Getting a good night’s sleep plays a significant role in protecting you from heart attacks, according to a study involving 500,000 people. For the first time, it provides strong evidence that too little sleep (less than six hours) over a period of years causes your risk of heart attack to rise substantially. On the flipside, if you are genetically predisposed to heart attack, good sleep hygiene can reduce that risk. Sleeping between seven to nine hours a night is doctors’ recommendation. The findings come from a collaboration between the University of Colorado Boulder, Harvard Medical School and the University of Manchester.