Melatonin: Stay the Course
As we continue to examine the results that appeared to suggest that the chronic use of melatonin in people diagnosed with insomnia could result in an increased risk of a diagnosis of heart failure, heart failure hospitalizations, and death from all causes, let’s put the unreviewed abstract in perspective. One correction from Tuesday. The researchers did not track the subjects for five years; the gathered data from the past five years. That’s an important difference
The simplest way to is to convert the percentage of risk into real percentages. The study reported that the risk of developing heart failure was over 90%. That’s true, but it’s based on the percentage of insomniacs that didn’t use melatonin at 2.7% versus 4.6% in those that did use melatonin. The same logic was used for hospitalizations (19.0% vs. 6.6%), and mortality (7.8% vs. 4.3%). It still seems like a significant risk, but there’s one more number that’s important: the total number of subjects in the study.
Insomnia: The Numbers
In the United States, the average number of adults that are diagnosed with insomnia is 12%. With 268 million adults in the U.S., that means that 32.2 million people have chronic insomnia. The percentage diagnosed is about the same in all high-income countries around the world. The researchers used a database that claims to have 150 million de-identified electronic medical records in its database, so how did the number of subjects get to only 120,000? It should have been at least 15 million.
Yes, the subjects were matched for a variety of criteria including age, gender, medications, and other factors but still, that’s an awful lot of lost subjects. Even without the diagnosis of insomnia, other diagnoses such as depression and other mental health diagnoses result in insomnia. They can also predispose people to heart failure as well. Those subjects would also have been lost.
The most significant information that was not collected was any data on over-the-counter melatonin use. To their credit, they do cite that as an issue, but there are no data as to how much melatonin was actually used by the subjects who took melatonin. There’s no record of melatonin use by people in the non-melatonin group if they didn’t report it as a supplement they use to their physician. There are more questions, but that’s enough to call the results into question.
The Bottom Line
Perhaps after the peer-review process, the data collection will be more clear. But as for right now, the best thing that could be said is that they distributed a great press release that caused a lot of concern. But as for actual research evidence? There’s no reason to modify melatonin use at this point. However, it’s always a good idea for you to report any supplements you’re taking to your healthcare provider.
What are you prepared to do today?
Dr. Chet
Reference: American Heart Association Scientific Sessions 2025, Abstract MP2306
