PSA that melatonin use was way out of control before this study was even published.
Sleep aid melatonin is shipped in pills containing ridiculous amounts of the stuff—I’ve seen 10, 12, and 20mg myself, Amazon has a 40mg fast dissolve and 60mg gummies.
This spikes your blood amount with 100x-1000x of your natural cycle of melatonin. Why? Because melatonin is not, repeat not, the signaling molecule that makes you sleepy. It responds to light levels and triggers the cascade of other molecules that make you sleepy, several hours after it peaks. So that's why the 100x overdose—you are trying to kick those secondary mechanisms into overdrive, “hey everyone it is black as the abyss of hell I guess we gotta sleep!!”, because Americans taking melatonin want to pop one just before bed and have it knock them out.
And it does that for like 2 or 3 days before your body starts down-regulating all of its sensitivities to those melatonin byproducts. Nerve cells like to be tickled, not zapped, when you shock them like this they react angrily.
You want to use melatonin to reinforce circadian rhythm and fight jet lag, you do it with amounts in the ~100 micrograms range, slow release if you can find it, and you take that at sunset and let it reinforce your normal cycle. If you're looking for an acute sleep aid, take a walk, get fresh air, drink water, and if those don't help pop a Benadryl/Unisom (it's the same drug either way). If you have doctor’s orders of course follow those, but if you're just trying to self-medicate that’s how you do it.
Absolutely unsurprising that punching your sleep apparatus in the gut once every day for five years increases some sort of stress on your heart.
In grad school I got to attend a talk by one of the researchers who was involved in the discovery of melatonin as a sleep aid for humans. He said that his team had hoped for it to become a prescription medicine dosed at 500 mcg, because anything higher gave paradoxical effects and actually made sleep worse. But it ended up being classified as a supplement in the US rather than a drug, so they had no way to control the dosage on the market.
The other useful thing I learned is that melatonin isn't primarily involved in falling asleep, its main function as a hormone is in staying asleep. I've started taking it sporadically if I wake up in the middle of the night, to make sure I get back to a deep sleep and stay there, and it seems to be super effective for this.
There was a collection of studies about a decade ago that seemed to determine the optimal use of Melatonin was about 350 micrograms taken about 1 hour before bed. The ideal was also slow release which was the best you could do to match the bodies process currently. The doses you can buy are far too high even the 1.5mg ones.
> you take that at sunset and let it reinforce your normal cycle
Yes, the way Michael Grandner explains it in this podcast[0], melatonin is an ancient molecule that signals, "it is dark." If you give it to nocturnal species, it wakes them up!
Are you sure about this? Everything I can find says Benadryl is diphenhydramine, and Unisom is doxylamine. (Both linked to increased dementia risk, for what it's worth.)
From streetlights everywhere, emergency vehicles blasting sirens at all hours, trains blasting horns (miles away but are still audible), its no surprise that Americans are struggling to sleep if this is your environment.
I know someone with a condition (I don't recall the name of it) but it actually calls for these massive doses of melatonin (up to 100 mg). The vast majority of people wanting to use it should start LOW- as in 0.25-0.5 mg.
Sleep experts say it is not possible to draw conclusions about melatonin from this study's findings — it did not prove cause and effect. A more likely explanation of the results is that insomnia itself could be to blame. In that case, melatonin would be an “innocent bystander”.
I have wondered if the first generation antihistamine dementia studies might have the same problem. People popping antihistamines for sleep probably have insomnia, which is already known to cause dementia.
This is a trash study and the title implying that this is an AHA statement is misleading. It was a data dredge associational study with minimal controlling for other covariates / risk factors for heart failure. The implication that melatonin has a causal relationship with CHF based on this alone is a pretty big jump.
I'd been taking 3mg slow release melatonin daily for years up until a few months ago. To be honest, I'm not sure it has any significant effect.
Regular exercise and a consistent sleep routine (cardio, weight lifting, going to bed early, and waking up early) has been more effective for me.
According to my fitbit, my average sleep duration is 6hr 30min over the last 2 years, down from 7hr30. When I wake up, there's no going back.
The biggest contributor to my reduction in sleep is my job, which in the last few years added stack ranking and by-annual performance reviews which requires daily book keeping of my "company impact".
I also got an echo-cardiogram last week (unrelated) and it came back in top shape (have a calcium score test coming up). Not saying melatonin isn't a risk for cardio health, but as a male in his early 30s with a family history of heart disease, nothing seems to indicate an increase in damage in my case.
This is an abstract that hasn’t been peer-reviewed… based on prescription data for an over-the-counter medication. This will be horribly inaccurate because it will miss all the folks who just buy the medication on their own and never have it documented.
These TriNetX studies are usually garbage because they’re entirely dependent on how accurate/up-to-date the medical record is.
Yes, this should have been a pure dose-response study among people with any history of filled melatonin scripts.
The comparison between the US and UK probably leads to two issues - US users use way too much melatonin and swamp heart disease signal, while UK patients prescribed melatonin probably have significant sleep derangement (consider how much effort it takes to get prescribed something for sleep - you need to schedule an appointment, convince your doctor, go to the pharmacy, etc)
I was scrolling around to see if I can find someone else that thought the same.
In my usage of melatonin, it's only when I'm super stressed and can't seem to calm down enough to sleep.
There's a thing going on in Australia with Melatonin. It's not OTC, it's a prescription thing. BUT doctors typically just tell people to buy online from America because it's much cheaper. So the TGA(Therapeutic Goods Administration) did some testing of what you can get online from America:
and are now recommending not to buy online because the doses are completely unregulated. They even reached out to companies like iHerb and asked them not to sell to Australians.
So, whatever dose you think you're taking, assume it's a bit of a guesstimate...
I tried to make the title a little less hyperbolic than the article starts out, as it's not a published study and it's basically a huge meta analysis that has no other information on age range, dosage, other health problems, etc. But the implications are worth considering.
So if I workout every day, some days do strength training others long runs, cardio, sprints, strides my heart falure risk is higher with the usage of melatonin pills?
Also in the article it mentions that they focus only on groups that have already been prescribed the medication or have diagnosed insomnia or other heart related issues so if you are fully healthy and take it from time to time to recover sleep or change a timezone(when travelling) it might be okay for single time use(I am not a doctor).
It's very plausible that anxiety causes heart disease, anxiety causes insomnia, and insomnia leads people to use melatonin. Same with diphenhydramine, overactive inflammatory response causes allergies, allergic people take allergy meds, and too much inflammation contributes to dementia.
Association studies too easily get interpreted as X causes Y. Maybe that's true, but not necessarily.
Reading the comments here: why does every society on this planet produce a group of people that just try to medicate every little inconvenience away without regard for their bodies? It is horrifying. I suppose it is for emotional comfort?
This study is garbage and I suspect it exists to help justify making melatonin a controlled substance so phrama can push their prescription sleep aides.
i tried to deal with sleeplessness by using multiple 5mg melatonin pills per night and it did nothing and made me fell gross. then my doctor said to cut 3 mg pills in half, and 1.5 mg worked far better than over-dosing myself! but he didn't tell me it was bad for me, but only i was taking TOO much of it.
This study is just another case of confusing correlation with causation, wrapped in a scary headline to grab attention.
The problem here is that they compared people who were already sick enough to need long-term melatonin prescriptions with those who weren’t. That’s not testing melatonin’s effects, it’s just showing that people with serious health problems (like chronic insomnia, depression, or anxiety) tend to have worse outcomes. And surprise, those same conditions are already known to increase heart risks.
Here’s the kicker: in the US, melatonin is over-the-counter. So their "non-melatonin" group probably included plenty of people using it anyway (they just didn’t have a prescription on record).
No info on doses, no explanation of how it might actually cause heart issues, and it’s not even peer-reviewed, it's just a conference abstract. Even the AHA expert they quoted sounds pretty skeptical (but of course, the press release still makes it sound like melatonin is the villain).
Honestly, if you wanted to design a study that would produce misleading results, you’d do exactly this: use observational data, ignore selection bias, and skip adjusting for how severe people’s conditions were. The real takeaway is that people with chronic insomnia have worse health. Groundbreaking stuff (not), applause.
I mentioned this study to my wife and she immediately shot back “it’s a garbage study that doesn’t control for anything in particular sleep apnea which is correlated with elevated risk of heart attacks.”
It's just important to remember that melatonin, like most all dietary supplements sold in the U.S. is severly under studied. Melatonin is allowed to be sold because it exists in nature, not because it has been proven safe. This is essentially true of anything sold as a dietary supplement.
Having said that, it doesn't necessarily make it dangerous. But, like myself and others have said in this post, please do take your dosage into consideration, as well as whether you're using it on a daily basis, as there are other things that could be preventing you from falling asleep/staying asleep that may be better addressed by a doctor, such as sleep apnea, as you mentioned.
[+] [-] crdrost|4 months ago|reply
Sleep aid melatonin is shipped in pills containing ridiculous amounts of the stuff—I’ve seen 10, 12, and 20mg myself, Amazon has a 40mg fast dissolve and 60mg gummies.
This spikes your blood amount with 100x-1000x of your natural cycle of melatonin. Why? Because melatonin is not, repeat not, the signaling molecule that makes you sleepy. It responds to light levels and triggers the cascade of other molecules that make you sleepy, several hours after it peaks. So that's why the 100x overdose—you are trying to kick those secondary mechanisms into overdrive, “hey everyone it is black as the abyss of hell I guess we gotta sleep!!”, because Americans taking melatonin want to pop one just before bed and have it knock them out.
And it does that for like 2 or 3 days before your body starts down-regulating all of its sensitivities to those melatonin byproducts. Nerve cells like to be tickled, not zapped, when you shock them like this they react angrily.
You want to use melatonin to reinforce circadian rhythm and fight jet lag, you do it with amounts in the ~100 micrograms range, slow release if you can find it, and you take that at sunset and let it reinforce your normal cycle. If you're looking for an acute sleep aid, take a walk, get fresh air, drink water, and if those don't help pop a Benadryl/Unisom (it's the same drug either way). If you have doctor’s orders of course follow those, but if you're just trying to self-medicate that’s how you do it.
Absolutely unsurprising that punching your sleep apparatus in the gut once every day for five years increases some sort of stress on your heart.
[+] [-] canjobear|4 months ago|reply
The other useful thing I learned is that melatonin isn't primarily involved in falling asleep, its main function as a hormone is in staying asleep. I've started taking it sporadically if I wake up in the middle of the night, to make sure I get back to a deep sleep and stay there, and it seems to be super effective for this.
[+] [-] PaulKeeble|4 months ago|reply
[+] [-] getpost|4 months ago|reply
Yes, the way Michael Grandner explains it in this podcast[0], melatonin is an ancient molecule that signals, "it is dark." If you give it to nocturnal species, it wakes them up!
[0] https://www.youtube.com/watch?v=AQF_eopP1ys
[+] [-] eurleif|4 months ago|reply
Are you sure about this? Everything I can find says Benadryl is diphenhydramine, and Unisom is doxylamine. (Both linked to increased dementia risk, for what it's worth.)
[+] [-] pedalpete|4 months ago|reply
I also thought this was the case, but everything I've seen suggests that taking melatonin does not alter the natural production of melatonin.
You are correct about everything else though.
[+] [-] happymellon|4 months ago|reply
From streetlights everywhere, emergency vehicles blasting sirens at all hours, trains blasting horns (miles away but are still audible), its no surprise that Americans are struggling to sleep if this is your environment.
Melatonin isn't going to fix that.
[+] [-] nerdsniper|4 months ago|reply
[+] [-] temp0826|4 months ago|reply
[+] [-] DANmode|4 months ago|reply
After 1-3mg, you’re doing yourself a disservice.
At least, for sleep purposes. I cannot comment on its use as an antioxidant.
[+] [-] lateforwork|4 months ago|reply
Source: https://www.nytimes.com/2025/11/05/well/melatonin-heart-heal...
[+] [-] api|4 months ago|reply
[+] [-] GoodOldNe|4 months ago|reply
[+] [-] klipklop|4 months ago|reply
[+] [-] apatheticonion|4 months ago|reply
Regular exercise and a consistent sleep routine (cardio, weight lifting, going to bed early, and waking up early) has been more effective for me.
According to my fitbit, my average sleep duration is 6hr 30min over the last 2 years, down from 7hr30. When I wake up, there's no going back.
The biggest contributor to my reduction in sleep is my job, which in the last few years added stack ranking and by-annual performance reviews which requires daily book keeping of my "company impact".
I also got an echo-cardiogram last week (unrelated) and it came back in top shape (have a calcium score test coming up). Not saying melatonin isn't a risk for cardio health, but as a male in his early 30s with a family history of heart disease, nothing seems to indicate an increase in damage in my case.
[+] [-] Smileyferret|4 months ago|reply
These TriNetX studies are usually garbage because they’re entirely dependent on how accurate/up-to-date the medical record is.
[+] [-] bonsai_spool|4 months ago|reply
The comparison between the US and UK probably leads to two issues - US users use way too much melatonin and swamp heart disease signal, while UK patients prescribed melatonin probably have significant sleep derangement (consider how much effort it takes to get prescribed something for sleep - you need to schedule an appointment, convince your doctor, go to the pharmacy, etc)
[+] [-] bilsbie|4 months ago|reply
[+] [-] ajma|4 months ago|reply
[+] [-] Andaith|4 months ago|reply
https://www.abc.net.au/news/2025-09-29/tga-safety-concerns-o...
and are now recommending not to buy online because the doses are completely unregulated. They even reached out to companies like iHerb and asked them not to sell to Australians.
So, whatever dose you think you're taking, assume it's a bit of a guesstimate...
[+] [-] pogue|4 months ago|reply
[+] [-] cultofmetatron|4 months ago|reply
[+] [-] HL33tibCe7|4 months ago|reply
[deleted]
[+] [-] jumperabg|4 months ago|reply
Also in the article it mentions that they focus only on groups that have already been prescribed the medication or have diagnosed insomnia or other heart related issues so if you are fully healthy and take it from time to time to recover sleep or change a timezone(when travelling) it might be okay for single time use(I am not a doctor).
[+] [-] cbare|4 months ago|reply
Association studies too easily get interpreted as X causes Y. Maybe that's true, but not necessarily.
[+] [-] hollerith|4 months ago|reply
[+] [-] Kalanos|4 months ago|reply
[+] [-] rf15|4 months ago|reply
[+] [-] naruhodo|4 months ago|reply
[+] [-] garciasn|4 months ago|reply
[+] [-] klipklop|4 months ago|reply
[+] [-] skopje|4 months ago|reply
[+] [-] protocolture|4 months ago|reply
[+] [-] xchip|4 months ago|reply
[+] [-] almosthere|4 months ago|reply
[+] [-] recurseP|4 months ago|reply
The problem here is that they compared people who were already sick enough to need long-term melatonin prescriptions with those who weren’t. That’s not testing melatonin’s effects, it’s just showing that people with serious health problems (like chronic insomnia, depression, or anxiety) tend to have worse outcomes. And surprise, those same conditions are already known to increase heart risks.
Here’s the kicker: in the US, melatonin is over-the-counter. So their "non-melatonin" group probably included plenty of people using it anyway (they just didn’t have a prescription on record).
No info on doses, no explanation of how it might actually cause heart issues, and it’s not even peer-reviewed, it's just a conference abstract. Even the AHA expert they quoted sounds pretty skeptical (but of course, the press release still makes it sound like melatonin is the villain).
Honestly, if you wanted to design a study that would produce misleading results, you’d do exactly this: use observational data, ignore selection bias, and skip adjusting for how severe people’s conditions were. The real takeaway is that people with chronic insomnia have worse health. Groundbreaking stuff (not), applause.
[+] [-] rayiner|4 months ago|reply
[+] [-] astrange|4 months ago|reply
You should instead design the study so it doesn't need massaging afterwards.
[+] [-] pogue|4 months ago|reply
Having said that, it doesn't necessarily make it dangerous. But, like myself and others have said in this post, please do take your dosage into consideration, as well as whether you're using it on a daily basis, as there are other things that could be preventing you from falling asleep/staying asleep that may be better addressed by a doctor, such as sleep apnea, as you mentioned.