American Heart Association Says Melatonin May Be Linked to Serious Heart Risks

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.

These TriNetX studies are usually garbage because they’re entirely dependent on how accurate/up-to-date the medical record is.

Source: https://www.nytimes.com/2025/11/05/well/melatonin-heart-heal...

Association studies too easily get interpreted as X causes Y. Maybe that's true, but not necessarily.

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...

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.

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.

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).

I've never met a pill popper that got up earpy for a run, had a solid active day routine and went offline after 7pm. Their solution is to remain sedentary and take a drug. No wonder their hearts are messed up.