Researchers at the University of California San Francisco havediscovered a gene that might explain why some people need less sleepthan others. Experts say the findingopens the door into the study of sleep.
Sleep is an essential process. Laboratory animals that are deprived of it for prolonged periods of time eventually die.
Nonetheless, Ying-Hui Fu with the University of California San Francisco says little is known about this basic human need.
"Wedo not know how our sleep is regulated," she said. "We do not know whysome people need more sleep; why some people need less sleep; why mostof us need eight hours of sleep; why, when we do not sleep, we do notfunction very well. We just do not know much about sleep at all."
Fusays sleep can be induced in humans when they drink alcoholic beveragesor take sleeping pills. But she says no specific gene had beendiscovered that appeared to be involved in regulating sleep - until now.
Fu'sresearch team stumbled across the sleep gene while looking for amolecular mechanism underlying circadian rhythms - a natural internalclock that regulates the shift between sleep and wakefulness during a24-hour period.
In the course of their studies, Fu saysresearchers identified a genetic mutation in people who go to bed at anormal time but sleep only for about six hours, feeling as refreshedwhen they wake up as those who appear to need eight hours or more ofsleep.
"We have these human subjects that carry this mutation and they look fine," she said.
Investigatorsgenetically engineered mice to carry the mutation, and compared theirsleep cycles and brain activity to rodents that did not have thegenetic abnormality. They found that those with the gene slept lessand were awake for longer periods of time. Mice with the mutation alsowere more energetic than normal mice, after being deprived of sleep.
Although the gene mutation is thought to be extremely rare, Fu says it is a significant find for sleep researchers.
"Weessentially do not know anything about how sleep is regulated," shesaid. "But this gene is kind of opening a door for us to say, 'Now wehave this gene and we know it affects human sleep quantity.'"
Fu adds that the gene might be related to other medical conditions.
"Itis too early for me to make any conclusion because now that we havethis mouse model, we can use a mouse to test whether mice that carrythis mutation have metabolic problem[s] or they have psychiatricproblem[s] or they have psychological problem[s]. We can start goinginto this field," she said.
Fu and her colleagues will alsoexamine whether the gene controls the amount of sleep a person needs aswell as the drive to fall asleep.
It is thought that sleep isalso controlled by homeostasis, an internal process that keeps track ofhow much sleep people need and makes them feel tired so they will go tobed.
The study on the sleep gene is published this week in the journal .