March 27, 2012 (Chicago) -- Sleeping less than six hours a night may make you more likely to have a heart attack, stroke, or heart failure.
A new study puts numbers on that risk. The study, based on more than 3,000 people older than 45, shows that people who sleep less than six hours per night are about twice as likely to have a stroke or heart attack as people who get six to eight hours of sleep. And they are about 70% more likely to have congestive heart failure.
"The optimal sleep time appears to be six to eight hours,” says Rohit R. Arora, MD, chairman of cardiology at Chicago Medical School.
The new study, presented in Chicago at the American College of Cardiology's annual meeting, isn't the first study to link sleep and heart health. But it's one of the largest surveys to do that, Arora says.
That means a lot of Americans could be at greater risk for heart trouble because of their sleep habits. Nearly 30% of U.S. adults report sleeping no more than six hours per night, according to a national health survey.
Exactly how sleep affects the heart is not clear. Arora says he doubts not sleeping enough directly causes heart disease.
But there is evidence that not sleeping enough may ramp up the "fight or flight" response to stress, releasing hormones that speed up heart rate and raise blood pressure. If that happens chronically, it could take a toll.
Or, people could have other medical conditions, such as diabetes, that prevent them from sleeping through the night, Arora says.