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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.
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.
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.
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.
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."
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.
"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. |
