What’s a good night’s sleep – eight hours – or four hours twice?

If you wake in the middle of the night and can’t get back to sleep again – it could be good for you. There’s a growing body of evidence from both science and history that suggests that an eight-hour sleep may be unnatural.

In the 1990s, a psychiatrist named 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 time for their sleep to regulate but by the fourth week they had settled into a very distinct sleeping pattern. They slept first for four hours, and then woke for a few hours before falling into a second four-hour sleep.

Just after this, a historian at Virginia Tech published a paper, based on 16 years of research, revealing a wealth of historical evidence that humans used to sleep in two distinct sessions.

He found more than 500 references to a segmented sleeping pattern – in diaries, court records, medical books, literature, and from Homer’s Odyssey to an anthropological account of modern tribes in Nigeria. Just like the psychiatrist’s experiment, the 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.

What did people do during those middle hours?

Well it would seem they were quite active. They got up, visited neighbours, and even went to Church. Most people however stayed in bed, read, wrote and often prayed. And these hours weren’t entirely solitary – people often chatted to bed-fellows or had sex.

A doctor’s manual from 16th Century France even advised couples that the best time to conceive was not at the end of a long day’s labour but “after the first sleep”, when “they can have more enjoyment” and “do it better”.

Why did it disappear?

It seems that this first and second sleep pattern began to disappear during the late 17th century, starting with the wealthy urban classes of Western Europe, and filtering down across the next 200 years to the rest of Western society. By the 1920’s the idea of a first and second sleep had receded entirely from our social consciousness.

Another leading historian has put forward ideas of why this happened.

“Associations with night before the 17th Century were not good,” he says. “The night was a place populated by people of disrepute – criminals, prostitutes and drunks. Even the wealthy, who could afford candlelight, had better things to spend their money on. There was no prestige or social value associated with staying up all night.”

That changed following the Reformation and the counter-Reformation. Protestants and Catholics became accustomed to holding secret services at night, during periods of persecution. If earlier the night had belonged to reprobates, it was now the opposite. This trend migrated to various other groups, but in those days only for those who could afford to live by candlelight.

With the advent of street lighting, however, socialising at night began to filter down through the classes – and that happened sooner than you may think.

In 1667, Paris became the first city in the world to light its streets, using wax candles in glass lamps. It was followed by Lille in the same year and Amsterdam two years later, where a much more efficient oil-powered lamp was developed. London didn’t join their ranks until 1684 but by the end of the century, more than 50 of Europe’s major towns and cities were lit at night.

Enjoying the ‘Nightlife’ then became fashionable and spending hours lying in bed was considered a waste of time.

There was other strong evidence of this shifting attitude. It is even contained in a medical journal from 1829 that urged parents to force their children out of a pattern of first and second sleep.

Most people seem to have adapted well to the eight-hour sleep, but Ekirch believes many sleeping problems may have roots in the human body’s natural preference for segmented sleep and Russell Foster, a Professor of Circadian [body clock] Neuroscience at Oxford, shares this point of view.

“Many people wake up at night and panic,” he says. “I tell them that what they are experiencing is a throwback to the bi-modal sleep pattern.”

But the majority of doctors still fail to acknowledge that a consolidated eight-hour sleep may be unnatural.

Foster says: “Over 30% of the medical problems that doctors are faced with stem directly or indirectly from sleep or the lack of it. But sleep has been ignored in medical training and there are very few centres where sleep is studied.”

So the next time you wake up in the middle of the night, think of your pre-industrial ancestors and relax. Lying awake could be good for you. Maybe.

By John Redfern

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