The myth of the eight-hour sleep
We often worry about lying awake in
the middle of the night - but it could be good for you. A growing body of
evidence from both science and history suggests that the eight-hour sleep may be
unnatural.
In the early 1990s, psychiatrist Thomas Wehr conducted an experiment in which
a group of people were plunged into darkness for 14 hours every day for a month.
It took some time for their sleep to regulate but by the fourth week the subjects had settled into a very distinct sleeping pattern. They slept first for four hours, then woke for one or two hours before falling into a second four-hour sleep.
Though sleep scientists were impressed by the study, among the general public the idea that we must sleep for eight consecutive hours persists.
In 2001, historian Roger Ekirch of Virginia Tech published a seminal paper, drawn from 16 years of research, revealing a wealth of historical evidence that humans used to sleep in two distinct chunks.
Roger Ekirch says this 1595 engraving by Jan
Saenredam is evidence of activity at night
His book At Day's Close: Night in Times Past, published four years later,
unearths more than 500 references to a segmented sleeping pattern - in diaries,
court records, medical books and literature, from Homer's Odyssey to an
anthropological account of modern tribes in Nigeria. Much like the experience of Wehr's subjects, these references describe a first sleep which began about two hours after dusk, followed by waking period of one or two hours and then a second sleep.
"It's not just the number of references - it is the way they refer to it, as if it was common knowledge," Ekirch says.
During this waking period people were quite active. They often got up, went to the toilet or smoked tobacco and some even visited neighbours. Most people stayed in bed, read, wrote and often prayed. Countless prayer manuals from the late 15th Century offered special prayers for the hours in between sleeps.
And these hours weren't entirely solitary - people often chatted to bed-fellows or had sex.
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