Melatonin a Risk to Your Heart Health???

Too often, highly flawed studies show some problem with a particular supplement. These are enthusiastically given to the media for propagation.  Always keep in mind that the pharmaceutical industry is looking for ways to sell you controlled substances, in this case, probably Ambien and friends.

Periodically we have to talk some friend down because of something they read online about a supplement they are taking. We always tell them not to get their health information from those sources. We always encourage periodic blood tests to keep track of key physiological markers. Personally, I take melatonin every night (3 mg), not so much for sleep but for the immune benefits I have experienced. If I take my melatonin, zinc, NAC, vitamins C &D, I just don’t get colds like I used to.

To summarize, a recent preliminary study presented at the American Heart Association's (AHA) Scientific Sessions in November 2025 claimed to find an association between long-term melatonin use and a significantly increased risk of heart failure, hospitalization, and mortality.

Take another look at the image that is attached to this blog. This is great example of correlation and not causation. A study might find that bent awnings have a high association with cats. It is obvious to you that the cat didn’t cause the awnings to warp.

Key Points of the Study

Researchers analyzed five years of electronic health records from more than 130,000 adults with chronic insomnia. Adults who used melatonin for a year or longer had an approximately 90% higher chance of developing heart failure compared with matched non-users. Long-term melatonin users were nearly 3.5 times as likely to be hospitalized for heart failure and nearly twice as likely to die from any cause during the 5-year period.

Important Caveats

“The database includes countries that require a prescription for melatonin (such as the United Kingdom) and countries that don’t (such as the United States), and patient locations were not part of the de-identified data available to the researchers. Since melatonin use in the study was based only on those identified from medication entries in the electronic health record, everyone taking it as an over-the-counter supplement in the U.S. or other countries that don’t require a prescription would have been in the non-melatonin group; therefore, the analyses will not accurately reflect this.

Hospitalization figures were also higher than those for initial diagnosis of heart failure because a range of related diagnostic codes may be entered for the hospitalization, and they may not always include the code for a new diagnosis of heart failure. The researchers also lacked information on the severity of insomnia and the presence of other psychiatric disorders.”

Association vs. Causation: The study found an association, but it did not prove that melatonin caused any of these heart problems. The need for a sleep aid may instead be a sign of underlying, unaddressed health issues, such as undiagnosed sleep apnea, depression, or anxiety, which themselves are risk factors for poor heart outcomes.

Preliminary Data: The findings are from a research abstract and have not yet been published as a full, peer-reviewed scientific manuscript. This means they are considered preliminary and require further investigation.

Study Limitations: The study relied on medical records that may not have captured over-the-counter melatonin use (as it's often unregulated in the U.S.), potentially skewing the data. Also, critical details like the specific dosage of melatonin used by participants are not yet available.

A quick analysis of PubMed shows over 3000 melatonin published studies.  Over a thousand of these show talk of some heart health factor, either in people or animals.  Therefore, there is a lot to know and the literature is not full of studies showing melatonin to be dangerous in modest doses as this news flash would seem to indicate. On the contrary, small doses of melatonin has been studied by many researchers and found predictable benefits. 

NuMedica Melatonin 3 mg 60 Lozenges  The melatonin I take

NuMedica Melatonin Liquid 2 oz  The melatonin my wife takes

DS 2025