WEDNESDAY, March 30, 2005 (HealthDay News) -- A mutant gene behind an "early bird" sleep disorder has been identified by U.S. researchers.
People with this "time-shift" trait -- called familial advanced sleep phase syndrome (FASPS) -- consistently fall asleep at an early hour and then wake up well before dawn.
An estimated 0.3 percent of humans have FASPS, according to the researchers. They don't necessarily get less sleep than other people, but they do sleep on a different schedule than most of the rest of us. Some people with FASPS adjust to this time-shift, while others are bothered by being out of sync with those around them
Looking into the problem, researchers at the Howard Hughes Medical Institute and the University of California, San Francisco studied a family strongly affected by FASPS. They discovered that the mutation responsible for FASPS lies in a gene with no previous connection to circadian rhythm.
It isn't yet clear exactly how this mutant gene affects a person's sleep cycle, since it appears to act differently in different species. For example, in fruit flies the mutant gene lengthens circadian rhythm, while it shortens it in mice and humans, the researchers said.
"These results show that the gene is a central component of the mammalian circadian clock, and suggest that mammalian and fly clocks may have different regulatory mechanisms, despite the highly conserved nature of their individual components," the study authors conclude.
They believe further studies in humans, mice and fruit flies should increase our understanding of the similarities and differences of how this gene works in different settings and genetic backgrounds.
The findings appear in the March 31 issue of Nature.
More information
The U.S. National Institute of Mental Health has more about biological clocks.
