While melatonin is seen as a natural and safe supplement to improve sleep quality, a recent study revealed that its long-term use may involve serious health risks.
Extensive analyses, including more than 130,000 adults suffering from chronic insomnia, showed that people who took melatonin for a year or more were more likely to develop heart failure, require hospitalization, and even die, compared to other patients with similar conditions but who did not take the supplement.
Melatonin Risks
This study, which was presented at the American Heart Association’s Scientific Conference for 2025, is the first of its kind to assess the long-term use of melatonin in reality.
Although the study does not prove a direct causal relationship, the results were consistent across various analyses, prompting researchers to call for more caution and more rigorous studies.
Melatonin is a natural hormone secreted by the pineal gland that regulates the sleep-wake cycle, and the synthetic version of it is sold in the United States as a dietary supplement without the need for a prescription. However, the strength and purity of these supplements vary because they are not strictly controlled like drugs.
According to Ikenna Nnadi, a resident physician in internal medicine at SUNY Downstate: “Melatonin may not be as safe as it is believed to be, and if our results are confirmed, it may change the way doctors advise their patients.”
During a 5-year follow-up period, melatonin users were 90% more likely to develop heart failure and had a lower chance of survival compared to people who did not use it.
Researchers emphasize that these findings do not call for panic, but rather for caution, and advise patients to avoid using melatonin for extended periods without consulting a doctor, and to consider approved behavioral treatments for insomnia before resorting to supplements.
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