A new one preliminary study raises concerns about the long-term use of melatonin supplements among people with chronic insomnia. A study presented in November 2025 at the American Heart Association Scientific Sessions in New Orleans suggests that melatonin use for a year or more may be associated with a higher risk of heart problems.
The study was not peer-reviewed, so the findings should be viewed as early evidence rather than definitive answers. The results highlight the need for more research into how melatonin affects long-term health.
That’s what research has found
Researchers reviewed five years of electronic health records of 130,828 adults diagnosed with insomnia. The average age was 55.7 years and about 61% were women. They compared people with long-term melatonin use, that is, at least 12 months documented in their medical records, with similar adults who had insomnia but no record of melatonin use.
The main analysis found that adults with chronic insomnia who used melatonin long-term were about 90% more likely to develop heart failure over five years than adults who did not take melatonin (4.6% vs. 2.7%).
The study also found that people taking melatonin were about 3.5 times more likely to be hospitalized for heart failure than those not taking melatonin (19.0% versus 6.6%).
The researchers note some limitations. The database includes countries where melatonin requires a prescription and places like the US where it does not. Because the study relied on prescriptions and medication use records, many people taking melatonin by prescription were counted as consumers. This means that the findings may not fully reflect actual use.
What is melatonin?
Melatonin is a hormone that your body produces naturally. It helps regulate your sleep cycle by signaling when it’s time to sleep.
Melatonin supplements are widely available in the US, with dosages ranging from 1 to 10 milligrams. However, because melatonin is sold as a dietary supplement, it is not regulated by the FDA. This means that the content of the supplement may differ from what is stated on the product label.
A study 2017 The Journal of Clinical Sleep Medicine found that the content of melatonin in dietary supplements often differs from what is listed on the label. The results show that the melatonin content of more than 71% of the supplements differed from the label by more than 10%, ranging from 83% less to 478% more than the label. Levels varied even from batch to batch within the same brand.
Melatonin can be effective for certain circadian rhythm disordersbut there is no evidence that it works well as a general sleep aid. However, many people use it to self-treat insomnia.
Additional usage and safety tips
The use of melatonin has increased over the past two decades across all age groups, supporting this trend research shows a significant increase in reported supplement use among US adults from 1999 to 2018.
Since the pandemic, there has been an increase in emergency calls about melatonin overdose in children. In response, the American Academy of Sleep Medicine a health advice urges parents to seek medical advice before giving melatonin to children or adolescents.
Experts continue to be cautious, especially since supplement content varies widely and long-term effects remain unclear.
Understanding insomnia
Since many people use melatonin to manage insomnia, it helps to understand what insomnia is and how it is usually treated.
Chronic insomnia means having trouble falling asleep at least three times a week for three months or more. About 10% of adults experience it.
Treatment depends on the cause, but sleep experts recommend trying it healthy sleep habits first for short-term insomnia. But for chronic insomnia, lifestyle changes are often not enough.
American Academy of Sleep Medicine recommends cognitive behavioral therapy for insomnia, or CBT-I, as the first-line treatment for chronic insomnia in adults. CBT-I includes strategies to change unwanted thoughts and behaviors around sleep. Medication is usually reserved for people who cannot participate in CBT-I, who still have symptoms after treatment, or who need short-term help in combination with CBT-I.
Basic considerations
This new study found a link between long-term melatonin use and heart risk. It did not show that melatonin causes heart failure. More research is needed before experts can say whether long-term use of melatonin affects heart health.
Melatonin may seem like a simple solution to sleep problems, but it’s not risk-free and doesn’t help with insomnia in the first place. If you struggle with chronic sleep problems, talk to a health professional or get help from a sleep team accredited sleep center.
Medical review by Helena Scotland, MD
