Melatonin has long been regarded as a safe and natural aid for improving sleep. However, two recent pieces of research are raising important questions about its long-term use in both adults and children.
New Findings on Heart Health in Adults
Preliminary research presented at the American Heart Association Scientific Sessions 2025 found that adults with chronic insomnia who used melatonin for at least one year had a significantly higher risk of developing heart failure over the following five years compared with similar insomnia sufferers who did not use melatonin.
The study analysed more than 130,000 adults from the TriNetX global health-records database. After matching participants for numerous health and demographic factors, researchers found that heart failure occurred in 4.6% of long-term melatonin users compared with 2.7% of non-users — representing approximately a 90% higher relative risk.
Long-term melatonin users also experienced higher rates of heart-failure-related hospitalisation and all-cause mortality. Researchers stressed that the study was observational and does not prove melatonin caused these outcomes. Other factors, including the severity of insomnia, anxiety, depression, or use of additional medications, may have influenced the results.
Nevertheless, the findings challenge the widespread assumption that melatonin is entirely harmless when used over extended periods and highlight the need for further investigation into its cardiovascular safety.
Growing Use Among Children
At the same time, researchers are expressing concern about the rapidly increasing use of melatonin in children and adolescents.
A review published in the World Journal of Pediatrics found that while melatonin can be beneficial for children with neurodevelopmental conditions such as autism spectrum disorder and ADHD, evidence supporting its routine use in otherwise healthy children remains limited.
Clinical studies suggest melatonin may help some children fall asleep faster and improve total sleep time. However, most studies have been relatively short-term, leaving important questions unanswered about long-term effects on development, puberty, metabolism, immune function, and neurological health.
Product Quality and Safety Concerns
Researchers also highlighted concerns regarding the quality and consistency of over-the-counter melatonin products. Independent testing has shown that actual melatonin content can vary substantially from the amount stated on product labels. Some supplements have even been found to contain unexpected ingredients.
Another growing concern is the increase in accidental melatonin ingestion among young children, particularly from gummy formulations that resemble sweets. Poison-control centres in several countries have reported rising numbers of such incidents.
A Hormone, Not Just a Supplement
Experts emphasise that melatonin should be viewed as a biologically active hormone rather than simply a benign dietary supplement. Although it plays a key role in regulating the sleep-wake cycle, it also influences other physiological systems, including metabolism, immunity, and reproductive function.
For adults, the emerging cardiovascular findings underscore the need for more rigorous long-term safety studies. For children, researchers recommend that melatonin be reserved for carefully selected cases and used under professional supervision.
Practical Recommendations
Current evidence suggests that melatonin can be useful when appropriately prescribed or recommended, particularly for specific sleep disorders and certain neurodevelopmental conditions. However, it should not be regarded as a first-line or indefinite solution to sleep problems.
Sleep experts continue to recommend behavioural strategies as the foundation of good sleep hygiene, including:
- Maintaining consistent sleep and wake times.
- Limiting screen exposure before bedtime.
- Creating a calm sleep environment.
- Addressing underlying causes of insomnia rather than relying solely on supplements.
Where melatonin is considered appropriate, experts advise using the lowest effective dose for the shortest necessary duration while monitoring for potential adverse effects.
Conclusion
Melatonin remains one of the most widely used sleep aids worldwide, yet significant gaps remain in our understanding of its long-term safety. New evidence linking prolonged use to increased cardiovascular risks in adults, together with concerns regarding widespread use in children and variable product quality, suggests a more cautious and evidence-based approach may be warranted until further research provides clearer answers.
Story Source:
American Heart Association. "Long-term melatonin use linked to 90% higher heart failure risk."
Melatonin use in the paediatric population: an evolving global concern. World Journal of Pediatrics, 2025