Some people—an estimated 1 percent of the general population—can get away with having less than eight hours of sleep a night without having to nap during the day. And by "get away," we mean they're active, they can think and process information well, appear healthy, and they seem to lead successful lives with only four to six hours of sleep! (But they admit to feeling "awful" when they sleep for more than six hours.)
It's most likely because of a genetic mutation, as found by Ying-Hui Fu, a biologist, geneticist, and sleep researcher at the University of California at San Francisco. She discovered a gene called DEC2, and it's associated with people who naturally have less than six hours of sleep without health risks. According to her research, these people somehow gained "sleep resistance," which helps keep them from the negative effects that usually come with sleep deprivation (like cardiovascular diseases, for example).
Fu saw that DEC2 relates to the CLOCK gene, which could be manipulated to affect sleep. And this CLOCK gene (long version: Circadian Locomotor Output Cycles Kaput) is a gene that controls our circadian rhythm—our internal clock that regulates sleep and other functions that relate to sleep. That said, according to Fu, DEC2 can affect the circadian rhythm and hence change how the day to night cycle operates in people.
It's still unknown how the DEC2 mutation happens, and there's still no testing available for you to know if you have the DEC2 gene. But a study conducted by Dr. Allan Pack of the University of Pennsylvania found that these genes are inherited; meaning, if your parents or grandparents are naturally short sleepers, then you could be too.
This study is important in as far as it doesn't tell us we all should be having eight hours of sleep. It recognizes that people take different amounts of time to feel rested: it can be just four hours, or go all the way to 12. (Why the spans vary is still to be known.) According to Fu, "Sleep, like many of your other traits such as height, weight, and shape, is personal." In other words, it has a lot to do with our own genetic makeup.
So to know how many hours of sleep you really need, Fu says "The best way is to listen to your body and figure out what is the best schedule and duration for yourself. For example, when you are on vacation and have no social responsibilities and no other external influences, what is your body telling you to do and how do you feel? What makes you feel the best most of the day? Although that may sound primitive, it's still the most accurate way."
Now before you think people in this 1 percent are either really cool (hello, mutant!) or lucky for having the chance to do more in a day because they spend less time in bed, remember that productivity is a choice and that the number of hours you have in a day doesn't necessarily mean they're spent well or not wasted.
If you found that you need the usual eight hours of sleep or longer, don't feel so bad about it (we know it sucks when your busy schedule deprives you of those hours). There's coffee and tea to keep you up and help you power through a long work day. And power naps. Thank goodness.
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