- NEW YORK (Reuters Health)
- Many nights of little sleep--fewer than six hours a night--can impair
mental performance as much as not getting a wink for two nights in a row,
new research shows.
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- The data contradict a popular notion that our bodies
can become accustomed to functioning on sustained periods of little sleep
without any consequences, said lead author Dr. Hans P.A. Van Dongen, a
research assistant professor at the University of Pennsylvania School of
Medicine in Philadelphia.
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- The 48 participants in the study were divided into four
groups that slept either four, six or eight hours a night for two weeks,
or had no sleep for three days. The groups were monitored in a laboratory
throughout the two weeks to ensure that they did not nod off or use caffeine.
They were assessed on a battery of mental and physiological tests periodically
every day and were also asked to evaluate how tired they felt.
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- People sleeping less than eight hours a night were slower
to react, less able to think clearly and perform simple memory tasks, the
researchers report in the March issue of the journal Sleep. They also performed
as poorly on certain tasks as the individuals evaluated after one or two
nights of sleeplessness.
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- However, getting some sleep made individuals feel less
tired than those who went without sleep despite test results that showed
they were just as impaired.
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- As a consequence, Van Dongen told Reuters Health, there
should be countermeasures in place for people who cannot avoid being chronically
sleep-deprived, such as military personnel, trainee doctors, shift workers
and others.
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- Van Dongen recommends that these professions limit the
number of hours people are allowed to work, give people the opportunity
to nap at "strategic times" or allow them to use caffeine or
other chemical stimulants to maintain alertness.
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- This study is important and "relevant" because
it shows what happens when the body alone must deal with its tiredness
in the absence of chemical stimulants like caffeine or other distractions,
said Dr. Meir Kryger, a professor of medicine at the University of Manitoba
in Winnipeg, Canada, and a sleep researcher.
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- Data from the National Sleep Foundation show that Americans
sleep an average seven hours a night during the week, although 31 percent
of all adults regularly get less sleep.
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- The study also found that that there were large individual
differences in how much people needed to sleep.
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- Kryger said in an interview that everybody needs a different
amount of sleep. Getting sufficient amounts of shut-eye is a "life-style
decision," he said. "It is one of the important functions of
life and you need to control it."
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- SOURCE: Sleep 2003;26:117-126.
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