An analysis of five-year health data from over 130,000 adults suffering from insomnia who had been taking melatonin for at least a year indicated that these individuals were at an increased risk of being diagnosed with heart failure, needing hospitalization for the condition, or dying from any cause.
Long-term use of melatonin supplements, often utilized to enhance sleep and treat insomnia, was linked to a higher risk of heart failure diagnosis. Image credit: Gemini AI.
Melatonin is a hormone naturally generated by the pineal gland, aiding in the regulation of the sleep-wake cycle.
Levels of melatonin rise in darkness and fall during daylight.
Synthetic hormones, chemically identical to natural melatonin, are frequently prescribed to address insomnia (difficulties in initiating or maintaining sleep) and jet lag.
This supplement is widely available over-the-counter in several countries, including the United States.
In the recent study, researchers identified individuals with long-term melatonin use (defined as over a year recorded in electronic health records) as part of the melatonin group.
Conversely, those without any recorded use of melatonin in their medical history were classified as the non-melatonin group.
“The perception that melatonin supplements are harmless may not be accurate,” asserts Dr. Ekenedirichukwu-Nnadi from the State University of New York Downstate/Kings County Primary Care.
“If validated, our findings could significantly impact how healthcare providers counsel patients regarding sleep aids.”
Although melatonin supplements are marketed as safe sleep aids, there is insufficient evidence regarding their long-term cardiovascular safety, prompting researchers to investigate whether melatonin use elevates the risk of heart failure, particularly in chronic insomnia patients.
Heart failure, which arises when the heart is unable to pump sufficient oxygenated blood for the body’s organs to operate effectively, affects 6.7 million adults in the United States, according to the American Heart Association’s 2025 Heart Disease and Stroke Statistics.
The researchers utilized a large international database to analyze five years of electronic health records of adults with chronic insomnia who had documented melatonin use exceeding one year.
They were compared with colleagues in the database who also suffered from insomnia but did not have melatonin recorded in their medical files.
Participants with a prior heart failure diagnosis or those prescribed other sleep medications were excluded from the study.
The analysis revealed that among insomnia sufferers, those whose records indicated long-term melatonin use (over 12 months) were roughly 90% more likely to develop heart failure over five years compared to non-users (4.6% vs. 2.7%, respectively).
Similar outcomes (an 82% higher incidence) were observed for individuals who received at least two melatonin prescriptions spaced 90 days or more apart.
In a further analysis, researchers noted that melatonin users were nearly 3.5 times more likely to be hospitalized for heart failure compared to non-users (19.0% vs. 6.6%, respectively).
Melatonin group participants were almost twice as likely to die from any cause over a five-year duration compared to those in the non-melatonin group (7.8% vs. 4.3%, respectively).
“Melatonin supplements are generally regarded as a safe, ‘natural’ solution for improving sleep quality, so the consistent and significant rise in serious health issues was unexpected,” stated Dr. Nadi.
“Since melatonin isn’t officially approved for treating insomnia in the U.S., it’s surprising that physicians would prescribe it for more than 365 days,” remarked Dr. Marie-Pierre St-Onge from Columbia University.
“While melatonin is available as an over-the-counter supplement in the U.S., individuals should be cautious about using it chronically without proper guidance.”
The research findings are expected to be presented at an upcoming conference this week at the American Heart Association 2025 Academic Session.
Source: www.sci.news
