Edward Willett

Segmented sleep

[podcast]https://edwardwillett.com/wp-content/uploads//2012/02/Segmented-Sleep.mp3[/podcast]

It’s happened to all of us at one time or another: we wake up in the middle of the night, have trouble going back to sleep, start worrying about the fact we’re having trouble going back to sleep, start worrying about the fact we’re worrying about the fact we’re having trouble going back to sleep…and then the alarm goes off and we spend the rest of the day yawning.

Well, a February 22 news article by Stephanie Hegarty of the BBC World Service claims that both science and history suggest we should quit worrying and embrace our midnight wakefulness: that in fact, sleeping without waking for eight hours is an unnatural artifact of technological advances and something our ancestors would have thought extremely peculiar.

On the science side, Hegarty notes, about 20 years ago psychiatrist Thomas Wehr conducted an experiment that involved keeping a group of people in darkness 14 hours a day for a month. Not surprisingly, this disrupted their sleep: but by the fourth week, they’d settled into a new, stable pattern—not eight hours of uninterrupted sleep, but a four-hour sleep, an hour or two of wakefulness, and then another four-hour sleep.

On the historical side, there’s the research of  Roger Ekirch of Virginia Tech university, who in a 2001 paper and a 2005 book (At Day’s Close: Night in Times Past), discusses the more than 500 references he discovered, in everything from diaries to court records to medical books to Homer’s Odyssey, to a segmented sleeping pattern: a “first sleep” beginning about two hours after dusk, a waking period of an hour or two, and then a “second sleep”—exactly what Wehr observed in his subjects.

The references seem to indicate that this kind of sleeping was the norm.

Some people would get up and have a smoke or even visit neighbors during that waking period. Others would stay in bed, reading, writing or praying. (Prayer manuals from the late 1400s offer special prayers for the hours between sleeps.)

But Ekirch found fewer and fewer of these references going forward, until by the 1920s the notion of a first and second sleep seems to have disappeared.

He attributes that to improvements in domestic and street lighting. Better lighting at home made it more attractive to stay up late; street lighting made it more attractive to be out and about in the city. Businesses naturally took advantage of the change: coffee houses began to be open all night. There were simply more thing to do at night, and so the two-sleep pattern condensed into a single sleep.

As Hegarty puts it, “Night became fashionable and spending hours lying in bed was considered a waste of time.”

That sense of wasting time and losing efficiency became more pronounced as the industrial revolution took hold. Today of course, there are a million things to do no matter what the hour of the day or night…and millions of us are sleep-deprived as a result.

If sleeping the night through in one unbroken stretch is not entirely natural for humans, it could explain “sleep maintenance insomnia,” a condition where people wake up in the middle of the night and then have trouble getting back to sleep—and a condition that only shows up in scientific literature at the end of the 19th century, just as the concept of segmented sleep was beginning to disappear.

Hegerty quotes sleep psychologist Gregg Jacobs as saying, “For most of evolution we slept a certain way. Waking up during the night is part of normal human physiology.” He suggests the segmented sleep pattern we used to enjoy may have played an important role in regulating stress, since that hour or two in the night was spent in rest and relaxation.

So the next time you’re lying awake in bed in the middle of the night, don’t think of it as insomnia. Think of it as getting back to your roots.

If segmented sleep was good enough for your great-great-great-great-great-great-great-great-great-great-great-great-grandpappy, it ought to be good enough for you, too! And he didn’t even have the option of browsing the Internet at 3 a.m.

Poor guy.

 

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