Getting too little sleep has been linked to a number of health problems, including weight gain, diabetes, and high blood pressure, and now researchers have added another consequence to the list: coronary artery(冠動脈)calcifications(石灰化、硬化). They found that just one extra hour of sleep a day appears to reduce the risk of developing calcium deposits in the arteries, a precursor(前兆、先駆者)to heart disease. About 12% of the people in the study developed artery calcification during the 5-year study period. Among those who slept less than 5 hours a night, 27% had developed artery calcification. Only 6% of those who slept more than 7 hours a night developed coronary artery calcifications.