Popular Sleep Supplement Linked to Significant Heart Risk
A major new study has delivered alarming findings about melatonin, revealing that long-term use of the common sleep aid could dramatically increase the risk of heart failure. Research presented at the American Heart Association's 2025 Heart Disease and Stroke Statistics meeting indicates that patients taking melatonin for a year or more face approximately a 90 per cent higher chance of developing heart failure over five years compared to non-users.
Study Details and Startling Findings
Researchers conducted an extensive analysis of health records spanning five years, examining data from over 130,000 adults with insomnia. The study compared patients who had taken melatonin for at least one year against those with similar sleep issues who had never used the supplement. The results revealed that melatonin users were 3.5 times more likely to be hospitalised for heart failure than their counterparts who didn't take the supplement.
Ekenedilichukwu Nnadi, one of the study authors, expressed surprise at the consistency of the findings. "Melatonin supplements are widely thought of as a safe and 'natural' option to support better sleep, so it was striking to see such consistent and significant increases in serious health outcomes, even after balancing for many other risk factors," Dr Nnadi stated.
Regulatory Concerns and Medical Warnings
The research team discovered that even patients who had just two melatonin prescriptions filled 90 days apart showed a similar elevated risk of heart failure. This finding raises particular concerns given that melatonin is available over-the-counter in many countries, including the United States, meaning consumers can purchase it without medical supervision.
Study co-author Marie-Pierre St-Onge highlighted the prescribing paradox, noting "I'm surprised that physicians would prescribe melatonin for insomnia and have patients use it for more than 365 days, since melatonin, at least in the US, is not indicated for the treatment of insomnia." She emphasised that "people should be aware that it should not be taken chronically without a proper indication."
The researchers cautioned that their investigation has limitations, including insufficient data about participants' insomnia severity and potential psychiatric conditions. Dr Nnadi clarified that "While the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship." The team stresses that more research is urgently needed to properly assess melatonin's cardiac safety profile.
