Long-term use of melatonin supplements linked to higher risk of heart failure and death

A preliminary study slated for presentation at the American Heart Association's Scientific Sessions 2025 indicates that long-term melatonin use is associated with significantly increased risks of heart failure diagnosis (90% higher), heart failure hospitalization (3.5x), and all-cause mortality (nearly 2x) in chronic insomnia patients. These findings challenge the perception of melatonin as a benign over-the-counter sleep aid, potentially leading to shifts in consumer behavior, increased regulatory scrutiny of the unregulated supplement market, and revised medical guidance, which could impact manufacturers and distributors of such products.

Analysis

A preliminary study slated for presentation at the American Heart Association's Scientific Sessions 2025 indicates a significant association between long-term melatonin use and adverse cardiovascular outcomes in chronic insomnia patients. The study found a 90% higher chance of incident heart failure, a 3.5 times higher likelihood of heart failure hospitalization, and nearly double the all-cause mortality over five years for long-term users compared to non-users. These findings challenge the widely held perception of melatonin as a benign sleep aid.

This research highlights potential risks associated with a widely available, over-the-counter supplement that lacks federal regulation in markets like the U.S., leading to variability in product strength and purity. The results could prompt increased scrutiny from health authorities and potentially shift medical guidance regarding chronic melatonin use.

While the study acknowledges limitations, including the inability to prove direct causation and potential misclassification of OTC users, its consistent and significant findings warrant attention. The implications extend to the broader dietary supplement market, potentially impacting consumer demand and regulatory frameworks for sleep-aid products.

Key Decisions for Investors

• Investors should monitor potential regulatory responses to these findings, particularly concerning the unregulated over-the-counter supplement market, as increased scrutiny could impact manufacturers and distributors.
• Evaluate exposure to companies heavily reliant on melatonin or similar 'natural' sleep aid sales, as consumer demand may shift due to heightened safety concerns.
• Consider opportunities in pharmaceutical companies developing regulated, evidence-based treatments for insomnia and cardiovascular health, which may benefit from a re-evaluation of current sleep aid practices.