Ok, maybe your grandparents probably slept like you. And your great, great-grandparents. But once you go back before the 1800s, sleep starts to look a lot different. Your ancestors slept in a way that modern sleepers would find bizarre – they slept twice. And so can you.
The existence of our sleeping twice per night was first uncovered by Roger Ekirch, professor of History at Virginia Tech.
His research found that we didn’t always sleep in one eight hour chunk. We used to sleep in two shorter periods, over a longer range of night. This range was about 12 hours long, and began with a sleep of three to four hours, wakefulness of two to three hours, then sleep again until morning.
References are scattered throughout literature, court documents, personal papers, and the ephemera of the past. What is surprising is not that people slept in two sessions, but that the concept was so incredibly common. Two-piece sleeping was the standard, accepted way to sleep.
“It’s not just the number of references – it is the way they refer to it, as if it was common knowledge,”
Two sleeps per night may have been the method of antiquity, but tendencies towards it still linger in modern man. There could be an innate biological preference for two sleeps, given the right circumstances.
In the early ‘90s, psychiatrist Thomas Wehr of National Institutes of Mental Health conducted a study on photoperiodicity (exposure to light), and its effect on sleep patterns.
In his study, fifteen men spent four weeks with their daylight artificially restricted. Rather than staying up and active the usual sixteen hours per day, they would stay up only ten. The other fourteen hours they would be in a closed, dark room, where they would rest or sleep as much as possible. This mimics the days in mid-winter, with short daylight and long nights.
At first, the participants would sleep huge stretches of time, likely making up for sleep debt that’s common among modern people. Once they had caught up on their sleep though, a strange thing started to happen.
They began to have two sleeps.'
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Just Plain Nuts.