Scientists have discovered a genetic deviation that allows a person to feel fully rested after just three hours of sleep

Typically, people need about 7–9 hours of sleep each night to feel alert and maintain productivity throughout the day. However, geneticists have identified rare mutations that cause people to require significantly less sleep. Carriers of certain genes can replenish their energy much faster — in just three hours.

Researchers have named the mutation SIK3-N783H, and a detailed study devoted to it was published in the journal Proceedings of the National Academy of Sciences. One of the researchers, neuroscientist and geneticist Ying-Hui Fu from the University of California, is confident that further study of the genetic characteristics of people who sleep three to six hours without experiencing negative consequences or suffering from sleep deprivation will make it possible to develop treatments for insomnia — for example, sleeplessness or waking up in the middle of the night — and to restore normal sleep.

More than twenty years ago, Fu and her colleagues were approached by two women — a mother and daughter — who slept less than six hours every night. The researchers analyzed their genomes, the complete set of hereditary material in the body’s cells, and discovered a rare deviation. It was identified in one of the genes responsible for circadian rhythms — the intensity of various biological processes linked to the cycle of day and night. In simpler terms, this mutation altered the women’s internal clocks, their sleep–wake cycle. This reduced their need for prolonged sleep. Recently, it was found that there are many more such people. They were invited to the scientists’ laboratory to provide DNA samples for further study.

To date, more than a hundred people are known who sleep about three hours and feel fully rested. So far, scientists are studying five mutations — sources of the deviation found in four genes. Recently, a mutation was also discovered in the SIK3 gene. Earlier, Japanese researchers had found another mutation in this same gene that caused increased drowsiness in laboratory mice.

New experiments showed that mice with the newly discovered mutation required 31 minutes less sleep than their counterparts. The study also found that the SIK3 enzyme is particularly active in synapses in the brain — that is, at the site of contact between two neurons where nerve impulses are transmitted. Scientists concluded that this allows for a significant reduction in sleep time, as well as helping to “reboot” the brain. In the future, this discovery will help researchers to study sleep regulation issues more deeply.