An Evolutionary View of Humans 2: Sleep

Efe people
Ituri Forest
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There has been much recent discussion on sleep in the blogosphere, and everyone, especially those who sometimes have trouble sleeping, is interested in so called “sleep disorders.”

My understanding of modern sleep disorder theory is the following (very oversimplified): Each person has a “normal” amount of sleep that they seem to need each night. “Better” sleep is uninterrupted. You will feel lousy if you don’t get your sleep. However, if you miss the “normal” amount of sleep several nights in a row, you only need one “good night’s sleep” to totally readjust and get back to feeling normal again. (You don’t have to make up all the hours you missed … heavens, there IS a free lunch!)

Even the critical medical anthropologists are getting into this. I need to be careful here, because this involves my colleagues down the hall… one of our graduate students, Matt Wolf-Meyer, is working on this issue.

Matt happens to be a really smart guy and I’m sure he’ll do ground breaking research, but this critical (as in it is a critique) research seems to fall into the same little trap that the traditional medical work falls into: It ignores what we know about hunter gatherers.

Here’s the scoop. (Everything I say here and everywhere else about foragers does not apply to Australia. Remember that.) Foragers live in flimsy dwellings (or no dwelling on some nights) clustered tightly together, so, for instance if one person snores everybody hears it (though snoring is rare among foragers in my experience). My point is simply that everyone is physically close.

Even in warm areas, it gets cold at night, so there are fires. Fires have the upside of making you warm, but a couple of downsides as well. First, they need to be tended frequently. Second, adults and especially children can fall or roll into them and get badly burned.

A typical night with the Efe is, I strongly suspect, typical of any night with any tropical or subtropical forager group. At any given moment in time, somebody is asleep and somebody is awake. Those who are awake are often talking. Sometimes they are talking to each other, but often they are just talking. Telling a story that someone may or may not be interested in. I suspect that part of the constant noise making (and what may make Africa different from Australia) is that you don’t want to be too quiet for too long else wandering dangerous animals …. a leopard, a suid, an elephant … may stumble into your camp and cause trouble.

The person or persons who is/are awake shifts throughout then night. It is not systematic … people are not really keeping watch … it just seems to happen. Individuals sleep when they are comfortable, and become uncomfortable as the fire cools, wake up, adjust the fire, and either stay up for a while or fall back to sleep. If one child is keeping his or her family awake, this affects the entire group. And so on.

Naps during the day (as you might expect since everybody gets a poor night’s sleep by Western standards every night) are common.

Here it is in a nutshell. The Efe, and I again suspect this is typical for foragers, spend the entire 24 hour cycle sometimes awake and sometimes asleep. During the night, “asleep” is more common than “awake” and during the day “awake” is more common than “asleep.” To foragers, it’s all napping.

One could criticize this description by pointing out how it conflicts with modern medical views of sleep. But you would be wrong. It is the case that modern medical views of sleep need to be adjusted to take into account the realties of what humans have probably always done for hundreds of thousands of years (since the first control of fire, perhaps).

NEXT INSTALLMENT: An Evolutionary View of Humans 3: Remembering Names

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