Does Melatonin Raise Your Risk of Heart Failure? What the Study Behind the Headline Actually Shows

September 14, 2026

A headline came around again last week saying that people who take melatonin for a year or more have a 90 percent higher risk of heart failure. ScienceDaily ran it, and from there it moved across the usual health sites and morning shows. If you keep a bottle of melatonin on the nightstand, and roughly one in fifty American adults reported doing so in the last national survey to count, the number is alarming.

The study is real. Researchers presented it at the American Heart Association’s annual meeting in New Orleans in November, and the August coverage is a re-release of that same work. Nothing about it has changed since then. What has changed is that it reached a fresh audience, so the questions are arriving again.

I want to walk through what the researchers found, why the 90 percent figure means a great deal less than it appears to, and what I would tell someone sitting across from me who takes melatonin every night and is now wondering whether to stop.

What the study found

Researchers led by a chief resident in internal medicine at SUNY Downstate in Brooklyn searched a large international database of electronic health records for adults with a diagnosis of chronic insomnia. They found 130,828 of them. Half had at least one year of melatonin use recorded in their chart. No melatonin appeared anywhere in the other half. Anyone who already had heart failure was excluded, and so was anyone prescribed other sleep medicines such as the benzodiazepine family. Both groups were matched on about forty characteristics, including age, sex, blood pressure, body mass index, existing heart and nervous system conditions, and the medicines used to treat them. Then the researchers followed both groups for five years and counted who developed heart failure.

Heart failure showed up in 4.6 percent of the melatonin group and 2.7 percent of the comparison group. That gap is where the 90 percent figure comes from. It is a relative difference. In absolute terms it is about two extra cases per hundred people over five years. Hospitalization for heart failure ran about three and a half times as often in the melatonin group, 19 percent versus 6.6 percent. More of them died over the five years too, 7.8 percent versus 4.3 percent.

Hold onto that absolute number. It is the one that describes a person.

In a second pass they tightened the definition, counting only people with at least two melatonin prescriptions filled ninety days apart, and the heart failure gap held at about 82 percent. The signal did not wash out.

Even the lead author stayed measured. He said melatonin may not be as harmless as commonly assumed, and that if the finding is confirmed it could change how doctors counsel patients about sleep aids. That “if confirmed” is doing a lot of work, and the rest of this post is about why.

Why the number is weaker than it looks

Start with what kind of study this is. This one looked backward through medical records and compared two groups that already existed. A study like that can show that two things travel together. It cannot show that one causes the other, and the authors said so. This went out as a conference abstract, which means it has not been through the peer review a journal would require, and as of this writing no full paper has appeared.

Now look at who ends up in each group, because this is where the problem lives.

Melatonin is sold over the counter in the United States, next to the vitamins. Most people who take it never mention it to a doctor and it never enters their chart. So in an American medical record, “a year of documented melatonin use” describes an unusual person. It is someone whose insomnia was bad enough, or persistent enough, that a physician kept writing it down, or in some cases prescribed it, for twelve months or longer. That is not a typical patient. Those are people with worse sleep, and very likely more depression, anxiety, and other conditions that the researchers admit they could not measure.

The comparison group has the opposite problem. That group is full of people who were taking melatonin from the drugstore and simply never said so. A sleep medicine society president made exactly this point when the abstract came out. That “no melatonin” group very likely contained a large number of melatonin users. When your control group is contaminated with the exposure, the comparison stops meaning what it claims to mean.

Then there is the insomnia itself. Chronic insomnia, on its own, is associated with higher rates of heart failure. A large Norwegian study published in 2014 followed more than 54,000 adults for eleven years and found that people with all three major insomnia symptoms developed heart failure at about four and a half times the rate of people with none of them. That link probably runs through the stress hormone system, blood pressure that fails to dip at night, and the company insomnia keeps, such as depression and sleep apnea. Any study that compares people with severe, persistent insomnia against people with milder insomnia is going to find more heart failure in the first group. Melatonin may be a bystander here, marking how bad the insomnia is rather than causing anything.

Add the fact that the database mixes countries where melatonin is prescription-only, such as the United Kingdom, with countries where it is not, and that the researchers could not tell which patients came from where. Add that they had no information on how much anyone took, or whether the melatonin recorded was a 0.5 milligram tablet or a 10 milligram gummy. Dose is simply missing.

None of this proves melatonin is safe. It means this study cannot tell us whether it is dangerous.

An expert from the American Heart Association’s own sleep statement committee, when asked to comment, said she was surprised physicians would prescribe melatonin for insomnia for more than a year at all, since it is not an approved treatment for insomnia in the United States. That is a fair point about the practice of medicine. Those patients were also being managed in a way that is itself unusual.

What is actually known about melatonin and the heart

Melatonin is a hormone your own brain makes, released from a small gland in the evening as the light fades. Call it a timing signal more than a sedative. Its whole message is that night has arrived. Supplement versions carry the same molecule, usually in doses far larger than anything the brain produces.

For decades, the small studies that exist have pointed, if anywhere, in the direction of benefit for the heart. Melatonin has antioxidant properties in the laboratory. A pooled analysis of seven small trials found no overall effect on nighttime blood pressure. Slow-release forms did lower it, by about 6 points on the top number and 3 on the bottom. Fast-release moved it not at all. Fast-release is most of what sells over the counter here.

A randomized trial gave 10 milligrams a night to 92 people who already had a weakened heart muscle. After six months their blood marker of heart strain and their quality of life scores were better than the placebo group, and their pumping strength was unchanged. No harm signal appeared. That trial was small and short and nobody should build a treatment plan on it. These findings are worth knowing about because a 90 percent increase in heart failure would be an odd result for a molecule with that track record, and an odd result deserves a hard look before it is believed.

Where the real concern about melatonin supplements lies is somewhere else entirely. In the United States they are regulated as dietary supplements. Nobody checks what is in the bottle before it is sold.

A 2023 analysis published in a major medical journal tested twenty-five melatonin gummy products sold in this country. Twenty-two of them, close to nine in ten, were labeled inaccurately. Most held more melatonin than the label claimed, one of them three and a half times the stated dose, and one product contained no melatonin at all. If you take “3 milligrams” every night, you may be taking a great deal more, and the amount may vary from bottle to bottle. That is a legitimate reason for caution, and it has nothing to do with heart failure.

Melatonin is also not a very good insomnia treatment. Guidelines from the American Academy of Sleep Medicine suggest clinicians not use it for trouble falling or staying asleep. That is a weak recommendation resting on very low quality evidence, which tells you how thin the research is in both directions. Melatonin does have a reasonable role for shifting your body clock, which is why it can help with jet lag and with people whose sleep timing is out of step with the rest of the world. Taking it every night for years to treat ordinary insomnia is a different use, and the evidence that it works for that is thin.

What I would tell you

If you take melatonin most nights and you are otherwise healthy, I would not tell you to stop on the strength of this study. I would ask a different question, which is whether it is doing anything for you. Many people take it out of habit. A trial off it for two weeks answers the question at no cost.

Plenty of people are surprised by the answer.

If you have heart failure, or you have been told your heart’s pumping strength is reduced, this is worth a conversation at your next visit, whether that is with me here in Encinitas or with your own cardiologist. The study does not prove harm. Your medication list still deserves a look, and a supplement that may not be helping is an easy thing to remove.

If you take melatonin because you cannot sleep, the better use of your energy is to get the insomnia itself treated. First-line treatment for chronic insomnia is a structured behavioral program, usually four to eight sessions, that retrains the habits and the thinking that keep insomnia going. It works better than any pill, the benefit lasts after the sessions end, and it has no side effects. Most people have never been offered it. Ask for it by name.

And if you snore, wake up unrefreshed, or your partner has noticed you stop breathing at night, the thing to rule out is sleep apnea, which is common, very hard on the heart, and treatable. Some of the “insomnia” that ends up managed with a nightly supplement for years is sleep apnea that nobody has looked for.

Finally, if you keep taking it, buy a product that carries a third-party verification mark, use the lowest dose that does what you need, which for most adults is 0.5 to 3 milligrams rather than 10, and tell your doctor it is on your list. A supplement you never mention is one nobody can help you think about.

Where this leaves the science

This finding is a signal, and a signal from a database this large is worth following up. Proper follow-up would measure how much melatonin people actually take, over-the-counter included, account for how bad the insomnia is and what else is going on in a person’s life, and ideally randomize people to melatonin or placebo and watch their hearts. Nothing like that exists yet. Until it does, the fair summary is that people with insomnia bad enough to be treated with melatonin for a year have more heart failure than people with milder insomnia, and we do not know how much of that, if any, is the melatonin.

The coffee question went through a similar cycle of frightening headlines followed by a calmer reading of the evidence. So did calcium supplements. Hold onto the pattern. Things with settled evidence behind them for preventing heart failure are blood pressure control, not smoking, keeping weight and blood sugar in range, regular movement, and, for a great many people, treating the sleep apnea they did not know they had. A nightly gummy is not on that list in either direction.

Frequently Asked Questions

Does melatonin cause heart failure?

The study cannot answer that. It compared people whose medical records showed a year or more of melatonin use against people with no record of it, and found more heart failure in the first group. That design shows association, not cause. The melatonin group very likely had worse insomnia and more untreated conditions, and the comparison group very likely included people taking melatonin from the drugstore who never told a doctor.

How big was the difference in real terms?

Heart failure developed in 4.6 percent of the melatonin group and 2.7 percent of the comparison group over five years. The 90 percent figure is the relative difference between those two numbers. In absolute terms it is about two additional cases per hundred people over five years, and it is not known how much of that is explained by the melatonin rather than by the severity of the insomnia.

Should I stop taking melatonin?

If you are otherwise healthy, this study is not a reason to stop. It is a reasonable moment to ask whether the supplement is doing anything for you, and a two-week trial without it will tell you. If you have heart failure or reduced pumping strength, bring it up at your next appointment so your whole medication and supplement list can be reviewed.

Is there any evidence melatonin is good for the heart?

A pooled analysis of seven small trials found no overall effect on nighttime blood pressure, though the slow-release form lowered it by about 6 points on the top number. A randomized trial in 92 people with a weakened heart muscle found better scores on a blood marker of heart strain and on quality of life after six months, with no harm signal. None of that is strong enough to recommend melatonin for the heart, and none of it fits with a large increase in heart failure risk, which is one reason the new finding needs confirmation before it is believed.

What is the real safety problem with melatonin supplements?

Labeling. Melatonin is sold as a dietary supplement in the United States, and testing of twenty-five gummy products sold here found twenty-two of them inaccurately labeled, most holding more than the label stated and one of them three and a half times the stated dose. If you use it, choose a product with a third-party verification mark and use the lowest dose that works, which for most adults is 0.5 to 3 milligrams.

What works better than melatonin for insomnia?

A structured behavioral program for insomnia, usually four to eight sessions, is the recommended first-line treatment for chronic insomnia. It outperforms sleep medicines over the long run and has no side effects. If you snore or wake unrefreshed, a sleep study to look for sleep apnea should come first, because untreated sleep apnea is a major driver of heart disease and often gets mistaken for insomnia.

Why is a study from November in the news again?

The research was presented at the American Heart Association’s Scientific Sessions in New Orleans in November 2025. A news summary of it was re-released in late August 2026 and picked up widely. The findings have not changed, and as of this writing the full study has not been published in a peer-reviewed journal.

References

1. Nnadi, Ekenedilichukwu, et al. “Effect of Long-Term Melatonin Supplementation on Incidence of Heart Failure in Patients with Insomnia.” Abstract MP2306, American Heart Association Scientific Sessions 2025, New Orleans, November 7-10, 2025.

2. American Heart Association. “Long-Term Use of Melatonin Supplements to Support Sleep May Have Negative Health Effects.” News release, November 3, 2025.

3. Science Media Centre. “Expert Reaction to Conference Abstract on Association Between Long-Term Melatonin Supplementation and Incidence of Heart Failure in Patients with Insomnia.” November 3, 2025.

4. Laugsand, Lars E., Linn B. Strand, Carl Platou, Lars J. Vatten, and Imre Janszky. “Insomnia and the Risk of Incident Heart Failure: A Population Study.” European Heart Journal 35, no. 21 (2014): 1382-1393.

5. St-Onge, Marie-Pierre, et al. “Multidimensional Sleep Health: Definitions and Implications for Cardiometabolic Health: A Scientific Statement from the American Heart Association.” Circulation (2025).

6. Cohen, Pieter A., Bharathi Avula, Yan-Hong Wang, Ikhlas Khan, and Roy Gerona. “Quantity of Melatonin and CBD in Melatonin Gummies Sold in the US.” JAMA 329, no. 16 (2023): 1401-1402.

7. Li, Jingen, Virend K. Somers, Naima Covassin, et al. “Trends in Use of Melatonin Supplements Among US Adults, 1999-2018.” JAMA 327, no. 5 (2022): 483-485.

8. Sateia, Michael J., Daniel J. Buysse, Andrew D. Krystal, David N. Neubauer, and Jonathan L. Heald. “Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline.” Journal of Clinical Sleep Medicine 13, no. 2 (2017): 307-349.

9. Edinger, Jack D., J. Todd Arnedt, Suzanne M. Bertisch, et al. “Behavioral and Psychological Treatments for Chronic Insomnia Disorder in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline.” Journal of Clinical Sleep Medicine 17, no. 2 (2021): 255-262.

10. Grossman, Ehud, Moshe Laudon, and Nava Zisapel. “Effect of Melatonin on Nocturnal Blood Pressure: Meta-Analysis of Randomized Controlled Trials.” Vascular Health and Risk Management 7 (2011): 577-584.

11. Hoseini, Seyedeh Ghazaleh, Mohammad Heshmat-Ghahdarijani, Kiyan Heshmat-Ghahdarijani, et al. “Melatonin Supplementation Improves N-Terminal Pro-B-Type Natriuretic Peptide Levels and Quality of Life in Patients with Heart Failure with Reduced Ejection Fraction: Results from MeHR Trial.” Clinical Cardiology 45, no. 4 (2022): 417-426.

Published on damianrasch.com. The above information was composed by Dr. Damian Rasch, drawing on individual insight and bolstered by digital research and writing assistance. The information is for educational purposes only and does not constitute medical advice.