MELATONIN IN THE NEWS

On November 3, 2025, a news release was issued by the American Heart Association newsroom entitled “Long-term use of melatonin supplements to support sleep may have negative health effects,” which highlighted a particular study abstract (MP2306) to be showcased at the American Heart Association Scientific Sessions in New Orleans, November 7-10, 2025. The release highlighted some research findings from this abstract, namely the following:

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• A review of health records from a global database of patient data was conducted for 5 years, encompassing 130,828 adults (average age, 55.7 years; 61.4% women) with insomnia.

• For adults who had used melatonin prescribed to them (versus those who were in the “non-melatonin” group, who had not had melatonin prescribed to them), there were greater rates of heart failure, hospitalization for the condition, and all-cause mortality in this group that had used melatonin.

• The study was not causal in nature, but an association. Therefore, no valid cause-and-effect relationship could be established.

• There was caution expressed about potential “safety concerns” about using melatonin as a supplement, and the need for more research on melatonin and cardiovascular safety.

 

Here are some points to note with respect to the abstract:

1. Research abstract vs. publication: This is a research abstract without all the details related to the study. Specific information would assist in forming the context of understanding, including the dose of melatonin supplementation, concurrent medication use, timing of use, format of supplement, and even the general health status of the population. Therefore, it is difficult to assess the implications of this research without having a peer-reviewed publication in a scientific journal. 

2. Population matters: The release mentions that the researchers had categorized people with chronic insomnia who used melatonin supplements long-term (one year or more, as documented in their electronic health records) and those who never had melatonin recorded anywhere in their medical records. This point suggests the following important points about the database and records used for analysis: 

   • It included people in countries that require a prescription for melatonin (e.g., the United Kingdom) and countries that do not need a prescription (e.g., the United States); 

   • The people seeking a prescription likely had health conditions warranting medical assistance for relieving insomnia, which can have several underlying root causes, including depression, anxiety, and even cardiovascular presentations; 

   • The prescription use most likely implies that a higher dose of melatonin was used (~3-6 mg or even higher); 

   • It remains unknown as to whether the “non-melatonin group” had ever used melatonin before, as its use was not documented. 

3. Long-term safety: A researcher's quote suggested that melatonin supplements “may not be as harmless as commonly assumed.” While melatonin has been well-researched for decades, with thousands of peer-reviewed studies, even regarding cardiometabolic health, there is still much nuance regarding the individual for whom it is used and whether the proper dose, format, and timing have been accounted for. Of course, there could also be medication interactions that would have needed to be investigated. Indeed, the long-term safety of higher-dose melatonin supplements has not been reviewed extensively; however, based on the available data, the American Academy of Sleep and the National Center for Complementary and Integrative Health suggest that the use of melatonin is generally safe.

 

Overall Takeaways

• The study details are necessary for a better understanding of the research findings' implications.

• Several published studies over the past few decades have indicated that melatonin supplementation may be beneficial for various health-related mechanisms, including heart health, by enhancing antioxidant activity, promoting a healthy inflammatory response, and supporting mitochondrial function. 

• The dose can “make the poison”; therefore, it is best to stay low and go slow with physiological doses of melatonin supplements if they are to be used. A physiological dose would be under 1 mg, and in middle age, it would be approximately 0.3-0.5 mg. 

For education only, not medical advice. Work with a qualified provider before beginning or changing any supplement routine.

Authored by Deanna Minich, PhD; Reviewed by Kim Ross, DCN