About two-thirds of Americans are getting too little or too much sleep , risking their health, a new study suggests. In fact, people not getting the right amount of sleep -- seven to nine hours a night -- had a 29% increased risk of premature death from any cause, researchers reported Thursday in JAMA Network Open . Advertisement "These findings provide new evidence that irregular sleep patterns over a five-year period may increase the risk of all-cause and cardiovascular disease mortality,"