One more hour of sleep lessens heart risk

CHICAGO, Dec. 24 (UPI) -- Not getting enough sleep may leave you more than cranky -- it may lead to hardening of the arteries, an early step to heart disease, U.S. researchers say.

The study, published in the Journal of the American Medical Association, found calcified arteries were found in 27 percent of those who slept less than five hours a night. That dropped to 11 percent for those who slept five to seven hours and 6 percent for those who slept more than seven hours a night, the study said.

Study director Diane Lauderdale of the University of Chicago Medical Center said the study involved healthy volunteers in their 40s. About 12 percent first developed coronary artery calcification -- hardening of the arteries -- over five years of follow-up.

The benefits of sleep appeared to be greater for women, but did not vary according to race, Lauderdale said.

"The consistency and the magnitude of the difference came as a surprise," Lauderdale, said in a statement. "It's also something of a mystery. We can only speculate about why those with shorter average sleep duration were more likely to develop calcification of the coronary arteries."