Insomnia? Or Evolution?

Here’s the latest for Psychology Today:

Something woke you up in the middle of the night. The tug of the need to urinate? A bedpartner’s jerky limb? A loud noise? A startling dream? Whatever it was, the event passes as you bring yourself to unsteady consciousness. You lay in the dark for a few minutes — for what seems like a few minutes — deciding whether or not you’re going to get out of bed, if even to go to the bathroom quickly. After another minute of laying in the dark, your bladder has convinced you to go to the bathroom — maybe then you’ll be able to get back to sleep. But once you’re in the bathroom, you know it’s all over. You’re awake. You hadn’t even turned on the lights for fear that doing so would make returning to sleep impossible, but as you fumble in the dark, you know that night has come to an end and your day is starting very early.

The experience is generally referred to as sleep maintenance insomnia. It is characterized by being able to fall asleep when one wants to, but awakening in the middle of the night and being unable to get back to sleep. According to the National Sleep Foundation and drug manufacturers, millions of Americans experience sleep maintenance insomnia on a regular basis. From the perspective of modern science and medicine — and society more generally — this is disorderly sleep. If you wake up after four hours and stay up until the following night, you aren’t getting the amount of sleep you need in order to get through the day. Yet from the perspective of history, being unable to get back to sleep immediately might have everything to do with human evolution.

Humans may have evolved to sleep in a biphasic or non-consolidated fashion, that is, we may be physiologically inclined to sleep in two or more periods over the 24-hour day. We have unambiguous evidence that in pre-industrial Britain and the United States — so before 1840 — that people slept in two periods at night. They would lay down to sleep around sunset or shortly thereafter, wake up around four hours later for a couple of hours, and then sleep again for a few more hours. Today, despite pressures to stop doing so from some quarters, napping cultures thrive in southern Europe, China, Taiwan and elsewhere — people sleep for several hours at night and supplement this sleep with a hefty nap during the day, upwards of two hours.

Sleep is comprised of a series of cycles, which last about two hours for most people. During each cycle, we move through non-Rapid Eye Movement and Rapid Eye Movement (REM) sleep. At the end of each cycle, we move towards wakefulness, and this is when people often wake up. When we wake up in the middle of a cycle — due to an alarm clock or emergency — we often feel terrible throughout the day, struggling with an unresolved sleep cycle. (Incidentally, there are now alarm clocks that detect your progression through a sleep cycle and wake you up at just the right time.) When we think about this from the perspective of evolution, waking up every couple of hours to check your environment is a pretty useful adaptation — sleeping deeply through the night puts one at risk of nocturnal predators. But modern society favors consolidated sleep, so those of us who still sleep as our ancestors did are at risk of being diagnosed with sleep maintenance insomnia.

There aren’t any drawbacks to sleeping in a less consolidated fashion. Some evidence suggests that the grogginess we experience upon awakening is lessened and that we wake up more easily when we sleep for shorter periods. But society is structured around consolidated sleep — as I discuss in The Slumbering Masses, very few employers offer onsite napping facilities — and spending 12 to 14 hours in bed each night would cut into work and family time. And so, even though biphasic sleep might work for us physiologically, it might not work so well socially.

This is why sleep maintenance insomnia is treated as a sleep disorder and not normal human variation: it’s disruptive to society. It can be a nuisance to individuals as well — being chronically sleep-deprived can lead to serious social and health problems — but it wouldn’t be such a nuisance to individuals if society was set up to allow for people to sleep the ways they want to. American sleep patterns are more indebted to our ideas about the workday and school day than any basis in human nature or evolution. Some sleep disorders are serious and benefit from medical attention. But people who experience sleep maintenance insomnia might benefit more from a midday nap than a pharmaceutical fix or a large coffee. It’s up to us all to think about how society might better reflect our needs for sleep — to invent social arrangements that benefit us rather than pharmaceutical companies and the corner Starbucks.

But I’m Not Sleepy!

Here’s the second Psychology Today blog post:

One of my strongest memories from high school is the feeling of that extra hour of sleep when we fall back into standard time each autumn. After the first few weeks of school, and the mounting sleep debt of having to wake up at too early of an hour, having that extra hour of sleep felt exquisite. But the eventual transition back to Daylight Saving Time in the spring was excruciating. Losing that hour of sleep made school much more difficult – at least until my urge to sleep aligned with Daylight Saving Time. My circadian rhythm was generally not the same as the one that I needed to get through the school day without feeling sleepy. This situation made very apparent to me that it’s arbitrary when we start school and work, and that my need for sleep was often at odds with those decisions.

Our circadian rhythms are the result of complex interactions between our body and our environment, and are generally seen as the force that cues us to feel sleepy. On one side, we have the urge to be awake. On the other, the need to sleep. When one overtakes the other, sleep or wakefulness ensues. As we sleep, the need to sleep reduces, and our alerting functions take over – until the need for sleep builds up again and we head for bed. Scientists have suggested that circadian rhythms govern much more than our need for sleep, including our urge to defecate and our appetites. We can delay our need for sleep – or eating or defecating – temporarily, but we can’t defer it indefinitely.

In his book, The Promise of Sleep, William Dement recounts the case of Randy Gardner who stayed awake for eleven days – but we now know that anyone who stays up for too long starts to microsleep as their need for sleep forces them to rest, even while their eyes might be open. As much as we might fight it, our circadian rhythm shapes our sleep.

Many people would tell you that our circadian rhythms are innately tied to the environments we’ve evolved in, but that’s not strictly true. Over the millennia that humans have evolved, they’ve inhabited a number of diverse environments around the globe, all with their own light cues – in circumpolar regions, humans have lived in periods of prolonged night and day; in equatorial regions, humans have been exposed to roughly equal periods of night and day. Sleep, in both of these environments – and all of the environments in-between – has developed as both a social and biological response to these cues. We sleep when we’re tired, but we also tend to take to our beds when the nights are long and we have limited light and heat. This has resulted in a wide variety of sleeping schedules – from societies that favor a midday nap to those that favor a long night in bed. And, then there’s the United States, that tends to favor a short night in bed – eight hours or less – and no midday nap, except for the very young and the very old.

If you were to measure the circadian rhythms of people throughout the world, you should find that there are a wide variety of expressions of circadian cues. But when we look at the science of sleep, one representation of circadian rhythms prevails, and it often looks like this – which I’ve borrowed from Dement’s Promise of Sleep, and which I talk about extensively in my book, The Slumbering Masses:

This model is based on individuals sleeping for eight hours at night – from 10 p.m. until 6 a.m. But what if that individual took a nap in the middle of the day? Her sleep need would decrease accordingly and start to rise again. At bedtime, her sleep need would be less, but still enough to get to sleep. Or, if she slept in two four-hour blocks throughout the day, the need would be more balanced, and never so great that her urge overtakes her need – she wouldn’t just spontaneously fall asleep while in a meeting or driving home.

If we consistently slept in different patterns, our circadian rhythms would look quite different – both because of how we slept, but also because of other environmental cues, like food and light. Humans have evolved to have flexible circadian rhythms, and beyond just patterning of sleep shaping our rhythms, our exposure to light and our consumption of food shape our urges for sleep. This is one of the keys to understanding jetlag: when we go from one set of environmental cues to another, our bodies often react negatively, with our cues for sleep being mismatched to environmental cues. Only after we adjust to the new patterning of light and food intake do we begin to adjust to the new time zone, and our sleep follows suit. This can take a while, in part because our adjustment to food intake can be rather slow, whereas light impacts us quite quickly. Adjusting to Daylight Saving Time is often no big deal, because it’s a slight variance in time and we adjust our schedules accordingly. But adjusting to a bigger time difference – a few hours or more – can often leave us with a serve sense of being dislocated in time.

Despite the relative flexibility and variation of circadian rhythms, the models we have of our biological cues are fairly rigid and are based on the assumption of nightly consolidated sleep and large meals throughout the day. If we slept in two four-hour blocks, or one nightly block supplemented with a daily nap, our rhythms would alter. If we ate smaller meals throughout the day as well, our rhythms would again look less dramatic in their highs and lows. But such an organization of sleep and eating would depend on us investing in a much different ordering of society. The result would both be a dramatically different experience of sleep for us – as individuals and as members of society. And it would change how we conceive of normal and pathological sleep. What we now think of as sleep disorders – narcolepsy, insomnia, shift work sleep disorder – might not be so pernicious and in need of medical treatment.

But changing society to ease our discomforts around sleep seems unlikely – if it’s ever going to happen, it’s going to depend on denaturalizing our conceptions of human circadian rhythms and to take seriously how other orderings or society might benefit our biological experiences of ourselves and the world.

How Natural is Human Sleep?

Here’s the first of the blog entries for Psychology Today:

You’re sitting at your desk, slowly reading through your response to a friend’s email, when you feel the sudden tug of sleepiness. The next thing you know, you’re waking up with your head on the desk, your hands folded under you in a makeshift pillow. Or, your riding on the train, playing a game on your iPhone, when the next thing you know you’re waking up and reaching under your seat to fish for your phone. You haven’t been napping long, so hopefully nobody noticed. Maybe it’s just incidental sleepiness – you haven’t been sleeping well lately – but it happens with more and more regularity. Maybe it’s time to see a doctor about it?

Over the last decade or so, Americans have become more and more aware of sleep and its disorders. One way to think about this change in public awareness is that it’s due to the new recognition of sleep disorders – that science has discovered new pathologies, their causes and cures. This might appear to be the case with narcolepsy, the sudden onset of sleep, often associated with momentary heightened emotions, which has been diagnosed more commonly since the 1970s. In fact, we’ve had a reasonably well-articulated sense of narcolepsy since the 1820s, thanks to Scottish physician Robert Macnish, who described it as ‘drowsiness’ in his Philosophy of Sleep. We still don’t really know what causes narcolepsy, but we do have treatments for it that are reasonably well tolerated by narcoleptics. And this might be the reason why we’re paying so much more attention to sleep these days: changes in pharmaceuticals. But that’s not strictly true either, since throughout history we’ve have suitable if not wholly effective treatments for a number of sleep disorders – we just prefer pharmaceuticals to changes in lifestyle these days. Rather, our heightened interest in sleep has everything to do with our disconnection from history and the many changes that American sleep and society have gone through over the last two centuries, which make a lot of phenomena seem new, when we’ve been living with them for centuries.

About a year ago, I was on a conference panel with a laboratory scientist who specializes in developing technology for the assessment of sleep disorders; he gave a presentation on the state of the art in sleep science and medicine, a talk designed for his audience, which was largely comprised of scholars in the humanities and social sciences. Meanwhile, I gave a presentation focused on a minor event in the history of sleep science, an experiment led by Nathaniel Kleitman — then a professor of physiology at the University of Chicago — aboard a U.S. Navy submarine to ascertain the ideal arrangement of sleep while at sea – which I discuss in my book, The Slumbering Masses: Sleep, Medicine & Modern American Life. During the question and answer period, an audience member asked my co-panelist about changes in scientific conceptions of sleep, to which he answered – and I’m paraphrasing here – ‘That’s not my job, it’s yours.’

I’ve heard similar sentiments from scientists and physicians before – they’re busy on the frontline, dealing with the demands of patients, writing grants, and conducting their own research, and don’t have the time to do investigative social research. At one conference where I was talking about the history of the sleepwalking defense for murder cases in the U.S., I saw more audience members – scientists, physicians and other medical professionals – take more notes on my quick discussion of the history of narcolepsy than on the changing conceptions of intent in American law, both of which, I was attempting to convince my audience, you can’t fully appreciate without understanding the U.S. in the 19th century.

Although social scientists are sometimes seen as lobbying groundless critiques at laboratory scientists, one of the things that social scientists are especially good at is debunking things that we’ve come to accept as natural. This process is often referred to as denaturalization – showing how what we take to be natural is the result of a history of human action that has moved something from being understood as social to natural. One of the cases I discuss at length in my book is that of consolidated sleep in the U. S. The eight hours of sleep so many of us seek out each night is not based in nature, but instead is the invention of many doctors, scientists, and business owners, and began in the 19th century to only be fully realized in the 20th.

Previous to the mid-1800s, many Americans slept in what’s referred to as biphasic fashion. That is, they would fall asleep around dusk, wake up a few hours later for a couple hours, and then sleep for a few more hours before waking around sunrise. Or, they would sleep for a few hours at night and a few more during the day. We have evidence of this in England, thanks to historian Roger Ekirch, and, as I discuss in The Slumbering Masses, American medical literature in the 19th century is full of references to these kinds of sleep patterns. When you think about it, our nights are often much longer than eight hours, so even if our sleep is determined by our environments, we would assume that humans would sleep much more than they do; instead, humans need less than a full night’s sleep as reckoned by the sun. We need somewhere between 6-10 hours each night, a figure that changes over the life course, with children and adolescents needing more and the elderly needing less. How we manage to get that sleep is up to us, or, rather, it’s often up to social norms.

In the U.S., we tend to prefer nightly, consolidated sleep – eight straight hours, with no nap during the day. For preschoolers it might be different, with longer nightly sleep and naps to boot. But, elsewhere and over the course of history, sleep arrangements have been different. In their efforts to understand biological phenomena, scientists can sometimes substitute what they believe for scientifically deduced fact. This is the case with American models of sleep, where early researchers in the 20th century used the consolidated model of nightly sleep for the basis of their scientific research (which I discuss in Chapter 2 of The Slumbering Masses). If they had used different models – say models that favor biphasic sleep – contemporary sleep science and medicine might look a lot different than they currently do.

Social scientists then, and cultural anthropologists especially, work hard to denature the facts that have come to be taken for granted – by scientists and the public. Critique of this sort is important for a number of reasons. First, it serves as a corrective when beliefs come to be taken as facts. Secondly, it opens up science to be a dialogue. When science is only happening in labs, it’s liable to be susceptible to the biases of researchers and the expediencies of grants, publication and promotion – hence the recent increased awareness about the prevalence of fraud in scientific publishing. And, most importantly, it infuses science with the lived experiences of individuals – which is why we do science in the first place: to make our individual and collective lives better. So when we take scientific fact as the basis of our lives – whether it be something we read on the internet or a pill we’re prescribed – we should always consider whether it helps us make sense of our life. And if it doesn’t, we should keep looking for answers. Some of those answers might be found in history or in other societies, where we might come to see that our sleep hasn’t always been what it is or that we might arrange our days and nights differently. This isn’t so much debunking science as helping bring it to life.

On the Evolution of Sleep

This was originally posted over at the UMN press blog.

Have humans evolved to sleep in a consolidated, nightly fashion, or is this some kind of social construct that we’ve fallen into? There’s a nice write up on the evolution of diurnal behavior in humans by Cris Campbell, in which he uses my recent article in Current Anthropology to think about the relationships between economy, society and sleep. I’m no hardline social constructionist by any means, but I’m sometimes concerned that evolutionary approaches to sleep can be fairly reductive. And one of the dangers of being biologically – and naturally reductive – is that we can come to accept things like American capitalism as the natural outgrowth of a particular pattern of human behavior, which I write about extensively in The Slumbering Masses. Some kind of middle road between biology and society is necessary to really see how sleep is being shaped by social demands and how it impacts our biological well-being. It sounds so reasonable, but it can come across as a little radical when I tell people that there’s no absolute human nature that determines our individual and collective actions, which is the basis of my argument in that Current Anthropology piece.

Rather than thinking of nature and nurture as absolute determinants of our behavior, it’s more appropriate to think of any individual behavior or social form as existing on a continuum between nature and nurture. That is, everything is somewhat natural and somewhat cultural (and sometimes what we say is natural is actually cultural). And sleep is a great example of this: yes, we all have a natural, physiological urge to sleep, but how each person – and each society – organizes sleep varies, based on cultural norms and individual preferences. For some, this can mean nightly, consolidated sleep in an eight-hour chunk; for others, it might mean biphasic sleep – breaking sleep into two (or more) blocks of sleep, arranged throughout the 24-hour day. So our sleep styles may have developed out of evolutionary selection, or it might be a little more complicated.

Biological anthropologists agree that niche construction can often interfere with (for better or worse) the process of evolution. Roughly, they mean that organisms of all sorts (including humans) can change their environments to maximize the possibility of their survival – think beavers building dams, which changes the local ecology both for the beavers, as well as for the other animals, insects and plants that are part of that environment. Humans, the usual argument goes, are niche constructors without parallel, having built complex societies, agricultural infrastructure, and cities. The assumption in much of the niche construction literature is that niches are positive – at least for the constructor. But humans may be able to build niches that are actually unhealthy for us. If humans evolved to be biphasic sleepers, our pattern of consolidated activity throughout the day may be a very good example of a niche gone wrong.

The niche that Americans have built, slowly over the last 200 years, as I talk about in The Slumbering Masses, is one that consolidates our daily activities into one block in the day (say the 9 to 5 work schedule, alongside the 8 to 3 school schedule), followed by a period of recreation – usually taken up by dinner and nightly television – to be followed by our consolidated sleep. All of which begins again the following day, unless it’s the weekend. This kind of niche isn’t a byproduct of some inner nature, but rather a piecemeal construction that we’ve invested in over centuries of social development. And, if we look elsewhere, there are other models – including societies that favor biphasic or daytime sleep.

If we’ve developed a social structure based on our evolutionary desires for sleep, we could expect to generally not feel sleepy throughout the day and rarely see cases of insomnia. Since 30-40% of Americans claim to experience insomnia symptoms with some regularity, and there’s a booming industry in alertness-promoting chemicals (drugs like Provigil, coffee, soda, tea, energy drinks, etc.), it would seem like our niche doesn’t really meet our needs. At its most benign, it might mean that we consume more caffeine than we should; but it might also be that the niche we’ve built is incredibly difficult for many to conform to, leading to experiences of sleep disorders.

There’s at least two dangers in assuming that our contemporary social structure is based on our evolutionary preferences. First, like I mentioned above, it naturalizes things like capitalism as inevitable outcomes of our selected-for behavior, which I discuss in that Current Anthropology article, as well as in The Slumbering Masses. Secondly, it means that disorderly sleepers aren’t just pathological and in need of treatment, but evolutionary aberrations or throwbacks. That might sound a little silly, but similar ideas have been the basis for racism throughout history; as genomics provides a basis for our understandings of ourselves and others, we may also be facing a future of gene-based discrimination, not entirely different from Aldous Huxley’s Brave New World (which I also mention in that Current Anthropology piece).

Now, it may be that through this niche construction, we’re slowly selecting against people who don’t sleep in accordance with it — but with such a large, complex society, that’s unlikely to happen. One of the neurologists I know once said that our brains work best with a cup of coffee in our system. It’s a strange fantasy to imagine that we evolved over time through the selection of individuals who respond well to caffeine. Rather, it’s an accidental correlation between our physiologies and our lifestyles that leads us to really thrive on caffeine (for those of us that do).

It’s a lot safer to recognize that evolution isn’t purposeful in all of its selections; some selections are accidents, although they can be beneficial. What we can select are the social models that govern our lives, and other models are possible, as organizations like the Take Back Your Time movement have advocated for. And what we should be working towards are social forms that meet the needs of all sleepers, not some or even most. Recognizing that society can be different – and more flexible – also accepts that variation within the human species is non-pathological, and that there might be better ways to think about difference than as disorderly.

Time is Alien, or Why I Slept through High School

I keep this old issue of Worlds of Tomorrow (an old pulp magazine) in my office with a nice article from Robert M. W. Dixon about the relative nature of number. He imagines what a species with six fingers on each hand might do with counting, and proposes that they would develop a number system with less weight on 5, 10, and 100 and more on 6, 12, and 144. His argument is that given a different physiology, a species might develop a radically different number system, and that there’s no real natural basis to number — an argument pretty similar to Brian Rotman’s, Helen Verran’s and Stephen Chrisomalis’ work. Time, like number, is a social invention, and given different environmental conditions, we might have a very different system of time. Like Stan Robinson’s Mars Trilogy, the day on Mars is necessarily going to be ordered differently than the day on Earth. Our day is measurable and predictable, but it doesn’t necessarily fit in well with our calendar system (hence the need for Leap Days).

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There’s a nice piece in the New York Times Magazine from about a week ago that reviews a new book about chronobiology and the frictions that society produces for individuals. One of the points that both the book and article authors make is that individual clocks vary significantly from one another and over the life course — so the same person has radically different sleep needs at infancy, through childhood, during adolescence, young adulthood, and so on. And, added to that, are the clocks of those around us — those we share beds with and care for, which I talk about at length in The Slumbering Masses. The problem that so many of us face, especially during our teen years, is that our clocks are radically at odds with the institutions that shape our lives, especially school.

The debates around changing school start times have been going on for a long time now, and the evidence seems pretty compelling. Scientists can show that our cues for sleep tend to move later in the day and our need for sleep is longer, e.g. during your teens you might not be able to fall asleep until 11 PM and you might need 9 hours of sleep, making an 8 AM (or earlier) school time especially difficult to make. As a result, students end up falling asleep in class, have short attention spans, consume too much sugar and caffeine, act testy, and perform poorly in their school work. The schools that have recognized this have started to move school days later for middle and high schoolers, and have moved the school day up for elementary schoolers (who tend to wake up early). Unfortunately, there’s still a lot of resistance to changing school time, and it has a lot to do with social uses of time.

Parents tend to want to have earlier school days for their children, to ensure that they’re watched while parents work. And they don’t want buses to interfere with their morning commutes. Meanwhile, sports teams prefer to practice at the end of the school day, but want day light in order to conduct themselves. As a result, the school day remains relatively static, continuing to ensure that many students are chronically sleep deprived.

Our internal clocks tend to be rather stable within each life stage,* and so are our social cues (e.g. work starts at 9 AM or school at 7:15). But when we’re chronically sleep deprived, we tend towards earlier sleep throughout the week. And if we have social obligations blocking our ability to sleep — child or elder care, take-home work, chores — our sleep debt grows and grows. As a result, we crash and catch up on the weekends, only to start the whole cycle over again the following week. We pay off our debt only to build it up again — a nice synecdoche for American life more generally. And, sometimes, we end up seeing doctors for our sleep complaints, which can result in being prescribed a medication for problems that are largely socially determined – which I write about everywhere.

There are two solutions to these problems: First, our policy makers need to spend a little more time talking to scientists and physicians (and the occasional social scientist), and to take what they have to say about our biological drives more seriously when it comes to instituting social times. And, more importantly, our institutions need to be made more flexible. I think back on my time in high school, and I know some of my teachers didn’t want to be there at 8 AM any more than I did. Why not have a staggered school day, and allow students to start at 10 AM and end at 4 PM, or 7 AM and end at 1 PM? Flexibility like this would attend to the broad variation of physiological and social experiences, and help minimize our negative reactions to the requirements of everyday life. And it might just help us sleep better at night — or whenever the urge hits us. After all, there’s nothing strictly natural about our everyday schedules — they could be ordered radically differently — but it’s up to us to re-imagine the possibilities.

* I’ll write more about ways to change your clock some other time — it all has to do with your liver…