The myth of the eight-hour sleep

 
Woman awake

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.

A woman tending to her husband in the middle of the night by Jan Saenredam, 1595 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.

Between segments

Grey owls

Some people:

  • Jog and take photographs
  • Practise yoga
  • Have dinner...

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 have more enjoyment" and "do it better".

Ekirch found that references to the first and second sleep started to disappear during the late 17th Century. This started among the urban upper classes in northern Europe and over the course of the next 200 years filtered down to the rest of Western society.

By the 1920s the idea of a first and second sleep had receded entirely from our social consciousness.

He attributes the initial shift to improvements in street lighting, domestic lighting and a surge in coffee houses - which were sometimes open all night. As the night became a place for legitimate activity and as that activity increased, the length of time people could dedicate to rest dwindled.

When segmented sleep was the norm

  • "He knew this, even in the horror with which he started from his first sleep, and threw up the window to dispel it by the presence of some object, beyond the room, which had not been, as it were, the witness of his dream." Charles Dickens, Barnaby Rudge (1840)
  • "Don Quixote followed nature, and being satisfied with his first sleep, did not solicit more. As for Sancho, he never wanted a second, for the first lasted him from night to morning." Miguel Cervantes, Don Quixote (1615)
  • "And at the wakening of your first sleepe You shall have a hott drinke made, And at the wakening of your next sleepe Your sorrowes will have a slake." Early English ballad, Old Robin of Portingale
  • The Tiv tribe in Nigeria employ the terms "first sleep" and "second sleep" to refer to specific periods of the night

Source: Roger Ekirch

In his new book, Evening's Empire, historian Craig Koslofsky puts forward an account of how 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 in the wake of 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, now respectable people became accustomed to exploiting the hours of darkness.

This trend migrated to the social sphere too, but 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.

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.

Street-lighting in Leipzig in 1702 A small city like Leipzig in central Germany employed 100 men to tend to 700 lamps

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.

Night became fashionable and spending hours lying in bed was considered a waste of time.

"People were becoming increasingly time-conscious and sensitive to efficiency, certainly before the 19th Century," says Roger Ekirch. "But the industrial revolution intensified that attitude by leaps and bounds."

Strong evidence of this shifting attitude is contained in a medical journal from 1829 which urged parents to force their children out of a pattern of first and second sleep.

"If no disease or accident there intervene, they will need no further repose than that obtained in their first sleep, which custom will have caused to terminate by itself just at the usual hour.

"And then, if they turn upon their ear to take a second nap, they will be taught to look upon it as an intemperance not at all redounding to their credit."

Stages of sleep

Every 60-100 minutes we go through a cycle of four stages of sleep

  • Stage 1 is a drowsy, relaxed state between being awake and sleeping - breathing slows, muscles relax, heart rate drops
  • Stage 2 is slightly deeper sleep - you may feel awake and this means that, on many nights, you may be asleep and not know it
  • Stage 3 and Stage 4, or Deep Sleep - it is very hard to wake up from Deep Sleep because this is when there is the lowest amount of activity in your body
  • After Deep Sleep, we go back to Stage 2 for a few minutes, and then enter Dream Sleep - also called REM (rapid eye movement) sleep - which, as its name suggests, is when you dream

In a full sleep cycle, a person goes through all the stages of sleep from one to four, then back down through stages three and two, before entering dream sleep

Source: Gregg Jacobs

Today, most people seem to have adapted quite 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 as well as the ubiquity of artificial light.

This could be the root of a condition called sleep maintenance insomnia, where people wake during the night and have trouble getting back to sleep, he suggests.

The condition first appears in literature at the end of the 19th Century, at the same time as accounts of segmented sleep disappear.

"For most of evolution we slept a certain way," says sleep psychologist Gregg Jacobs. "Waking up during the night is part of normal human physiology."

The idea that we must sleep in a consolidated block could be damaging, he says, if it makes people who wake up at night anxious, as this anxiety can itself prohibit sleeps and is likely to seep into waking life too.

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.

More from the Magazine

Margaret Thatcher caught napping, 1990
  • Margaret Thatcher was famously said to get by on four hours sleep a night
  • That put her in a group of just 1% of the population

"Over 30% of the medical problems that doctors are faced with stem directly or indirectly from sleep. But sleep has been ignored in medical training and there are very few centres where sleep is studied," he says.

Jacobs suggests that the waking period between sleeps, when people were forced into periods of rest and relaxation, could have played an important part in the human capacity to regulate stress naturally.

In many historic accounts, Ekirch found that people used the time to meditate on their dreams.

"Today we spend less time doing those things," says Dr Jacobs. "It's not a coincidence that, in modern life, the number of people who report anxiety, stress, depression, alcoholism and drug abuse has gone up."

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.

Craig Koslofsky and Russell Foster appeared on The Forum from the BBC World Service. Listen to the programme here.

Do you sleep in segments? Send us your sleep stories.

 

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  • rate this
    +18

    Comment number 21.

    Interesting relationship to the navy's 4-hour on 4-hour off watch pattern here. They don't seem to have any problem with 'fragmented' sleep doing it.

  • rate this
    +2

    Comment number 20.

    I remember as a soldier in Ulster in the 70's we slept a few hours at a time, 8 hours only happened on RNR, I used to forever feel hung over.
    At sea, where you are working at home in it's own right, afternoon siesta became a possible norm and that with about six hours at night was the best arrangement I've had!

  • rate this
    +2

    Comment number 19.

    I think sleep's a very personal thing. I've 2 kids of 5 & 7 yrs who both go to bed about 7.45pm. The 5yr old generally comes bounding through to wake me up around 6am while the 7yr old I'm generally still pulling out of bed around 8ish to go to school.

  • rate this
    +39

    Comment number 18.

    An illuminating article. I sleep in 4 hour batches and thought I was having sleep problems. I felt rested, but was sure I was debilitated from lack of sleep. Reading this article will make me more rested. Thank you.

  • rate this
    +1

    Comment number 17.

    I love sleep, its the best

  • rate this
    +79

    Comment number 16.

    "people often chatted to bed-fellows or had sex"

    I'll suggest this to my girlfriend next time i wake up at 3am, although i'm not sure the response will be favourable.

  • rate this
    +25

    Comment number 15.

    During basic military training I went for over a month with less than 4 hours sleep a night and one 55 hr session with no sleep at all. You can function well doing things you're trained to do but your judgement is seriously impaired. When I got home I slept for 26 hours without (apparently) dreaming or waking and couldn't work out how I'd lost a day. I suspect mental illness feels that way. Scary!

  • rate this
    +22

    Comment number 14.

    I find that the longer I sleep, ie near an 8 hr stint then the more tired I personally feel....... I have for a long time taken 4 or 6 hrs of sleep and do not need anymore....
    I'm 43, reasonably healthy (not an athelete), fun of energy and positive about everything regardless......

    I buy into this study and think being a little bit flexible in our sleep patterns is a GOOD thing..

  • rate this
    +7

    Comment number 13.

    I can imagine that long ago, when candlelight was all you had to see and read by, and even then was too expensive for most people (and there were no spectacles either) there used to be little you could do except go to bed in the dark. Therefore you would tend to awake during the night. Remember when a powercut hit NY city and everyone went to bed early...the conception rate shot up!

  • rate this
    +24

    Comment number 12.

    Support for the afternoon Siesta?

    I find that dividing up my work periods feels quite natural,

  • rate this
    +1

    Comment number 11.

    am 18 and usually sleep for a couple of hours at a time, still feel refreshed in the morning even after only two hours sleep

  • rate this
    0

    Comment number 10.

    Interesting - when I'm stressed at work I often can't get back to sleep in the night when I awake - and if it's at the 4 hour point that is usually fatal. I guess that's corresponding possibly to having a tendency to be more awake at that point.

  • rate this
    +5

    Comment number 9.

    A short "power nap" of 10-20 minutes in the afternoon works wonders for me. When I was in the office I used to go and sit in the car (on warm days!) for this. Set my phone to wake me up!
    The amount of sleep you need is a very personal thing.

  • rate this
    0

    Comment number 8.

    Yes its good news always a light sleeping. Am 55 now and rarely get more than five six hours.

  • rate this
    +33

    Comment number 7.

    Excellent. Double sleep means double breakfast, no?

  • rate this
    +10

    Comment number 6.

    Two eight-hour chunks per night would suit me fine!

  • rate this
    +45

    Comment number 5.

    I don't think it is natural to be awake for 16 hours straight then sleep solidly for 8 hours. I think it is natural to have naps in the daytime and would relish the provision of a napping area at work. Currently, I am so tired by mid-afternoon, I have to go the toilets in my office, and have a 20 minutes kip in a cubicle, otherwise I would literally be falling asleep at my desk.

  • rate this
    +13

    Comment number 4.

    "Stage 2 is slightly deeper sleep - you may feel awake and this means that, on many nights, you may be asleep and not know it " - hence why I am accused of snoring when I don't hear it and feel that I am awake.

  • Comment number 3.

    All this user's posts have been removed.Why?

  • rate this
    +12

    Comment number 2.

    I suffer with a prostate problem so I regularly go to the loo at least once during the night. I have done this for years now without any problems of feeling sleepy during the day. That period between sleeps is a wonderful time to solve problems; I suspect it is because the brain does not have to deal with functions such as balance while in a comfortable, warm, protrate position.

 

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