NYT
Getting less than six hours of sleep a night, or more than nine hours, might increase the risk for heart attack.
.... For the current study, researchers had DNA data about study participants and knew who had a high or low genetic risk for cardiovascular disease. This allowed them to more clearly identify the role of sleep duration by itself on heart attack risk and provided greater certainty that the relationship might be causal.
The study, in the Journal of the American College of Cardiology, included 461,347 men and women ages 40 to 69, all of whom were healthy at the start. Over seven years of follow-up, there were 5,218 heart attacks.
Comparing people with the same low genetic risk score for cardiovascular disease, they found that those with poor sleep duration — less than six hours or more than nine — had a 32 percent higher risk of having a heart attack.
