A recent study has raised concerns about the long-term use of melatonin supplements, linking it to a higher risk of heart failure. Sleep experts are advising those who use melatonin regularly to consult with sleep professionals for guidance and to consider the latest research when addressing sleep issues.
“Melatonin is helpful for some specific situations, such as jet lag and delayed sleep-wake phase disorder,” said Dr. Carolyn D’Ambrosio, a pulmonologist and certified sleep medicine specialist at the University of Miami Health System. “But we feel strongly that daily melatonin is not needed. Taking it is not completely benign.”
While previous studies have shown mixed results regarding melatonin’s safety and effectiveness, many in the medical community previously considered it safe or even protective for cardiovascular health. Some small clinical trials suggested benefits like lower nighttime blood pressure and reduced inflammation, but these effects may be short-lived.
Melatonin is a hormone produced by the pineal gland in the brain that helps regulate the body’s sleep-wake cycle. It also plays roles in immune system regulation, blood pressure control, bone formation, and reproductive function.
The supplement gained popularity after being marketed in the 1990s. According to a report from the National Institutes of Health (NIH), adult use of melatonin supplements in the U.S. increased more than fivefold between 1999 and 2018—from 0.4% to 2.1%—and sales grew from $62 million in 2003 to over $800 million by 2020 (https://www.nih.gov/news-events/nih-research-matters/use-melatonin-supplements-rising-among-adults).
Use among children has also risen; up to 20% of kids under age 14 reportedly receive melatonin regularly, according to a 2023 article in JAMA Pediatrics.
Dr. D’Ambrosio noted that factors such as excessive screen time, irregular schedules, stress, caffeine intake, alcohol consumption, and lack of exercise contribute to poor sleep habits—a trend driving increased reliance on supplements like melatonin.
Because melatonin is available over-the-counter in the U.S., many assume it is safe due to its natural origin. However, Dr. D’Ambrosio warned about side effects including daytime drowsiness, headaches, vivid nightmares, and nausea.
The lack of regulation by the U.S. Food and Drug Administration means actual melatonin content can differ significantly from what labels indicate. Experts recommend starting with low doses (0.5–1 mg), but many users take more than 5 mg nightly.
The new study was presented at the American Heart Association’s Scientific Sessions in November 2025 but has not yet been peer-reviewed or published. It found that people who used melatonin supplements for over one year had a 90% higher risk of heart failure compared to non-users; they were also more likely to be hospitalized for heart failure or die during the study period.
Dr. D’Ambrosio commented: “Cardiologists are now our number one referral source. Sleep and heart health are closely linked.” She explained that insufficient sleep increases risks for high blood pressure, stroke, and other cardiovascular problems.
She cautioned that further randomized controlled trials are necessary before drawing definitive conclusions about causality between long-term melatonin use and heart failure risk.
For those seeking better sleep quality without relying on supplements, Dr. D’Ambrosio recommended:
– Practicing good sleep hygiene with consistent schedules.
– Creating relaxing bedtime routines.
– Exercising during the day.
– Spending time outdoors in natural light.
– Limiting naps late in the day.
– Consulting board-certified sleep specialists if problems persist; cognitive behavioral therapy is now considered first-line treatment for chronic insomnia.
“We spend about one-third of our lives sleeping,” Dr. D’Ambrosio said. “That should make people realize how important sleep is. It’s the foundation of good health.”
