Long-term Use of Melatonin Supplements and Health Risks
A review of five years of health records involving over 130,000 adults with insomnia who used melatonin for at least a year found increased risks linked to its long-term use.
Key Findings from Recent Research
- Users of melatonin supplements had a higher chance of being diagnosed with heart failure.
- There was an increased likelihood of hospitalization due to heart failure among these individuals.
- The study also noted a higher rate of death from any cause in people with chronic insomnia using melatonin supplements.
Study Presentation and Context
This preliminary study was presented at the American Heart Association’s Scientific Sessions 2025 held from November 7 to 10 in New Orleans, a major event for sharing advances in cardiovascular science.
About Melatonin
Melatonin is a hormone produced naturally by the pineal gland that regulates the sleep-wake cycle, increasing at night and decreasing during the day.
Synthetic melatonin supplements, chemically identical to the natural hormone, are commonly used to help with insomnia and jet lag.
These supplements are widely available over the counter in many countries, including the U.S.
Concerns with Over-the-Counter Supplements
In the United States, melatonin supplements do not require government approval before sale, leading to variability in strength and purity among different brands.
Melatonin "helps regulate the body’s sleep-wake cycle. Melatonin levels increase during darkness and decrease during daylight."
According to the study, "Long-term use of melatonin supplements ... was associated with a higher risk of heart failure diagnosis, heart failure hospitalization and death from any cause in chronic insomnia."
Author’s summary: Long-term melatonin supplementation, commonly used for sleep issues, may increase heart failure risks and mortality, highlighting the need for cautious use and further research.