Sleeping less than six hours a night increases the risk of early death, it was claimed today.
Scientists arrived at the result after analysing data from 16 studies involving more than 1.5 million participants. They found "unequivocal evidence" of a direct link between sleeping less than six hours a night and dying prematurely. People who regularly had this little sleep were 12% more likely to die over a period of 25 years or less than those who got the recommended six to eight hours.
An association was also seen between sleeping more than nine hours a night and early death. This was thought to be due to long-sleeping being a marker of serious underlying illness rather than any effect of sleep itself.
Professor Francesco Cappucio, head of the Sleep, Health and Society Programme at the University of Warwick, said: "Whilst short sleep may represent a cause of ill-health, long sleep is believed to represent more an indicator of ill-health."