Long-term use of melatonin supplements to support sleep may have negative heart health effects

Medical Xpress / American Heart Association's Scientific Sessions 2025 ^ | Nov. 3, 2025

[ConservativeMind]

Long-term use of melatonin supplements, often used to promote sleep and address insomnia, is associated with a higher risk of heart failure diagnosis, heart failure, hospitalization and death from any cause in chronic insomnia, according to a preliminary study.

Melatonin is a hormone naturally produced in the body by the pineal gland, and it helps regulate the body's sleep-wake cycle. Melatonin levels increase during darkness and decrease during daylight. Chemically identical synthetic versions of the hormone are often used.

The supplements are widely available over the counter in many countries, including the U.S. In the U.S., over-the-counter supplements are not regulated, so each brand of supplement can vary in strength, purity, etc.

In this study, researchers classified people who had used melatonin long-term (with long-term use defined as a year or more documented in their electronic health records) as part of the "melatonin group."

In contrast, those who never had melatonin recorded anywhere in their medical records were classified as the "non-melatonin group."

The main analysis found:

—Among adults with insomnia, those whose electronic health records indicated long-term melatonin use (12 months or more) had about a 90% higher chance of incident heart failure over five years compared with matched non-users (4.6% vs. 2.7%, respectively).

—There was a similar result (82% higher) when researchers analyzed people who had at least two melatonin prescriptions filled at least 90 days apart. (Melatonin is only available by prescription in the United Kingdom.)

A secondary analysis found:

—Participants taking melatonin were nearly 3.5 times as likely to be hospitalized for heart failure when compared to those not taking melatonin (19.0% vs. 6.6%, respectively).

—Participants in the melatonin group were nearly twice as likely to die from any cause than those in the non-melatonin group (7.8% vs. 4.3%, respectively) over the five-year period.

[SkyDancer]

At what MG dose? Goes from 1mg to 10mg per pill.

[jimwatx]

Yikes I’ve been taking higher than average doses of it just about every night for probably over a decade.

[KittyKares]

I can’t believe how man magnesiums there are! I have a pill with 7 forms of magnesium, not one being glycinate.

[jimtorr]

I have been taking Melatonin for several years. I asked my cardiologist about it before I started, and he has no problems with it.

[frank ballenger]

“Relaxium Sleep Aid contains melatonin. It is a key ingredient in the supplement, along with other sleep-promoting substances such as magnesium, ashwagandha, and tryptophan.”

And I trusted Mike Huckabee and Bill O’Reilly. /S

[frank ballenger]

RE: I asked my cardiologist about it before I started, and he has no problems with it.

But the doctor laughed to himself “I have no problems with it because I’m not the guy taking the stuff.”

[Magic Fingers]

“Yikes I’ve been taking higher than average doses of it just about every night for probably over a decade.”

I’ve been taking it at least that long, but only 0.25 mg (sublingually). I read that 0.3 mg/day is the amount that a young (which I’m not) person’s healthy body produces naturally, so I guessed that a supplement of approximately that amount wouldn’t cause (much/any) harm.

[kruss3]

RUSSEL REITER PHD AT UT SAN ANTOINIO IS THE WORLD RECOGNIZED EXPERT ON MELATONIN WITH ABOUT 1200 PUBLICATIONS. HE TAKES 40 MILLIGRAMS OF MELATONIN DAILY. HE IS ABOUT 90 YEARS OLD A GOING STRONG. https://www.google.com/search?q=RUSSEL+REITER+UTSA+MELATONIN&oq=RUSSEL+REITER+UTSA+MELATONIN&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIHCAEQIRigATIHCAIQIRigATIHCAMQIRigATIHCAQQIRigATIHCAUQIRiPAtIBCjEzNDY4ajBqMTWoAgiwAgHxBSUNmyZK4ide8QUlDZsmSuInXg&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:820f7199,vid:XI_YFoBWlgE,st:0

[ProtectOurFreedom]

Wow, not good. My doc recommended melatonin many years ago to help with sleep. I was taking 5 mg highly for quite a few years but, after using it a long while, I think it actually contributed to poorer sleep quality and stopped it maybe 6 to 12 months ago. I think my sleep quality (such as it is) improved after discontinuing it.

I wonder if the damage is permanent.

I have no idea now many years I took it.

[Prince of Space]

I just started taking that, so thanks for the info. Maybe I can wean off melatonin now.

[ckilmer]

I have taken melatonin off and on for 2-3 decades.

Usually the dose makes the poison.

They did not say what the dosages were.

[Diana in Wisconsin]

I can’t take the stuff. It gives me nightmares. Really, REALLY scary dreams.

Beau has been using it; he says no scary dreams, but his dreams are much more vivid than they normally are.

I will mention this to him as his Mom and both Grandfathers died of quick and unexpected heart attacks.

Thanks! :)

[aimhigh]

Correlation or causation?

Has to be correlation, unless they can connect dosage to the death rate. Sleep Apnea leads to the same mortality results. I'd love to know how many of these trial participants took melatonin instead of treating their apnea with a Cpap.

[Pete from Shawnee Mission]

Diana....Some human melatonin supplements are sourced from animal pineal glands. Could be the problem? Or low quality brands or contamination with something?>

Other things that are supposed to help with sleep. Glycine magnesium and GABA.

foods:

https://www.goodrx.com/melatonin/foods-melatonin

Interestingly, Melatonin can act as an antioxident.

"The MOST POWERFUL Antioxidant Is Melatonin, NOT Glutathione -"

"Melatonin is uniquely effective in protecting mitochondria, the primary source of cellular ROS. It accumulates in mitochondria, where it improves electron transport chain efficiency, reduces electron leakage, maintains membrane potential, and prevents mitochondrial permeability transition, thereby reducing radical formation and protecting against mitochondrial dysfunction. This mitochondrial targeting makes melatonin a highly effective antioxidant in conditions involving ischemia-reperfusion injury, such as stroke and heart attack. Its antioxidant effects have been demonstrated in various disease models, including cancer, diabetes, neurodegenerative disorders, cardiovascular disease, liver and kidney diseases, and infertility."

Which makes it odd that they would try to associate it with heart attacks.

[Veto!]

I read this somewhere else about ten days ago days ago and threw out my bottle of liquid melatonin. I do use a homeopathic remedy called “Sleep” that I buy on AMZ :Health stores and even some drug stores carry them.

“Bioron SleepCalm Meltway Tablets. “
You take one or two and let them melt under your tongue. They contain a little sugar so I use them before I brush my teeth. I’m a very small person, and I take two.

Also, I sometimes take “Valerian”, calming and relaxing liquid drops. Really helped on a four-day trip last week. A little pricey but if it works for you it’s worth it.

[Veto!]

I have Magnesium Glycinate and it doesn’t help at all.
I think it’s a “different strokes for different folks” kind of thing.

[Diana in Wisconsin]

I’ll have him look into it when he gets back. He’s gone a-field again, LOL! He always sleeps well when he’s living in the middle of the woods somewhere. Go figure! ;)

[Mozzafiato]

This is the one I take...one or two tablets depending on how deep of a sleep I want. It does give me extremely vivid and detailed dreams, though, which can be a little unnerving at times. Probably does affect people differently, as you said.

[Veto!]

NOW is a good brand. Glad this works for you.

[Veto!]

I do take liquid calcium/magnwaium beforer bed too, buy at Natural Grocer in my ‘hood. But it’s not enough to turn off my busy mind and put me to sleep by itself. I actually take it for bone strength, have broken a few . Osteoporosis.

Anyway, we both take natural products instead of drugs, which is good.