Long-Term Melatonin Use Linked to Increased Heart Failure Risk

Study Finds Higher Heart Failure Risk With Long-Term Melatonin Use

A preliminary study presented at the American Heart Association's Scientific Sessions 2025 found that adults with chronic insomnia who used melatonin for at least a year had about a 90% higher risk of developing heart failure over the following five years compared to similar adults who did not use melatonin.

The research used data from the TriNetX Global Research Network, analyzing electronic health records from a large international group of adults with chronic insomnia. People with prior heart failure or who used other sleep medications were excluded.

What the Evidence Shows: Study Design and Findings

The study compared two groups: adults with chronic insomnia who had at least one year of documented melatonin use, and a matched group with insomnia but no melatonin use. Over five years, heart failure occurred in 4.6% of the melatonin group and 2.7% of the non-melatonin group.

A secondary analysis, which included only people who filled at least two melatonin prescriptions at least 90 days apart, found an 82% higher risk of heart failure. The study also found higher rates of hospitalization for heart failure and death from any cause in the melatonin group.

Implications for Sleep, Recovery, and Metabolic Health

Melatonin is widely used as an over-the-counter sleep aid, especially for insomnia and jet lag. Many people view it as a 'natural' or harmless supplement, but evidence about its long-term safety, especially for heart health, has been limited.

People managing metabolic health often focus on sleep quality and recovery. This study suggests that long-term melatonin use may carry risks for heart health, particularly for those with chronic insomnia, and highlights the need for careful consideration and discussion with a healthcare provider.

Limitations and What Remains Unclear

The study does not prove that melatonin causes heart failure. It shows an association, not a direct cause-and-effect relationship. Other factors may contribute to the increased risk.

Melatonin supplements in the United States are not regulated for strength or purity, which could affect results. The findings are preliminary and have not yet been peer-reviewed or published in a scientific journal.

What to Consider Before Using Melatonin Long Term

Anyone considering long-term melatonin use for sleep or recovery should be aware of these new findings and discuss them with a healthcare professional, especially if they have chronic insomnia or other risk factors for heart disease.

Further research is needed to confirm these results and to understand the underlying reasons for the observed association between melatonin use and heart failure risk.