Washington, DC—Melatonin supplements are in the spotlight following news of a preliminary study presented at the American Heart Association Scientific Sessions 2025. The study associates the sleep-support supplements with a higher risk of heart failure diagnosis, heart failure hospitalization, and death from any cause in chronic insomnia. Researchers found the associations after reviewing five years of health records for more than 130,000 adults with insomnia who had used melatonin for at least a year. The findings do not prove a cause-and-effect relationship, but the researchers content that they raise safety concerns about the use of melatonin, and may warrant more research.
“Melatonin supplements may not be as harmless as commonly assumed,” said Ekenedilichukwu Nnadi, M.D., lead author of the study and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care in Brooklyn, NY, in the American Heart Association press release. “If our study is confirmed, this could affect how doctors counsel patients about sleep aids.”
The American Heart Association said in its announcement of the research that the study is an abstract that has not been peer-reviewed, and the findings are considered preliminary. Still, widespread media coverage of the research abstract may cause consumer concerns, and industry leaders were quick to put the findings into perspective.
The Council for Responsible Nutrition (CRN) urged all stakeholders to interpret the preliminary findings with caution and context. “As the American Heart Association itself notes, this research represents early, non–peer-reviewed data that cannot establish cause and effect,” CRN said in a statement. “Chronic insomnia—a condition shared by all study participants—may itself be a contributing factor to heart health outcomes, raising more questions than answers.”
The Natural Products Association (NPA) said the American Heart Association’s announcement failed to recognize that supplements sold in the U.S. are not intended to treat, cure, or prevent disease, per language in the Dietary Supplement Health and Education Act of 1994 (DSHEA). “We recommend that consumers with chronic sleeplessness and other chronic diseases always consult with their physicians to properly diagnose and treat their medical conditions,” said Daniel Fabricant, Ph.D., President and CEO of NPA. “The preliminary study examined whether melatonin use alters the risk of heart failure in chronic insomnia patients, which is not the supplement industry’s target population. Furthermore, the established literature demonstrates that short-term use of melatonin is safe. NPA agrees that consumers should not take melatonin supplements for chronic insomnia without a proper indication and in close consultation with a medical professional.”
CRN noted that, as a report in The Washington Post [subscription required] explains, quality sleep is critical for cardiovascular health, and that individuals who sleep poorly tend to have higher heart rates, higher blood pressure, and experience more cardiovascular events. “Therefore,” CRN said, “these findings are unlikely to apply to healthy adults who use melatonin dietary supplements occasionally for sleep support.”
CRN also pointed out that its voluntary melatonin labeling guidelines, adopted in 2024, recommend upper dosage levels and include advisory statements such as “For occasional and/or intermittent use only” and “Consult a healthcare professional if you are experiencing long-term sleep difficulties.”
A closer look at the preliminary study
Researchers in the preliminary segmented people into two groups:
- A “melatonin group” with subjects who had chronic insomnia and had used melatonin for at least one year, based on their electronic health records;
- A “non-melatonin group” with subjects who had insomnia and did not have melatonin recorded in their medical records.
“The study cited several limitations, including that the patient database did not include countries (including the U.S.) that don’t require a prescription for melatonin,” NPA explained. “Individuals who took over-the-counter melatonin supplements in the U.S. or other countries that don’t require a prescription would fall in the non-melatonin group, the American Heart Association said. This limitation raises additional questions about whether there is an actual cause-and-effect relationship and emphasizes that the study did not focus on the occasional use of melatonin for sleeplessness or other conditions, or FDA-regulated supplements containing versions of the hormone.”
CRN noted that additional study limitations include a lack of data on melatonin dose, insomnia severity, and psychiatric comorbidities. Along with the potential unrecorded supplement use among control participants, these factors may have distorted the apparent association.
Dietary supplements not regulated?
NPA also expressed disappointment in the American Heart Association for stating that over-the-counter supplements in the U.S. “are not regulated.” Setting the record straight on this common misconception, NPA reported: “Dietary supplements—including products containing melatonin—are subject to cGMPs (current good manufacturing practices) to confirm their identity, purity, strength and composition and that they contain no harmful adulterants. FDA inspects hundreds of supplement companies every year to review their manufacturing processes, and NPA has been committed to ensuring that its members follow the cGMPs applicable to dietary supplements since the final rule was promulgated in 2007.”
Melatonin safety
Melatonin has well-established short-term uses for regulating sleep timing and circadian rhythm, CRN said. “Decades of consumer experience and multiple clinical studies indicate that low-dose, short-term supplementation is safe for healthy adults when used as directed. The observational data presented at AHA do not alter that safety profile.” That said, noted that it supports ongoing scientific research to better understand long-term use patterns of all dietary supplements and welcomes rigorous, peer-reviewed investigations that contribute to evidence-based guidance, adding, “However, no single study—especially a preliminary abstract—should serve as the basis for broad conclusions or alarmist headlines about dietary supplements.”
Consumers who use melatonin should consult their healthcare providers, CRN said, particularly if they have cardiovascular concerns, before making any changes to their regimen. The trade group also spotlighted a quote from study author Dr. Ekenedilichukwu Nnadi in The Washington Post: “The takeaway isn’t that melatonin is ‘bad’ or that everyone should stop taking it. It’s that we shouldn’t assume something is risk-free just because it’s natural or sold over the counter.”
NPA’s Dr. Fabricant also stressed the work the industry does to help ensure safety of supplement: “While NPA supports further research to test the long-term safety of melatonin for the heart, it’s important to note that this preliminary study focused on a disease population. We do not promote the use of melatonin supplements to treat chronic insomnia or any other disease. NPA and its members take very seriously the industry’s responsibility to manufacture quality products based on cGMP requirements that FDA enforces. This is part of the robust regulatory framework created over 30 years ago under DSHEA, which created a clear distinction between products to support health and wellness and those to treat disease, the subject of the preliminary study announced by the American Heart Association.”
