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

A preliminary study presented at the American Heart Association’s Scientific Sessions 2025 indicates that long-term melatonin use (over one year) by adults with chronic insomnia is associated with a significantly elevated risk of heart failure diagnosis, hospitalization, and all-cause mortality. Analyzing over 130,000 electronic health records, the research found long-term users had a 90% higher chance of incident heart failure and nearly double the all-cause mortality rate compared to non-users. These findings, though preliminary and not establishing causation, raise substantial safety concerns for the widely available, unregulated supplement and underscore the need for further cardiovascular safety research.

Analysis

A preliminary study presented at the American Heart Association’s Scientific Sessions 2025 links long-term melatonin use to significantly elevated cardiovascular risks. Adults with chronic insomnia using melatonin for over a year showed a 90% higher chance of incident heart failure and were nearly 3.5 times more likely to be hospitalized for the condition. These findings, while preliminary and not peer-reviewed, challenge the perception of melatonin as a harmless over-the-counter sleep aid.

The study also reported long-term melatonin users were almost twice as likely to die from any cause over a five-year period. This raises substantial safety concerns, particularly given melatonin's unregulated status in markets like the U.S., where product strength and purity can vary widely. Such associations could prompt increased regulatory scrutiny and shift consumer behavior.

Key limitations include the inability to fully distinguish between prescription and over-the-counter use, and the absence of data on confounding factors like insomnia severity or other psychiatric disorders. Despite these caveats, the research underscores a critical need for robust, peer-reviewed studies into melatonin's long-term cardiovascular safety. This could significantly impact the broader sleep aid and supplement market.

Key Decisions for Investors

• Monitor regulatory developments concerning over-the-counter melatonin supplements, as increased scrutiny or new labeling requirements could impact manufacturers.
• Evaluate investment exposure to companies heavily reliant on melatonin sales, given potential shifts in consumer perception and demand due to safety concerns.
• Consider the potential for increased demand for regulated, prescription sleep aids, which could benefit pharmaceutical companies in that sector.
• Track the progress of confirmatory, peer-reviewed research on melatonin's long-term cardiovascular effects, as definitive findings would significantly shape market outlooks.