It’s the Goldilocks principle: not too much, not too little.
Not getting enough sleep can lead to health problems — that’s been studied time and time again. But a new University of Colorado Boulder seven-year study of almost half a million people found that getting too much sleep can boost your risk of a heart attack.
The research, which was published Monday in the Journal of the American College of Cardiology , found that the healthiest amount of time a person should sleep is between six and nine hours.
For the study, senior author Celine Vetter, who’s an assistant professor of integrative physiology at CU Boulder, and her co-authors at the Massachusetts General Hospital and the University of Manchester analyzed genetic information, self-reported sleep habits and medical records of 461,000 UK Biobank participants between the ages of 40 and 69 who had never had a heart attack. The study followed the participants for seven years.
Participants who slept less than six hours were 20 percent more likely to have a heart attack during the study period, according to the researchers. Those who slept more than nine hours were 34 percent more likely. The more people fell out of the 6-to-9-hours timeframe, the more at-risk they were for a heart attack.
When the researchers looked at participants with a genetic predisposition to heart disease, they found that those who slept between six and nine hours cut their risk of having a heart attack by 18 percent.
“This provides some of the strongest proof yet that sleep duration is a key factor when it comes to heart health, and this holds true for everyone,” Vetter said.
Research has long indicated some sort of association between sleep and heart health, but with countless other factors, researchers haven’t been able to pinpoint if poor sleep causes heart problems or vice versa. In this new study, researchers combined observational and genetic research to ask questions in a new way and incorporate 30 other factors — including body composition and physical activity — into account.
After doing this, they found that sleep duration influenced heart attack risk independently of the other factors.
Lead author Iyas Daghlas, a medical student at Harvard University, said he hopes this can be a hopeful message for the public.
“Regardless of what your inherited risk for heart attack is, sleeping a healthy amount may cut that risk just like eating a healthy diet, not smoking, and other lifestyle approaches can,” he said.