The problem with new medical studies it just makes things more complicated! Too little sleep is bad, but too much sleep can be bad! What's a person to do? People who sleep less than seven hours, or even more, greatly increase their risk of cardiovascular disease, which is the leading cause of death in the U.S. That's the word from medical researchers at West Virginia University in Morgantown, who determined that the people who are most at risk are those who sleep less than five hours a day. This more than doubles their chance of developing angina, coronary heart disease, heart attack or stroke. Too much sleep can be just as dangerous. Those who sleep nine hours or more a day, run a risk of having a heart attack or stroke that is one-and-a-half times higher than those who sleep less.