Taking melatonin to fall asleep might come with an unexpected side effect, according to new research from the American Heart Association.
A review of health records from more than 130,000 adults found that people who used melatonin for a year or longer were significantly more likely to develop heart failure, be hospitalized for it, or die from any cause within five years.
The findings were presented on Monday at the association’s Scientific Sessions 2025 in New Orleans.
“Melatonin supplements may not be as harmless as commonly assumed,” Dr. Ekenedilichukwu Nnadi, the study’s lead author, said in a statement. “If our study is confirmed, this could affect how doctors counsel patients about sleep aids.”
This sounds like it’s probably a case of correlation != Causation. It’s probable that people taking it are more likely to have underlying conditions.
That is explicitly what the researchers say as quoted in the article
Yeah, but it’s helpful to have it posted here to provide common sense among the speculation in the comments.
I know that “linked to” does not formally claim causation and “might come with an unexpected side effect” is technically unfalsifiable, but I still think that journalists have a responsibility not to write such articles even when the researchers presenting the correlation are making an implausible claim that causation is likely.
This article does appropriately include some reasons to doubt the interpretation that melatonin causes heart failure, but nonetheless the very existence of the article will give members of the public the impression that there is good evidence that melatonin might be dangerous (which there isn’t). Readers depend on reporters’ judgement so many readers will think “If this isn’t important information, then why is it in the newspaper?”
Makes me think of the people who base their political opinions off little more than divisive headlines and click bait trash articles
"The study has several limitations. First, 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 may 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.
“Worse insomnia, depression/anxiety or the use of other sleep-enhancing medicines might be linked to both melatonin use and heart risk,” Nnadi said. “Also, while the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship. This means more research is needed to test melatonin’s safety for the heart.”"
Multidimensional Sleep Health: Definitions and Implications for Cardiometabolic Health: A Scientific Statement From the American Heart Association https://www.ahajournals.org/doi/epub/10.1161/HCQ.0000000000000139
I seem to be missing something. When I keyword search “melatonin” on the above paper, the word melatonin does not appear in the paper. It is a lengthy piece on many aspects of sleep on cardiovascular health, but does not appear to mention melatonin. I gather that this paper is still in peer review, and not to be presented until Nov. 7-10.
so tldr…people who need to take melatonin to sleep tend to have higher cardiac risk in the first place?
Apparently. Poor sleep is associated in this and other papers with increases in adiposity/ obesity, which is well understood to have impacts on CVD.
Typical correlation not causation bullshit from epidemiologists with no mechanism and everyone gets scared.
It’s also not uncommon for people in the UK to just order it from the USA, since it’s legal to do so for personal use.
okay but the wording there reads like the ring or something. less fearmongering, please! articles"
also american meds are typically not as regulated as european meds… which melatonin supplements were even examined?
questions
There’s also another thing that comes to mind: people taking melatonine are usually people with trouble sleeping, which is already a factor on heart failure.
Because dietary supplements aren’t regulated by the Food and Drug Administration, their potency and purity can vary widely between brands.
Experts emphasize that the study does not prove that melatonin directly causes heart problems. The analysis relied on prescription records, meaning many people who purchase melatonin over the counter may have been misclassified as nonusers.
Experts say more research is needed to determine whether melatonin itself contributes to heart problems or whether it simply signals deeper issues with sleep and cardiovascular health.
“The takeaway isn’t that melatonin is bad or that everyone should stop taking it,” Nnadi said. “It’s that we shouldn’t assume something is risk-free just because it’s natural or sold over the counter.”
Answers
Good sleep and I get to die?! What a miracle drug!
Here’s the original press release for anyone interested: https://newsroom.heart.org/news/long-term-use-of-melatonin-supplements-to-support-sleep-may-have-negative-health-effects
The most important sentence: “They were matched with peers in the database who also had insomnia but never had melatonin recorded in their health records. People were excluded from the analysis if they had previously been diagnosed with heart failure or had been prescribed other sleep medications.” There are a few other sentences describing how well the control group was matched. I think it was a well-designed study.
I think there is still a risk of bias present, though, because people who decide to take melatonin might have more severe insomnia compared to people who just decide to just “live with it” and are not using sleep aids.
The next step should be a randomized clinical trial looking at heart failure rate in patients with insomnia dosed with melatonin versus placebo and/or a different medication. Until then, correlation does not mean causation. I don’t think such a study will be done in the US because melatonin is considered a dietary supplement and is not subject to the same degree of regulation as medicine. Maybe in the UK, since melatonin is prescription only?
Article was soft paywalled with my adblocker enabled; here’s the actual press release
Does anyone remember the drinks that had melatonin called Marley’s mellow mood
I’ll be dead very soon then. Hooray!
Steven Strogatz studies networks and behavior and in his research about dreams, the brain needs about 3 pico grams of naturally created malatonin for sleeping. A pill may deliver over 3 million more than needed.
I’ve taken melatonin a few times and it always felt obvious that it was not contributing to a more restful and good sleep.
IMO they’re sold in too high doses and people take way too much. I take 1mg and I sleep through the night instead of waking up twice and possibly being unable to go back to sleep. If I take more than that, I have weird dreams and wake up groggy. It is commonly sold in 3mg, 5mg, 10mg doses. Crazy.
Same here. I tried multiple doses starting at 1mg, multiple time frames, it never did anything. But this is the world of supplements, where no one is actually verifying if what is on the label is actually in the bottle. Republicans have been defending this pseudo-medicine for decades by not regulating it.
