Demanding A Recount Of Those Sheep
The Economist has a bunch of articles on new technology, including one on sleep. I'd never heard of "core sleep" before:
A new, contrarian school of thought is emerging. The eight-hours mantra has no more scientific basis than the tooth fairy, says Neil Stanley, head of sleep research at the Human Psychopharmacology Research Unit at the University of Surrey in Britain. He believes that everyone has their own individual “sleep need” which can be anywhere between three and 11 hours. “If you’re a three-hour-a-night person, you need three; if you're 11, you need 11.” To find out, he says, simply sleep until you wake naturally, without the aid of an alarm clock. Feel rested? That’s your sleep need.Core sleep beats deep sleep
The global get-to-sleep industry—pills, lotions, “no-turn” mattresses, foam “memory” pillows and the like—has conditioned us to think we’re not getting enough, adds Jim Horne, director of the sleep research centre at Loughborough University in Britain and author of the new book, “Sleep Faring: A Journey through the Science of Sleep”. What really matters, he says, is the “core” sleep, the first few hours that nourish the higher sections of the brain. Anything beyond that—including deep REM (rapid eye movement) sleep—is “non-essential” and taken for pure pleasure. Consider the domestic cat: feed it well, and it sleeps a lot; withdraw the food, and it’s out hunting.As long as you’re not a zombie the next day, you’re probably sleeping enough, says Dr Stanley. He appeals to the concept of “non-restorative sleep” recently put about by the German Society of Sleep Research and Sleep Medicine. In Germany, there has been a shift in emphasis: traditionally, treatment focused on reducing sleep “latency”—the interval between settling in for the night and the onset of sleep—and thus prolonging total sleep time. Now, the focus is on restoring the recuperative value of sleep and ensuring daytime functioning on a social, psychological and professional level.
In truth, however, no one really knows whether ten hours a night is any better than five. The science of sleep has not advanced an awful lot since 1834, when the first book in the English language on the subject—“The Philosophy of Sleep” by a Glaswegian physician called Robert MacNish—was published. Of course, we can now plot brainwaves, track hormones and add new taxonomies to the International Classification of Sleep Disorders (89, at the last count).
We can link sleep problems to driving and industrial accidents; to a higher rate of divorce; to increased risks of heart disease, breast cancer, diabetes, colo-rectal cancer and obesity. We’re also confident of the role of sleep in reinforcing memory, learning and cognitive performance. But the real fundamentals—such as why we sleep, and why some people can function on less than others—elude us.
More on this here (including "pure Uberman"), and here, in an article by Dr. Gregg D. Jacobs:
There is considerable evidence suggesting that for many individuals, performance on alertness, memory and problem-solving tasks can be maintained for extended periods of time with about 5.5 hours of sleep, or what is called “core sleep”:..Findings on the effects of sleep loss suggest that it is important to differentiate between moderate sleep loss (5 to 6 hours of sleep) and severe sleep loss (4 or less hours of sleep). The latter produces more significant effects on daytime performance.
Core sleep (5.5 hours of sleep) probably maintains performance because it contains 100% of our deep sleep, which is the most important stage of sleep and 50% of REM sleep, which is the second most important stage of sleep. Core sleep does not have to be obtained continuously. In fact, research on soldiers, fire fighters, rescue workers and astronauts suggest that by breaking up sleep into multiple periods throughout the day (for example, 6 30-minute naps taken every 4 hours), sleep can be reduced below core sleep — to as little as 3 hours per day — without significant consequences.
Another important finding about core sleep is that, if it is not obtained one night, the brain will create increased pressure to obtain core sleep the next night. How do we know this? On nights after core sleep loss, the brain compensates by producing an increased percentage of deep sleep and dream sleep, which explains why we don't have to recover all of the sleep we lose. (The fact that we don't need to recover all the sleep we lose argues against the accumulation of a sleep debt). This finding, coupled with the fact that insomniacs average 5.75 hours of sleep, suggests that the brain seems to be programmed to obtain core sleep.
There are a lot of zombies out there who think they don't need 8 hours a night.
Lena at May 30, 2006 4:49 PM
The first famous sleep researcher, Sigmund Freud, had to recant his ideas and observations because they were too controversial. Are you getting ideas ?
opit at May 31, 2006 2:40 PM
Rats. Showing a Server 500 ( that's new to me ) Error. Sorry about the double.
opit at May 31, 2006 2:43 PM
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