Rare genetic mutation lets some people thrive on just 4 hours of shut-eye

Some lucky people have rare genetic mutations that enable them to feel well-rested after just four hours of sleep, while the rest of us need around eight hours to function.

Now, researchers have identified one of these mutations, named SIK3-N783Y, in a human super-sleeper. The team then studied the mutation in genetically modified mice and found that the mice carrying this mutation also got less shut-eye, according to a new study.

The newly identified mutation is one of several that researchers have linked to shorter sleep patterns. Scientists hope that by understanding the genetics of natural short sleepers, who seem to thrive on less sleep, they can develop better treatments for sleep disorders.

"Our bodies continue to work when we go to bed," detoxifying themselves and repairing damage, study co-author Ying-Hui Fu, a neuroscientist and geneticist at the University of California, San Francisco, told Nature. "These people [natural short sleepers], all these functions our bodies are doing while we are sleeping, they can just perform at a higher level than we can."

The researchers published their findings Monday (May 5) in the journal PNAS.

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There are a variety of negative effects associated with not getting enough sleep, from feeling sluggish and being more forgetful to an increased risk of heart problems. The amount of sleep we need varies as we age, but most adults require around seven to nine hours each night to be at their best. Those with the natural short sleep trait, however, seem to function fine with less.

A natural short sleeper requires around four to six hours of sleep per night. Not only do they thrive on less sleep than the rest of the human population, but they also tend to feel worse if they sleep for longer than their normal hours, according to the study.

Previous studies have identified four genes associated with short sleep and five relevant mutations within those genes. The newly identified mutation affects a fifth gene, Sik3, which has previously been linked to sleepiness. Researchers tested the mutation by giving it to lab mice. They found that mice with the mutation slept around 31 minutes less than those without it, and 54 minutes less following a period of sleep deprivation, which the researchers induced by gently handling the mice, according to the study.

Mice normally sleep for around 12 hours per day, much longer than humans, so this new mutation-linked sleep reduction of up to 54 minutes is less than is seen in human subjects with naturally short sleep patterns. The researchers noted that this could be due to mice usually experiencing more fragmented sleep than humans, or the result of their mouse strain being inbred.

Researchers still have much to learn about the genetics of natural short sleepers and their nighttime superpower. The new findings highlight that Sik3 is a promising therapeutic target for researchers to explore as they attempt to improve sleep efficiency and satisfaction, according to the study.

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