Risk in Sleeping more or fewer than 7 hours leads to Cardiovascular disease
Sleep at-least seven hours a Night 

A recent study conducted by  faculty of medicine at West Virginia University (WVU) and published in the journal 'Sleep' says sleeping less than 5 hours a day and more than 7 hours a day doubles the risk of diagnosed with 
            • Coronary Heart Disease
            • Angina
            • Heart attack or stroke

Naps (Short Sleep) leads to angina, while sleeping less and sleeping too much leads to Dangerous Heart Attack and Stroke.
In that Study David Dinges heads the sleep and chrobiology unit at University of Pennsylavani school of medicine, found that 142 adults whose sleep severely restricted for 5 days because of their
            • Work week
            • slower reaction times
            • more trouble focusing
            • problem solving
Study identifies that sleep-deprived study participants who allowed to sleep for 4 hours a day risk of heart disease has been increased and the greatness were seen in those who spend 10 hours a sleep a night.

The results were adjusted for
  • age, 
  • sex,
  • race, 
  • whether the person smoked or drank, 
  • whether they were fat or slim, and 
  • whether they were active or a couch potato.
And even when study participants with diabetes, high blood pressure or depression were excluded from the analysis, the strong association between too much or too little sleep and cardiovascular disease remained.

The American Academy of Sleep Medicine recommends that most adults get about seven to eight hours of sleep each night.