Too much sleep as dangerous as too little: study

Sleeping too much, just like sleeping too little, could be linked to a person's risk of an early death, a new British study indicates.
With seven hours seen as the optimal amount of sleep for the average adult, the study subjects who cut the duration of their sleep 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. They also had twice the increased risk of death from a cardiovascular problem.More surprisingly, scientists found those individuals 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 years as those who kept sleeping for seven. They were more likely to die from non-cardiovascular diseases.

read more for this study here