Image Credit: Getty Images New research has raised concerns about the long-term use of melatonin supplements, which are widely available for purchase in the United States. With countless Americans having taken the supplement at least once in their lives, many are wondering if they are at risk of heart failure. So, could taking melatonin actually lead to heart failure? Below, we break down the new study about melatonin and the risk, according to the data released by the American Heart Association as part of its Scientific Sessions.