Just as science was settling in on the “8-hours” hypothesis for ideal sleep, history intervened! According to a recent BBC report, Roger Ekirch, a historian at Virginia Tech, has found over 500 historical references to people sleeping in two four-hour shifts with a productive break in-between. With sources ranging from the Odyssey, to early modern Europe, to modern-day Nigeria, Ekirch found that many people may have slept in two chunks up until the past 200 years or so.
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.
This observation isn’t just one historian’s findings. There has been scientific evidence of this phenomenon for years, but it hasn’t gained traction because it seemed too far-fetched and formerly lacked historical grounding. On the science side:
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.
Like all great studies, this news forces us to reconsider the consensuses that the scientific community puts forth. Funny that here, the intervention was staged by someone in a tweed blazer with elbow-patches rather than a lab coat.