In fact, an extra hour of sleep each night was associated with a 33% lower chance of coronary artery calcification, a reduction in heart risk that’s on par with having about a 16-point drop in systolic blood pressure, according to a study published in Wednesday’s issue of the Journal of the American Medical Association.
“There really is mounting evidence that there likely are subtle health consequences of really short nighttime sleep,” says Diane S. Lauderdale, PhD, of the University of Chicago, one of the authors of the study.
The study is the first to show this relationship and it can’t prove that short sleep actually causes artery clogging, so it must be confirmed by other research, Lauderdale cautions. And it’s not clear if trying to get more sleep can reduce coronary artery calcification. Nevertheless, she adds, “it’s probably a good idea to sleep at least six hours a night.”
In the study, called Coronary Artery Risk Development in Young Adults (CARDIA), the researchers looked at 495 men and women who were 35 to 47 years old and free of coronary artery calcification in 2000 or 2001. Five years later, 12.3% had signs of calcium accumulation in their heart arteries.
The volunteers wore a wristwatch-like device to track their movement overnight, a technique called actigraphy that’s a much more accurate way to measure sleep time than personal estimates. CT scans were used to measure calcium deposits in the coronary arteries. The volunteers got an average of five to seven hours of sleep a night.
The calcification risk declined steadily as the number of sleep hours increased, even after the researchers accounted for participants’ age, sex, race, level of education, whether or not they smoked, and whether or not they had sleep apnea, a sleep disorder that interrupts breathing and raises blood pressure and heart risk.