Too much sleep as dangerous as too little: study

Sleeping too much, just likesleeping too little,could belinked toa person's risk of an early death,a newBritish study indicates.

Researchers at the University of Warwick's Warwick Medical School studied 10,308 British civil servants in two different time periods: between 1985 and 1988, and between 1992 and 1993.

With seven hours seen as the optimal amount of sleep for the average adult,the study subjectswho cut the duration of theirsleep from seven hours to five hours a night had a 1.7-fold increased risk of death from all causes within the ensuing 11-17 years, according to the research, presented Monday to the British Sleep Society.

They also hadtwice the increased risk of death from a cardiovascular problem.

More surprisingly, scientists found thoseindividuals who increased the number of hours they slept per night from seven to eight hours or more were more than twice as likely to die within 11-17 yearsas those who kept sleeping for seven. They were more likely to die from non-cardiovascular diseases.

"Short sleep has been shown to be a risk factor for weight gain, hypertension and Type 2 diabetes sometimes leadingto mortality," said Francesco Cappuccio, an author of the study.

"But in contrast to the short sleep-mortality association, it appears that no potential mechanisms by which long sleep could be associated with increased mortality have yet been investigated. Some candidate causes for this include depression, low socioeconomic status and cancer-related fatigue."

Cappuccio said adults should aim for seven hours of shuteye a night.

"In terms of prevention, our findings indicate that consistently sleeping aroundseven hours per night is optimal for health and a sustained reduction may predispose to ill-health."