Why some flourish on few hours of sleep? It's sleepiness gene!

Scientists claim to have found a "sleepiness" gene that affects whether people rise refreshed and ready to attack the day -- or would rather turn over and go back to sleep, the 'Daily Mail' reported.

According to them, people with the "sleepiness" gene feel more tired than others, even after getting a good 10 hours of shut-eye two nights in a row; they also take lack of sleep harder than others.

For the study, the scientists focused on 37 volunteers who had a genetic flaw linked to narcolepsy, a sleep disorder in which sufferers fall asleep without warning. Despite having the gene, the men and women did not suffer from nacrolepsy and were classed as healthy sleepers.

For the first two nights of the study, they were allowed to sleep for up to 10 hours. For the next five, they were only allowed four hours in bed. Another 92 adults without the genetic flaw followed the same routine.

Those with the flawed gene were sleepier and more fatigued no matter how much or how little sleep they had. They also woke up more during the night and spent less time in restorative deep sleep, the findings revealed. "This gene may be a biomarker (biological signal) for predicting how people will respond to sleep deprivation, which has significant health consequences and affects millions of people around the world.

"It may be particularly important to those who work on the night shift, travel frequently through multiple time zones or just lose sleep due to their multiple work and family obligations.

"However more research and replication of our findings are needed," lead scientist Namni Goel of the University of Pennsylvania was quoted as saying.

The findings have been published in the latest edition of the 'Neurology' journal.