultures have different sleep practices, and one of those differences is sleep duration, so how long you sleep. And there are actually marked differences across national data on how long the average citizen sleeps. So if sleep is biologically inflexible, you might expect the shortest sleep duration context to show poorer health, but that doesn't seem to be the case.
Cressida: 37:54
Yeah, so cultural psychologist Steve Heine is doing a project that suggests that what determines your health outcomes is the degree of conformity to your culture's sleep norms, not the length of your sleep per se. It's a really counterintuitive conclusion. At one point he says, I'm sure this is going to provoke all sorts of objections, but interesting ones. He says there is no species-wide standard for sleep duration to optimize health. So
Cressida: 38:24
let's listen.
Steve: 38:40
My name is Steve Heine, and Im a cultural psychologist at the University of British Columbia. And I'm interested in how the cultures that we grow up in the shape of the ways that we think and act.
Cressida: 38:47
Great questions. So are we interested in that. So in your in that little intro, even you described your field of study as cultural psychology. So maybe you could just say what is cultural psychology and how did it lead you to an interest in sleep?
Steve: 39:01
Sure. Well, cultural psychology grew out of the field of psychology when we started to recognize that we don't just exist in this world by ourselves, but in many ways we're kind of plugged into a surrounding matrix of cultural meanings, of shared ideas about how we should be leading our lives. Every group of people comes to create a culture by sharing ideas with each other. You soon have shared norms and a shared reality, and that comes to influence the individual themselves. And so much of our psychology and our ways of of living then are shaped by what the surrounding culture informs us about how we should be living our lives and and how we should be thinking and and what is valued and and what is shunned. So I I've been interested in just seeing how much of our daily lives here are shaped by these cultural meanings that we learn from the people around us.
Cressida: 40:02
And how did it get you to sleep?
Steve: 40:04
Well, I I first got interested in this question about sleep and culture prior to starting grad school. I as an just after I graduated, got my undergrad from the University of Alberta, and I my first job was as an English teacher in a small town in Japan, in a junior high school there. And I would sometimes be out at night in this small town and I would run into my students, and it would be, you know, it's a it's a school night, and it would be about 10:30, and I would see a bunch of these 13-year-old students out, and I would go up to them and just thinking, wow, it's it's kind of late on a school night. And they would say, Oh no, we're just coming back from cram school now. And I thought, wow, yeah, that's pretty late. Well, you should go, you should get going to bed. And they would say, No, no, well, I have homework to do, I haven't eaten yet, or you know, some TV to watch. And and this was really bothering me for for many years. This was bothering me. And I started, I lived in Japan several years, and I started seeing this. That wasn't an exception at all. That was very much the the norm. And I would ask people, like, you know, what time did you go to bed? And aren't you tired? Because I would be, I would be, you know, exhausted if I was sleeping as little as all of my Japanese friends were around me. And and this had been bothering me for for for some time. And finally I decided, well, maybe I should do some research on this, because I from what I could tell, the the sleep research, the field of sleep research, at least haven't really tackled that question very well, I thought that it seemed like there's striking cultural differences in sleep, and that's puzzling because sleep is so important for our health.
Joshua: 41:47
So as you said at the end there, you've started working on this project looking at sleep duration and how that's maybe mediated across cultural differences. And as you point out in this research, the prior research shows two things. First, that not sleeping enough is bad for your health, and second, that how much people sleep is culturally variable. So in your sort of current research, you're testing for the inference that in cultures where sh sleep duration is the norm, that that should have a negative effect on health. Like can you tell us what what you found?
Steve: 42:27
Yeah, yeah, and just exactly as you said, it it would seem if short sleep durations are bad for our health, and in some countries people sleep much shorter sleep duration than others, it would seem that they should be suffering somehow from the the shorter sleep durations. at least on the surface, that would seem to be a conclusion one might draw. And as I was suggesting before, I've noticed that Japanese sleep don't sleep as much as many other places. And actually, this has been confirmed in a lot of other studies now that Japanese are the world champions for short sleeps. So what we decided to do, , we measured the sleep duration of adults in 20 different countries. we just asked people about whether typical sleep and what time they went to bed the previous night, what time they woke up. And we also asked them about their health. So they filled out some surveys where they answer questions about whatever kind of health conditions they might have and their subjective sense of health and and so on. And we thought, okay, if it's the case that short sleep durations are universally bad, then we should see these short sleeping countries such as Japan, that they should have more indication of these health problems than these longer sleeping countries such as well, France, Netherlands, Australia, New Zealand, and we didn't find any evidence for that. Really, a country's average sleep duration was unrelated to the average level in those countries of their health. Then we decided to look at the pattern within each country a little more closely. And we looked to see what was the sleep duration in each country that was associated with optimal health. That is, the healthiest people in our sample, how long were they sleeping compared to others? We did this in each country. And what we found is something that other studies have found as well is that when you look at, if you can imagine a graph where you have sleep duration on the bottom axis and health is on the the vertical axis, you tend to get a reverse U-shaped curve where people who are sleeping too little have lower health. But you also find this finding that's not discussed as much in the literature, but people who sleep too much, people sleep too much also tend to have report worse health. and so there's a sweet spot in the middle there, and that sweet spot indicates the sleep duration associated with optimal health. And what we found was that that optimal sleep duration varied significantly between countries. It wasn't the case that everywhere say that eight hours of sleep was associated with the best health. No, in each country it it was a different peak. The country's average sleep duration correlated with what was their optimal sleep duration. So in different places, people seem to need differing amounts of sleep, or at least the sleep that's associated with the the most health benefits seems to vary across countries.
Joshua: 45:42
And what's interesting there, I guess, is that like given what you're saying, if if you're in Canada, someone in Japan would seem to be sleeping too little, right? But to somebody in Japan, we Canadians might be sleeping too much. And as you say, like both are associated with negative health outcomes. So depending on where you are, you would say, oh, well, they're so they're so unhealthy, and they have all these negative health outcomes because they sleep too much or you know too little, depending on where you're looking from.
Steve: 46:16
Exactly. It seems that, you know, what our research suggests is there's not a universal standard, there's not like a species-wide standard that we need as a species, you know, that there's this one optimal sleep duration that if everyone would just adopt it, we'd all be be better off. it seems that our our sleep needs are more flexible than that. And what I think this suggests is that they're shaped by our cultural learning, that we kind of learn how to sleep a certain duration as we're growing up.
Joshua: 46:48
Interesting.
Cressida: 46:49
Yeah, I'm like the methodological challenges, Steve, of this work are so big, I think, in such interesting ways. And so I can see lots of lots of questions to ask about that. But it just thinking about like the range here is not, well, it's not that big in the sense that the average sleep duration for Japan, at least in one of your articles that you cited, is six hours and eighteen minutes out of every 24. And France, which was at the other end you said here, but also on that chart, those they're so louche, aren't they? The French, right? Seven hours and 52 minutes. So that's it is quite a big difference, 25%. But in a way, it's not as variable as other kinds of human practices. Like I don't know if you've seen, there's a famous book where the authors got people all over the world, families, households all over the world, to collect all of the food that they eat in a typical week and to stack it in front of them. So it's a visual representation of what and how much people eat. And the range is absolutely enormous. That's why it's a successful book. So I was thinking about that book and thinking about food, eating, nutrition as another really, really basic human need, like sleep. But the range of what people eat is I don't know how you really compare these apples and oranges, but it it seems to me that that's a much more culturally variable set of norms. And and sleep, there are certain parameters beyond which one can't go, and especially in terms of short sleep duration. So, how how do you explain how biology and culture are mediating each other here? Because we know that you can't chronic sleep deprivation is terrible for all humans, but what sleep deprivation means, at least your research is suggesting, is culturally mediated.
Steve: 48:52
Yeah, I agree that the the dietary practices very well might vary a lot more than sleep durations do around the world. The question with sleep is a little more challenging to figure out because it's the same logic we were talking about before. You know, well, if short sleep durations are bad, then yeah, these countries with the shorter sleep durations, we should see some evidence of this in people being impacted by this. And at least in in our studies and some other literature that we review, I don't think that evidence is so obvious. You you raise the question, well, how do we get, you know, what is the relation here between biology and and culture? And I think that's a really interesting question. And I think my perspective on this maybe differs, I think, somewhat from what medical researchers have have often thought on this, in that as a cultural psychologist, I see our species very much as a cultural species, that we need our cultures to survive. And everything we do is wrapped up in in cultural meanings. And I think this is also influences our biology. that I think the idea, which is I think quite common around the world is that our biology, you know, that's all the stuff, you know, inside my skin. You know, that's me, that's my biology, and the stuff outside my skin is is the culture, so that it's it's separate from us, so that we are these you know biological creatures, which you know, a clear boundary around our bodies or wrapped up in skin and we're interacting in this separate cultural world. I don't think that distinction is is really so clear-cut. So one, our genes, which are all in our body, and and what what our genes do is they express proteins to make us the way that we are, but our genes express proteins in response to many kinds of environmental stimuli. So, right away, just the basic mechanisms of how our bodies are made, it's in response to things happening in our environment. And so I think when you look across cultures and you start comparing biology to cross cultures, that's where you it starts to become a little more clear that this distinction between biology and culture isn't so clear-cut.
Joshua: 51:19
At the end, we get to the interesting conclusion that our basic bodily needs might be shaped by culture, and not only over the very long run of evolution, but in fairly immediate ways.
Cressida: 51:30
Yeah, so if we come back to where we started, we can see that the relationship between biology and culture when it comes to sleep might run in both directions. So our biology shapes the way we sleep and puts some limits on what's possible, for sure. But at the same time, our culture shapes the way we sleep in lots of ways that we've talked about many times. Everybody agrees so far. But if Steve's research comes good, and this is a project at a fairly early stage, I think, culture doesn't just stand in the way of sleep health, but might actually be its condition. So maybe what we were getting in talking to Michael and to Roxanne was more of a model in which biology provides a kind of foundation that there is, there are biological imperatives emerging from our evolutionary history that revolve around sleep and we just have to follow them. But that culture is somehow laid on the top, or it's somehow the kind of the force that acts in this case against biology, because most people are agreeing that our culture in the global north, which is not including, I think, Japan explicitly, but Japan seems to be an interesting kind of edge example here, is really not very good for our biological needs. But our biological needs somehow exist there underneath. If Steve's research comes good, then it's not just that our culture influences the way that we sleep, but that biology and our culture are mutually influencing each other in a way that determines something as basic as how much sleep you get determining your health, which seems like ought to be in that that category of biologically prior, you know?
Joshua: 53:23
Yeah, you've you've done a really good job putting those conversations into tension. And I noticed that you I noticed that you pressed Steve a little bit on whether there were any limits to his thesis, though we didn't have time to get fully into that.
Cressida: 53:37
Yeah, I mean, one question we might ask is whether people in Japan think that their sleep norms are good. And the answer is likely to be no. There's certainly plenty of Japanese people who think that the attitude that the culture takes to sleep is not a great one, just as within any culture there are people who deviate from its norms. But in the same way that I asked Roxanne, what are the edges of sleep? Like this is an interesting question. How far can you push sleep with a culture before things start to unravel? So what I was curious about with this example is whether maybe the Japanese had collectively hit on some kind of minimum sleep duration, six hours and eighteen minutes, below which things really would go awry. Like you can't, you couldn't be in a culture that didn't believe in sleep, because that's not possible.
Joshua: 54:28
There's a limit.
Cressida: 54:28
There's a limit, right? So what is this limit? And the idea that what counts as sleeping enough and not too much is not a single standard, is not in itself controversial because we know that different individuals require different sleep durations and even different individuals at different points in their life cycle. So the amount of sleep that you need when you're an infant is not the same as you need when you're 70, right? So it's that sort of idea of human variation in sleep duration is not controversial. But the idea that you are most likely to optimize your health if you stick closely to your culture's sleep norms is actually a pretty wild idea.
Joshua: 55:08
Right. And and that makes sense. In that context, Steve's comments about how culture doesn't end at the skin are provocative. Our sleeping bodies are being shaped by cultural practices all the way down in this sense. Maybe we can't overturn our evolutionary history the way that Michael Grandner describes it. But we shouldn't see culture as always operating as this like inconvenience to our biological imperatives.
Cressida: 55:34
Right. Yeah. I could keep going back and forth with this for a long time. Yeah.
Joshua: 55:40
It's a huge debate.
Cressida: 55:41
Yeah. However, we have to wrap things up for today. A reminder that part two of sleep science will be coming to you in two weeks. That's two weeks. And we'll talk about the social determinants of sleep health and what we might do about sleep injustice. So find out about the racial sleep gap, why sleep is a feminist issue, and why your teenager can't get up in the morning. There are even a couple of sleep tips. Yeah.
Joshua: 56:08
You can find all our episodes, show notes, and transcripts on our website, sleep is the new sex, all one word. Sleepisthenewsex.ca. Don't forget to follow and review. Thanks for listening.
Cressida: 56:20
This series is recorded at the University of Alberta, which is located on the territory of the Nehiyaw, Niisitapi, Metis, Nakota, Dene, Haudanosonee, and Anishinaabe, lands that are now known as part of Treaties 6, 7 and 8 and homeland of the Metis. As we talk about the history and meanings that sleep, rest, leisure, and productivity have for us, we also want to recognise the way each of these ideas participates in the history of colonialism that has shaped and continues to shape relations between settlers and First Nations. Our sound engineer is Tom Merklinger, who also wrote and performed our music. To find our first season, please see the link in the show notes. And for more information on this project, visit sleepisthenewsex.ca.
Roxanne: 57:15
I want to lean into that and just say tips. I don't want to say are so useless, but you can tips are what is used as the control. So for sleep studies, about how can we really improve, does this strategy improve sleep? The control condition that you don't expect to work is here's some sleep hygiene tips.
Cressida: 57:37
Right. Yes, exactly.