Restful sleep: sleeping 4 or 6 hours is useful due to gene mutation

Some people can feel fully rested after sleeping only four to six hours a night, and genes could be behind this condition. A scientific team from the United States and China has discovered a new human genetic variant associated with naturally short sleep, according to EFE.

Their description is published in the journal "Proceedings of the National Academy of Sciences" (PNAS), and, according to the scientists, this discovery serves to advance our understanding of sleep regulation and, in the future, offer possible therapeutic options to improve it.

Behind the new work are researchers from the University of California, San Francisco, and the Chinese Academy of Sciences.

Until now, the scientific community linked four genes to this type of short sleep. In this new study, using whole-exome sequencing—the part of the genome that codes for proteins—the team identified another mutation, this time within the SIK3 gene.

Once identified, researchers led by Ying-Hui Fu and Guangsen Shi found in laboratory experiments that a mutation (N783Y) altered the structure of the SIK3 protein, hindering its ability to transfer phosphate molecules to other proteins, a process known for its involvement in sleep regulation.

To confirm their findings, the authors generated mice carrying the aforementioned mutation and found that the mutant rodents slept on average 30 minutes less each night, compared to unaltered animals.

Computer modeling later indicated that the mutation causes structural changes that affect the protein's ability to transfer phosphate groups.

The protein abundance was similar between the mutant and unaltered mice, indicating that the changes in protein phosphorylation—the process by which a phosphate group is added to a molecule—were due to altered SIK3 activity and not altered protein levels, the journal summarizes.

The results suggest that SIK3 may play a key role in human sleep duration. “These findings expand our understanding of the genetic basis of sleep,” the authors write in their article.

They also highlight the broader implications of kinase activity—enzymes—in sleep regulation across different species and “provide further support for potential therapeutic strategies to improve sleep efficiency,” the scientists add.