Getting less than six hours of sleep a night, or more than nine hours, might increase the risk for heart attack.
Previous observational studies have found an association between sleep duration and heart attack. But 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.
The researchers also compared people with high genetic risk for heart disease. Although their risks were significantly higher than those with low genetic risk, those who tended to get favorable sleep reduced their risk by 18 percent compared with those with unfavorable sleep patterns.
The effects of sleep could have a significant impact on health and mortality, because while genes cannot be changed, sleep patterns are modifiable.
“I want to tell people that if they prioritize sleep, they can actually do something for heart health,” said the senior author, Céline Vetter, an assistant professor of integrative physiology at the University of Colorado, Boulder. “That’s what comes out of this data. What we’re lacking is studies that take a group of short sleepers, extend their sleep, and show evidence that this helps heart health. We’re on the path toward this, and this study adds to the evidence that this is worthwhile doing.”
One of the study’s seven co-authors reports having received payments from drug companies.
