Matthew Wolf-Meyer Slumbering Masses

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.

Matthew Wolf-Meyer Biology of Everyday Life, Slumbering Masses

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…