Mar 04, 2026
3 min read
A study on the popular sleeping pill has some scientists worried about long-term use.
A study of a popular sleep aid has some scientists worried about long-term use.
A recent analysis of adults with insomnia, which has not yet been peer-reviewed, found that those prescribed melatonin for more than a year had an increased risk of heart problems.
Among more than 130,000 adults in several countries, those given long-term melatonin had an 89 percent higher risk of heart failure over five years and were twice as likely to die from any cause, compared to those not prescribed.
Watch the clip below for a summary of the findings:
The results are preliminary and should not change current health recommendations.They do not mean that melatonin, the fourth most common natural product taken by US adults, has dangerous effects.
What the results suggest is that long-term use of melatonin needs more research to make sure it's safe.
Melatonin is generally safe and well tolerated for short-term use among those who are not pregnant or breastfeeding.This means about 1-2 months.
There are limited studies on the effects of supplements beyond this period, a situation that some researchers say should be addressed, especially given the growing popularity of supplements.
The study was presented last November at the American Heart Association's Scientific Meeting.
"Melatonin supplements may not be as harmless as commonly believed," medical scientist Ekenedilichukwu Nnadi of SUNY Downstate/Kings County Primary Care in New York said at the time.
"If our study is confirmed, it could impact how doctors advise patients about sleep aids."
A melatonin supplement mimics the hormone naturally produced by the brain to keep the body clocks correct.Taking this supplement throughout the day can make some people fall asleep and stay asleep.
In the United States and many other countries, melatonin supplements are available over the counter, meaning patients can take them without a doctor's prescription or supervision of dosage or duration of use.
Although some studies suggest that long-term use of melatonin is safe, comprehensive research is lacking.
Among other countries, a recent study by Nnadi and colleagues in the United States looked at the electronic health records of adults in the United States and the United Kingdom, where melatonin is only available as a prescription.
A secondary analysis found that those who took melatonin for more than a year were 3.5 times more likely to be hospitalized for heart failure than those who did not take melatonin.
In addition, the risk of dying from any cause increased between the groups from 4.3% to 7.8%.
The research is concerning, but the conclusions should be treated with caution.There is a serious limitation in the research methodology.
Participants were not identified in their melatonin use.Their prescriptions are used to measure who is taking something.This means that a control group (those who did not take melatonin) could include, for example, people in the US who take melatonin without a prescription.
Carlos Egea, President of the Spanish Federation of Sleep Medicine Societies, who was not involved in the study, noted this caveat in an expert reaction to the research.However, he still takes the associations of the study seriously.
"These findings challenge the concept of melatonin as a benign chronic treatment and only highlight the need for prospective trials with a controlled group to elucidate its safety profile," argued Egea.
Related: Study Links 5 Sleep Subtypes to Different Health and Lifestyle Patterns
Even in the short termMelatonin can also have downsides that many users are not aware of. For example, a non-fatal overdose in an Australian child has raised questions about the supplement's safety profile for certain age groups.
Melatonin products may be based on the natural hormone, but that doesn't mean there are no risks.
The findings were presented at the American Heart Association Scientific Sessions.
An earlier version of this article was published in November 2025
