[HN Gopher] American Heart Association says melatonin may be lin...
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American Heart Association says melatonin may be linked to serious
heart risks
Author : pogue
Score : 63 points
Date : 2025-11-09 17:40 UTC (5 hours ago)
(HTM) web link (www.sciencedaily.com)
(TXT) w3m dump (www.sciencedaily.com)
| pogue wrote:
| 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.
| cultofmetatron wrote:
| insomnia is also highly correlated with heart attack risk so
| there's that
| michaelcampbell wrote:
| This whole thing is akin to the "I'm just asking questions"
| crowd.
| bilsbie wrote:
| I'd guess it's just correlated with poor sleepers.
| crdrost wrote:
| 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.
| PaulKeeble wrote:
| 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.
| wincy wrote:
| I buy 300mcg for me and my kids, it's a fantastic sleep aid.
| Thanks to Scott Alexander talking about it.
| recurseP wrote:
| Just so you know, some doctors recommend being careful with
| melatonin for kids since it's a hormone and there's not a
| ton of research on long-term effects. They say it might
| disrupt sexual development during adolescence. Kids produce
| more melatonin naturally and it is though that a reduction
| in melatonin production during adolescence is actually what
| triggers pubertal development. Might be worth looking into
| a bit more before making it something regular.
| canjobear wrote:
| 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.
| BobbyTables2 wrote:
| I suspect each brand tries to put more to out-compete with
| other brands.
|
| People look at multivitamins and think "more is better".
| Unfortunately they are stuffed with ingredients that can't be
| absorbed well together, but do result in higher sales...
| nerdsniper wrote:
| https://slatestarcodex.com/2018/07/10/melatonin-much-more-th...
| eurleif wrote:
| >Benadryl/Unisom (it's the same drug either way)
|
| 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.)
| grimpy wrote:
| There are two kinds of Unisom: diphenhydramine and doxylamine
| succinate.
| pogue wrote:
| They're both first generation antihistamines and work as
| agonists on the H1 receptor, causing sedation. There's no
| reason to choose one over the other for a first time user,
| but they can cause rapid tolerance. So, I'm guessing the
| only reason they offer both is if you'd become tolerant to
| one of them and can no longer fall asleep on it.
|
| https://en.wikipedia.org/wiki/H1_antagonist#First-
| generation...
| pogue wrote:
| Yes, I would use first generation antihistamines like those
| sparingly as they are anticholergenic. It's more of a long
| term concern rather than for occasional use.
|
| For the low dose melatonin, Life Extension brand sells
| patented MicroActive formula of fast release/slow release
| melatonin in a 1.5mg dosage and a 6 hour time released 300mcg
| version. It's a quality brand and those are the dosage ranges
| I would recommend sticking around.
|
| I have seen the insanely high 30mg+ amounts being sold and
| that's ridiculous. If you need that much, there's other
| factors going on. I would look into reducing caffeine intake,
| doing proper sleep hygiene (google it), and talk to a
| doctor/get a referral to a sleep specialist if it's an
| ongoing thing.
|
| But, also look into l-theanine, glycine/magnesium glycinate,
| valerian root extract, passionflower, lemon balm and things
| of that sort for occasional sleeplessness or trouble falling
| asleep. (Visit examine.com & ergo-log.com and search for
| these ingredients on there to see all the references, how
| they work, and for more info.)
|
| Natural isn't necessarily better, but I would recommend those
| any day over Z drugs, antihistamines and a lot of other rx
| sleep drugs. Make sure you're buying a quality brand though.
|
| Finally, please don't give melatonin to children...
|
| _Parents give kids more melatonin than ever, with unknown
| long-term effects_
| https://arstechnica.com/health/2025/04/melatonin-for-kids-
| sa...
| SoftTalker wrote:
| I'll never understand the desire of people to take pills
| for everything. There are _always_ side effects. If you
| have a medically diagnosed acute or chronic condition and
| there's not another option that's one thing. But if you can
| eat better, be more active, lose excess weight, etc that's
| what you should try to do.
| temp0826 wrote:
| 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.
| pedalpete wrote:
| Can you point to a source about the body down-regulating
| melatonin?
|
| 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.
| a2dam wrote:
| It doesn't. There's some minor evidence, but it's very
| quickly reversed.
| getpost wrote:
| > 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!
|
| [0] https://www.youtube.com/watch?v=AQF_eopP1ys
| almosthere wrote:
| probably written by a statin exec. There is no reason to trust
| anything anymore.
| Smileyferret wrote:
| 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.
| bonsai_spool wrote:
| 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)
| lateforwork wrote:
| 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".
|
| Source: https://www.nytimes.com/2025/11/05/well/melatonin-heart-
| heal...
| api wrote:
| 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.
| apatheticonion wrote:
| 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.
| skopje wrote:
| 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.
| recurseP wrote:
| 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.
| GoodOldNe wrote:
| 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.
| rayiner wrote:
| 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."
| protocolture wrote:
| Think Melatonin is Safe? Well this study is terrible and
| demonstrates nothing.
| cbare wrote:
| 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.
| hollerith wrote:
| But all anticholineric drugs seem to cause dementia in
| susceptible persons, not just anti-allergy ones.
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