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Wednesday, June 17, 2009

Getting 1 hour EXTRA sleep can save from heart attacks!

“We found that people who on average slept longer were at reduced risk of developing new coronary artery calcifications over five years,” said Diane Lauderdale of the University of Chicago Medical Center, whose study appears in the Journal of the American Medical Association. “It was surprisingly strong.” Calcium deposits in the coronary arteries are considered a precursor of future heart disease. Unlike other studies looking at the risks of getting too little sleep, which use people’s own estimates of their sleep patterns, Lauderdale’s team set out to measure actual sleep patterns.

They fitted 495 people aged 35 to 47 with sophisticated wrist bands that tracked subtle body movements. Information from these recorders was fed into a computer program that was able to detect actual sleep patterns. The team used special computed tomography scans (i.e. CT scans) to assess the buildup of calcium inside heart arteries, performing one scan at the start of the study and one five years later. After accounting for other differences such as age, gender, race, education, smoking and risk for sleep apnea, the team found sleep duration appeared to play a significant role in the development of coronary artery calcification. About 12% of the people in the study developed artery calcification during the five-year study period. Among those who had slept less than five hours a night, 27% had developed artery calcification. That dropped to 11% among those who slept five to seven hours, and to 6% among those who slept more than seven hours a night.

Lauderdale said it is not clear why this difference occurred in people who slept less, but they had some theories. Because blood pressure tends to fall off during sleep, it could be that people who slept longer had lower blood pressure over a 24-hour period. Or, it could be related to reduced exposure to the stress hormone cortisol, which is decreased during sleep.

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