According to The Lancet: According to a prospective study (enrolling more than 500,000 people and following them for more than seven years), working more than 55 hours a week increased the risk of stroke by 33 percent and coronary heart disease by about 13 percent. Scientists point out that, of course, you should also maintain normal blood pressure, blood lipids and blood sugar, moderate physical activity, a healthy diet and weight, adequate sleep, and avoid excessive stress.