How safe is long-term melatonin use? A new study raises concerns about the sleep aid

An over-the-counter sleep aid may put some users at higher risk for heart failure and death.

In a preliminary study of adults with insomnia, researchers found as association between long-term melatonin use and heart failure. People who took the supplement for at least one year also were more likely to die than those who did not use melatonin. MORE: For homeless women, pregnancy presents many challenges — from access to care to complication risks

The findings, which have not yet been published in a peer-reviewed journal, could alter current approaches to sleep medicine, researchers said.

"Melatonin supplements may not be as harmless as commonly assumed," Dr. Ekenedilichukwu Nnadi, lead author of the study, said in a statement . "If our study is confirmed, this could affect