Folks using melatonin supplements as a sleep aid might be putting themselves at risk for future heart problems, a new study says. Adults with insomnia who'd been using melatonin for a year or more had 90% higher odds of heart failure, researchers are scheduled to report Nov. 10 in New Orleans at a meeting of the American Heart Association. Further, people taking melatonin are nearly 3.5 times more likely to be hospitalized for heart failure, researchers found. "Melatonin supplements are widely