Long-term use of melatonin supplements to support sleep may have negative health effects

A five-year review of health records from over 130,000 adults with insomnia who had been taking melatonin for at least one year revealed a concerning trend. Participants showed a higher likelihood of being diagnosed with heart failure, requiring hospitalization for it, and experiencing a higher risk of death from any cause.

Key Findings

Long-term melatonin users were more prone to heart failure and mortality.
The data come from a study to be presented at the American Heart Association’s Scientific Sessions 2025 in New Orleans.
The conference is a major global platform for cardiovascular science and evidence-based clinical updates.

What Is Melatonin?

Melatonin is a hormone naturally produced by the pineal gland that regulates the body’s sleep-wake rhythm. Levels rise at night and drop during daylight hours.

Synthetic melatonin, which mimics the natural hormone, is widely used to help with insomnia and jet lag. It is available over the counter in many countries, including the United States.

“In the U.S., over-the-counter supplements do not require government approval to ensure quality and consistency, so each brand of supplement can vary in strength and purity.”

Implications

These findings raise concerns about the safety of long-term melatonin use and highlight the need for greater oversight and research into its potential cardiovascular risks.

Author's summary: Extended melatonin use for sleep may significantly increase the risk of heart failure and death, urging caution among regular users and healthcare providers.

www.heart.org — 2025-11-04