The connection between skipping sleep and heart problems is much stronger than thought, according to a report published in the “Journal of the American Medical Association.”

Previous research had suggested a weak link between sleep deprivation and the risk of getting heart disease. But University of Chicago researchers decided to carry out a new study since the earlier ones were based on participants’ self-reports of their sleep times, which are usually unreliable - because people tend to overstate the amount of sleep they get.

A team of scientists conducted by Diana Lauderdale, an epidemiologist at the University of Chicago, followed almost 500 middle-aged adults from the United States, who were equipped with an $850 device called an actigraph. In order to determine volunteers’ underlying heart health, researchers did computerized tomography (CT), scans of their coronary arteries. Participants slept about six hours a night; only few of them got more than eight hours of nightly sleep.

After five years of follow-up, researchers found that the risk of participants who got five to seven hours of sleep a night to develop early signs of blood-vessel damage was almost 50 percent higher, compared to those who get more rest. And people who regularly sleep less than five hours nightly were at even higher risk.

“There’s mounting evidence that really short sleep duration, as in less than five hours a night, may well have health consequences,” lead researcher Lauderdale said in a telephone interview. “It’s pretty safe to say that it’s a good idea to get more than five hours of sleep a night.”