Too little sleep can lead to coronary heart disease, says a recent study by Brigham and Women's Hospital in Boston. Women who averaged five hours or less of sleep a night were 39 percent more likely to develop coronary heart disease--the number one killer among African-Americans--than women who got eight hours of sleep. Those who slept six hours had an 18-percent higher risk of developing coronary heart disease, which, according to the American Heart Association, kills more than 50,000 Blacks each year.