Taking Melatonin Every Night May Nearly Double Heart Failure Risk

A recent study of adults with chronic insomnia found a link between long-term melatonin supplement use and an increased risk of heart failure and early death. Melatonin is widely used in the United States, with about six million people taking it to fall asleep faster or stay asleep longer.

Researchers observed that adults with insomnia who took melatonin for at least one year were significantly more likely to develop or be hospitalized for heart failure or die from any cause over a five-year period, compared to those who did not use the supplement.

“Melatonin supplements may not be as harmless as commonly assumed,” says lead study author Ekenedilichukwu Nnadi, MD, chief resident in internal medicine at Kings County Hospital and Downstate Health Sciences University in Brooklyn, New York.

Dr. Nnadi adds that if further studies confirm these results, it could influence how doctors weigh the risks and benefits of melatonin when discussing sleep aids with their patients.

Study Methodology

The researchers analyzed health records from a large international database including over 130,000 adults with insomnia and no prior heart failure diagnosis. They compared individuals who used melatonin long-term (more than one year) with a matched group who had never used the supplement.

This comparison allowed the team to isolate the potential impact of long-term melatonin use on heart health outcomes.

Key Facts

Melatonin is one of the most popular over-the-counter sleep supplements in the U.S.
Long-term use was defined as taking melatonin for more than one year.
Users showed higher risk of heart failure hospitalization and mortality over five years.

Author’s summary: Long-term melatonin use in adults with insomnia may pose serious heart health risks, challenging the common perception of its safety.

Everyday Health — 2025-11-06