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How Many Hours Sleep Do You Really Need?

The general rule of thumb for what counts as a full night’s sleep has been eight hours for as long as anyone can remember, but it’s not an arbitrary number at all. Two studies, one at the University of Pennsylvania and the other at the Walter Reed Research Institute, tested dozens of sleepers and found that sleeping even seven hours a night will slowly add up to a costly sleep debt.

Photo remixed from an original by Tom Small.

The studies lasted about four years and posted their results in 2003, but most people still operate under the old assumption that five or six hours of nightly sleep is enough to operate indefinitely, without any consequences. While it’s true that a small percentage of people can actually pull it off, the number for most of us is a rock-solid eight hours — anything less and we begin to suffer major losses in everything from attention span to reaction time.

The participants in the study were tested in a controlled laboratory setting for a period of two weeks. Those who slept eight or nine hours didn’t show any signs of slowing down when tested, but the four and six hour groups were found to be impaired to the point of being “the cognitive equivalent of being legally drunk” at the end of the two-week period. Sleeping in on the weekends won’t necessarily make it better, either. We just need to sleep more.

If you’re having trouble meeting your eight hour quota, here are some tips for sleeping better. Read more about the studies and their results by hitting the link below.

How Little Sleep Can You Get Away With? [New York Times]


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