[unable to retrieve full-text content] What to know about melatonin supplements and heart health risks CNN Popular Sleep Supplement Could Be Harming Your Heart, Doctors Warn SciTechDaily Long-term use of melatonin supplements linked to higher risk of heart failure and death News-Medical Does Melatonin Lead to Heart Failure? New Study Findings, Explained TODAY.com Melatonin Has Been Linked to Heart Failure. Here's What Sleep Experts Say to Do Now SELF Magazine Study suggests long-term melatonin use may impact heart health NewsNation