PNAS: only need to sleep 5 hours a day by DEC2 mutation

Introduction: Adequate sleep is essential for physical and mental health. Most people need about 8-8.5 hours of sleep every night to feel good. However, scientists have discovered that a genetic mutation can make people sleep only about 5 hours a day. So what is the mechanism behind this?

In 2009, Dr. Ying-Hui Fu, professor of neurology at the University of California, San Francisco, discovered a mutation in gene DEC2 in a family of natural short sleeper. The mutation causes sleepers to go to bed during normal hours (between 11pm and 12pm), but wake up naturally at 5am the next morning.

Professor Fu said: "These people did not train themselves to get up early. They were born so."

On March 12th, in the latest study published in the PNAS entitled "DEC2 modulates orexin expression and regulates sleep", Professor Fu's laboratory used a mouse model to reveal how missense mutations in the DEC2 gene are responsible for short-sleepers. Just a few hours of sleep will survive and thrive.

The genetically engineered mice used in the study had the same mutations in the DEC2 gene that were observed in human sleepers. The results of the analysis showed that DEC2 can help control the level of orexin, a hormone involved in keeping awake. The sudden change in DEC2 in sleepers seems to work by partially releasing the brakes produced by orexin.

Specifically, the study found that under normal circumstances, in the evening, DEC2 may reduce people's alertness by inhibiting the "opening of orexin gene - MyoD1"; before dawn, DEC2 will "fades away" ", allows MyoD1 to stimulate the expression of orexin, awaken you, and keep you awake all day long."

"The role of DEC2 may be to ensure that orexin expresses the right amount at the right time of the day, so that the level of orexin matches the circadian rhythm." Fu explained.

However, in sleepers, the occurrence of mutations weakens DEC2's ability to inhibit MyoD1, which allows them to produce more orexin and stay awake longer.

In summary, the authors believe that DEC2 is a transcriptional repressor of orexin expression, whereas the inhibitory activity of the mutant DEC2 becomes weaker, leading to increased expression of orexin. They also said that this study is the first step in understanding the molecular mechanisms behind DEC2's regulation of sleep.