Lack of sleep linked to early death

People who have less than six hours of sleep per night are at greater risk of dying prematurely, researchers said on Wednesday.

Those who slept less than that amount of time were 12 percent more likely to die, but researchers also found a link between sleep more than nine hours and premature death.

"If you sleep enough, can develop diabetes, obesity, hypertension and high cholesterol," said Francesco Cappuccio, who led the research on the subject in Britain's University of Warwick, told AFP.

The study, conducted with the University of Naples Federico II, Italy, aggregates decade-long studies around the world with over 1.3 million people and found "clear evidence of the direct relationship" between lack of sleep and premature death.

"We believe that the relationship between sleep and the disease is not due to a series of hormonal and metabolic mechanisms," said Cappuccio.

The findings were published in the journal Sleep.

Cappuccio believes that sleep duration is a public health problem and should be considered as a behavioral risk factor by physicians.

"Society pushes us to sleep less and less," Cappuccio said, adding that about 20 percent of the population in the United States and Great Britain less than five hours sleep.

Sleeping less than six hours is "more common among full-time workers, suggesting that it may be due to social pressures working longer hours and more shift work"

The study also found a link between sleep more than nine hours a night and early death, but Cappuccio said that oversleeping is more likely to be an effect of the disease, rather than a cause.

"Physicians do not ask how you sleep, but could be an indicator that something is wrong," said Cappuccio, who directs the Sleep, Health and Society Program at the University of Warwick.

The investigation showed no adverse effects for those who sleep six to eight hours per day.