British and Italian researchers have said that people who sleep for less than 6 hours each night have an increased risk of dying prematurely.

Those who slept for less than 6 hours a night were 12 percent more likely to die prematurely than those who slept the recommended 6-8 hours a night, researchers at the University of Warwick and the Federico II University Medical School in Naples, Italy, have found.

Published in the journal Sleep, the study also said sleeping more than 9 hours a night is not linked to premature death, but can indicate a serious or potentially fatal illness.

It was also reported that the researchers reviewed 16 studies from Britain, the United States, Europe and East Asia that involved more than 1.3. million people with up to 25 years of follow-up.

Francesco Cappuccio of the University of Warwick and physician at the University Hospitals Coventry and Warwickshire NHS Trust said in a statement, "Modern society has seen a gradual reduction in the average amount of sleep people take, and this pattern is more common amongst full-time workers, suggesting that it may be due to societal pressures for longer working hours and more shift-work. Consistently sleeping 6 to 8 hours per night may be optimal for health." (With Inputs from Agencies)