Popular Sleep Supplement Could Be Harming Your Heart, Doctors Warn

A preliminary five-year study of over 130,000 adults with insomnia revealed a significant association between long-term melatonin use (over one year) and an increased risk of heart failure and all-cause mortality. Individuals using melatonin for extended periods demonstrated a 90% higher chance of incident heart failure, were 3.5 times more likely to be hospitalized for the condition, and nearly twice as likely to die from any cause. While researchers emphasize that this is an association requiring further investigation, these findings, slated for presentation at the American Heart Association’s Scientific Sessions 2025, raise critical cardiovascular safety concerns for a widely used, often unregulated, over-the-counter supplement.

Analysis

A recent preliminary five-year study, encompassing over 130,000 adults with insomnia, has identified a significant association between long-term melatonin use (over one year) and elevated cardiovascular risks and all-cause mortality. Specifically, individuals using melatonin for extended periods exhibited a 90% higher chance of incident heart failure, were 3.5 times more likely to be hospitalized for the condition, and nearly twice as likely to die from any cause compared to non-users. These findings, slated for presentation at the American Heart Association’s Scientific Sessions 2025, introduce substantial safety concerns for a widely consumed over-the-counter supplement.

The study underscores potential implications for the supplement industry, particularly given the unregulated status of melatonin products in markets like the United States, where purity and dosage can vary significantly. The strongly negative sentiment and cautious tone surrounding these findings suggest increased scrutiny from health authorities and consumers, potentially leading to calls for stricter regulation or labeling requirements for melatonin supplements. This could impact manufacturers and distributors of these products.

However, the research acknowledges several limitations, including the inability to establish a direct cause-and-effect relationship and the potential underrepresentation of over-the-counter users in the melatonin group due to data collection methods. The study also lacked information on insomnia severity or other psychiatric disorders, which could confound results. Despite these caveats, the consistent and significant increases in adverse health outcomes warrant further investigation into melatonin's long-term cardiovascular safety.

Key Decisions for Investors

• Investors should closely monitor regulatory developments concerning over-the-counter melatonin, particularly in jurisdictions like the U.S. where it is currently unregulated, as stricter oversight could impact market access and product liability for manufacturers.
• Evaluate portfolio exposure to companies involved in the production or distribution of melatonin supplements, considering potential sales declines or increased litigation risk if these preliminary findings are substantiated by further research.
• Track the progress of subsequent clinical trials and research into melatonin's long-term cardiovascular effects, as definitive causation could fundamentally alter consumer perception and market demand for sleep aids.