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The myth of the eight-hour sleephttp://www.bbc.com/news/magazine-16964783
The myth of the eight-hour sleep
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.
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.
Interesting information. Thanks!
Rare Gene Mutation Allows Some People to Thrive on Minimal Sleep
In the U.S., working around the clock is still glorified. According to the documentary "Sleepless in America," 40 percent of Americans are sleep-deprived. Many get less than five hours of sleep per night.
The cost is rarely considered, even though it includes reduced productivity and an increased risk of serious accidents.
Tired drivers are as dangerous as drunk or drugged ones, and experts believe sleep deprivation may have played a role in the Exxon Valdez oil spill, the Staten Island ferry crash and the Three-Mile Island nuclear meltdown, just to name a few.
Besides raising your risk of accidents that may harm or kill you or others, research clearly shows that skimping on sleep will decimate your health in a number of different ways.
Even the Centers for Disease Control and Prevention (CDC) has stated that lack of sleep is a public health epidemic, noting that insufficient sleep has been linked to a wide variety of health problems.
Genetic Mutation Makes Some People More Efficient Sleepers
Interestingly, there are a few rare individuals who can get by on very little sleep without incurring any noticeable harm. There's an actual condition called advanced phase sleep syndrome — a genetic mutation that allows you to be fully rested after as little as four to six hours of sleep.1
In the TED Talk above, Ying-Hui Fu, Ph.D.,2 a professor at the University of California San Francisco (UCSF) School of Medicine who studies the genetic basis for humans who have shorter sleep duration discusses some of her findings.
She and her colleagues have identified several genetic mutations that produce "extreme morning lark phenotype," as well as mutations that allow short sleepers to thrive.
A 2009 study investigating a mother and daughter with this rare gift found a genetic mutation on a specific gene transcription facilitator may be responsible. The gene DEC2 is involved in the regulation of your circadian clock, which is part of the equation.
DEC2 also appears to induce more efficient sleep with more intense REM states, and researchers believe this is the primary reason why people with advanced phase sleep syndrome can thrive on so little sleep and suffer no ill health effects. According to Fu:3
"Clearly people with the DEC2 mutation can do the same cleaning up process in a shorter period of time — they are just more efficient than the rest of us at sleeping."
Chances Are, You Need More Sleep Than You're Getting
People with genetic mutations that allow them to be extreme short sleepers are also typically very optimistic and naturally energetic,4 Fu notes. Many work two jobs at a time, not because they must but because they're highly motivated. And, since their sleep requirement is so low, they can.
However, the chances of you having this genetic mutation are very slim. It's been estimated that far less than 1 percent of short sleepers (people who claim to function well on less than the normal seven or eight hours of sleep) have the mutation — the remaining 99 percent are actually sleep-deprived.
Another estimate is that 1 in 10,000 may be genetically predisposed to short sleep. For everyone else, you really need right around eight hours of sleep every night for optimal health and wellness.
According to Fu, if you deprive yourself of just two hours of sleep per night for one week, your mental alertness will be the same as if you stayed up for 48 hours straight.
Sleep restriction can also lower your motivation and enjoyment, so skimping on sleep to get ahead professionally or to have more time to do things you like is actually counterproductive.
Habitual Short Sleepers May Be More Tired Than They Realize
In another study,5,6 researchers at the University of Utah used MRI scans to look at the neurological wiring of habitual short sleepers, revealing those who did not report daytime dysfunction had enhanced connectivity between the hippocampus and the sensory cortices.
These areas are involved in memory and sensory input processing respectively. In other words, it appears short sleepers may be able to more effectively perform memory consolidation tasks during the daytime, thereby reducing their brain's need for sleep.
That said, the researchers also found that many may actually be underestimating their need for sleep. The researchers first compared data from individuals who reported normal sleeping patterns with those who reported sleeping six hours or less.
The short sleepers were then subdivided into two groups: those who reported daytime dysfunction and those who claimed to function optimally.
Both groups had brain connectivity patterns that were more typical of sleep while in the scanner, opposed to patterns suggesting wakefulness, suggesting the short-sleepers were nodding off even though they'd been told to stay awake during the procedure.
On the one hand, this meant they were more likely to be engaged in memory consolidation tasks, which can occur even during quick nod-offs. On the other hand, it may also suggest they're not quite as rested and functional as they imagine. As reported by R&D Magazine:7
"For short-sleepers who deny dysfunction, one theory is that their wake-up brain systems are constantly in overdrive. Which could mean that when they are trapped in boring fMRI scanners, they have nothing to do to keep them awake and therefore doze off.
'It looked like the short-sleepers showed brain connectivity changes that look like they were preferentially falling asleep.
This was not only the case for short sleepers who reported being tired during the day, but also for the ones who said they felt fine,' [Dr. Jeff] Anderson added … [T]hey may be falling asleep during the day under low-stimulation conditions, often without realizing it."
3 Types of Short Sleepers
On the whole, researchers appear to agree that a vast majority of short sleepers are fooling themselves and really are not wired to get by on four to five hours of sleep. They're also in agreement that you cannot train yourself to require less sleep.8,9
Likewise, natural short sleepers cannot force themselves to sleep longer, and will report feeling worse for wear if they do. As noted by Ethan Green, founder of No Sleepless Nights, there are three general types of short sleepers:10
Those who have a sleep disorder, such as insomnia, which prevents them from sleeping as much as they'd like
Those who falsely believe they don't need much sleep and, for work, study or social reasons, chose not to sleep for more than six hours per night
True short sleepers, who due to their genetic makeup can thrive and function well on very little sleep
How can you tell if you're a natural short sleeper? Green offers the following common-sense suggestions:11
Take a vacation of at least two weeks; ideally avoiding jet lag
If needed, take a couple of days to catch-up on lost sleep
Each night, go to bed at your normal time — preferably as soon as you feel tired, and do not set your alarm clock
Over the course of several days of going to bed and rising without an alarm clock, you will know how much sleep your body needs
Is It Possible to Become a More Efficient Sleeper?
While researchers such as Fu suggest we may one day be able to figure out a way to enable people to sleep less by tapping into our genetic code, until then, we're stuck with our natural sleep needs. You can, however take steps to become as efficient a sleeper as possible. The most effective way of optimizing your sleep needs is to set and keep a consistent wakeup time. As reported by BBC News:12
"Neil Stanley, [Ph.D.,] an independent sleep consultant … says that when your body gets used to the time it needs to wake up, it can use the time it has to sleep as efficiently as possible. 'Studies show that your body prepares to wake up one and a half hours prior to actually waking up. Your body craves regularity, so if you chop and change your sleep pattern, your body hasn't got a clue when it should prepare to wake up or not' …
Stanley says that a lot of people with sleep issues actually don't have any problem sleeping, instead they have an expectation that they need to sleep for a certain amount of time. 'If we could all figure out what kind of sleeper we are, and live our life accordingly, that would make a huge difference to our quality of life,' he says."
Those over 60 dont need a lot of sleep.
We arent growing - unless you mean - growing old.
4 hours are enuf. We nap.