A lack of sleep can double the risk of death from cardiovascular disease, but too much sleep can also double the risk of death, British researchers found.

Researchers from the University of Warwick, and University College London have found those who had cut their sleeping from 7 hours to 5 hours a night or less faced a 1.7 fold increased risk in mortality from all causes, and twice the increased risk of death from a cardiovascular problem in particular.

They also found that those, who increased their sleep from 8 hours or more a night, were more than twice as likely to die predominantly from non-cardiovascular diseases.

Francesco Cappuccio of the University of Warwick’s Warwick Medical School studied how sleep patterns affected the mortality of 10,308 civil servants in the Whitehall II study at two points in their life during 1985 to 1988 and those still alive in 1992 to 1993.

The researchers took into account other factors such as age, sex, marital status, employment grade, smoking status, physical activity, alcohol consumption, self-rated health, body mass index, blood pressure, cholesterol and other physical illness.

The findings were presented to the British Sleep Society.