Why do some people feel refreshed after sleeping six hours, while others are groggy unless they get at least eight? It's genetic, and as ScienceNow reports, researchers at Stanford University in California have found a gene linked to the disparity.
ScienceNow says Ying-Hui Fu and her colleagues were initially studying a delayed sleep disorder, which causes people to sleep and rise extremely early. As part of their research, they collected DNA samples from 60 families and have been "mining" it for sleep-related mutations. The data have now allowed Fu to find "the first genetic mutation in humans that appears to affect sleep duration rather than sleep timing." ScienceNow has more:
The mutation lies in DEC2, a gene that codes for a protein that helps turn off expression of other genes, including some that control circadian rhythm, the internal clock that regulates a person's sleep-wake cycle. The mutation occurred in just two people, a mother and her daughter. The women sleep an average of only 6.25 hours, whereas the rest of the family members sleep a more typical 8 hours.
To confirm that this mutation shortens sleep, Fu and colleagues engineered mice to carry the mutant form of DEC2. The mutant mice slept about an hour less than normal mice, the team reports today in Science. The finding also held for fruit flies: Mutant flies slept about 2 hours less than normal flies.
Now, there may be other genes at play. That's according to Paul Shaw of Washington University in St. Louis, who nonetheless praised the work. Fu, meanwhile, said her discovery could help better treat sleep disorders—and she would take DEC2 if it were available in pill form. "All my life I've wanted to be able to sleep less," she confessed.