Scientists have found out why some people get enough sleep in four hours

Scientists from the Weill Institute for Neurosciences at the University of California have found that a rare genetic variant of ADRB1 can increase the activity of neurons responsible for wakefulness. This allows a person to sleep four to six hours each night without obvious signs of sleep deprivation. The results of the study were published in the journal Neuron.

Researchers studied a rare mutation in the ADRB1 gene, previously discovered in a family where several generations exhibited unusually short sleep duration. Carriers of the variant could go their entire lives getting by on approximately six hours of sleep or less while still feeling fine.

Experiments on genetically modified mice showed that the mutation alters the functioning of the ADRB1 receptor. It is prominently expressed in a region of the brainstem associated with the regulation of wakefulness. In mutation carriers, the corresponding nerve cells are more easily activated and remain more active during the waking period. As a result, the brain switches more quickly from a state of sleep to wakefulness, reducing overall sleep duration.

The scientists also tested how widespread this effect is beyond the original family. To do this, they analyzed data from 191,929 individuals with genetic and sleep information. The ADRB1 mutation was found in 69 unrelated participants. However, they slept an average of 7.1 hours compared to 7.2 hours for carriers of the usual gene variant, meaning they were practically no different from them.

The researchers believe that the same mutation can manifest differently depending on a person's other genetic characteristics. Therefore, the presence of the ADRB1 variant alone does not necessarily mean that a person truly requires less sleep.

ADRB1 is not the only gene associated with naturally short sleep. Scientists have previously discovered variants in DEC2, NPSR1, GRM1, and SIK3. This points to the existence of an entire group of genetic mechanisms capable of influencing sleep duration.

"At the same time, the study does not mean that an ordinary person can safely reduce sleep to four to six hours. This is about a rare hereditary trait, not an ability that can be acquired through training. For most people, sleep deprivation remains associated with health risks," the scientists warned.