Surprising Heart Results from This Huge Melatonin Study

So, one minute. The internet is ablaze with an alarming study linking melatonin to a sharp increase in the risk of heart failure. Now, a new study tells a completely different story. And this is why clickbait sucks. It just confuses everyone. Luckily though, when you go through the data, it actually all points in the same direction. And it gives us a clear picture regarding whether to take melatonin supplements or not. This is important because Americans now take melatonin at five times the rate that they did back in 1999. And a 2023 survey found that 64% of all adults have taken it at some point. That is tens of millions of people and plenty of short-term studies have shown benefits for sleep. But while melatonin supplements appear safe, long-term data has been lacking. And that's why the alarming 2025 study was so significant. It looked at 5 years of electronic health records to assess the effects of melatonin on a longer time horizon. And it found that long-term users had an, and get this, 89% higher risk of heart failure and were about 3. 5 times more likely to be hospitalized for it and over twice as likely to die from any cause. And that sort of data journalists love because it makes for wonderful clickbait titles. But if we take a careful look at the study, there were some big issues with the methodology behind it. The first had to do with the composition of the two groups that the researchers compared. So, what they're trying to do here is separate long-term melatonin users from those who don't use it. That's obviously foundational when it comes to answering their central question, which is about the safety of long-term use of melatonin. Now, when we look through the details of how the researchers established these two groups, we spot a key flaw. So, on one side were those with electronic health records that indicated a prescription for melatonin. That's the melatonin group. The non-melatonin group was made up of those whose health records did not mention melatonin. Now, here's the problem. The TREED X global research network database that the study relied on includes data from numerous countries. And in some countries, like the UK, patients require a prescription for melatonin, but in others like the US, they don't. Now, in this study, the melatonin group included just those whose records showed a prescription for melatonin. So, and this is the key point, anyone who was taking melatonin over the counter would end up in the non-melatonin group. Now, obviously, that's a huge problem. How can we draw any conclusions from the study if the non-melatonin group is consuming melatonin? The second major issue is

that this is an observational study. It's not a randomized control trial. So all that means is that it just tells us about association, not causation. And it's critical to remember that we can find all sorts of associations when we look at data sets, but not all of them can be explained by the underlying connection. So consider, for instance, the relationship between ice cream sales, and I've mentioned this a couple of times on the channel before, and shark attacks. So, guess what? They both peak in the summer. Now, you think about that for a moment. It's obvious why. And it isn't because ice cream is causing the attacks. Here's another interesting chart. Look at how closely autism diagnoses follow growth in organic food sales. Correlation, yes. Causal connection, surely not. But if we ignore these two issues from that 2025 study and assume that this association between heart failure and melatonin use is real, why might that be? And how would that impact our decision to use melatonin supplements? Well, here's a possibility. Maybe people with more severe insomnia are more likely to get a prescription for melatonin. And if that were true, then it would make sense of the pattern because we've got plenty of data showing that sleep disruption leads to worse heart related health problems. So, for instance, a 2024 meta analysis concluded that there's a strong causal connection between insomnia and the risk of heart disease. That would make sense since we know that a lack of sleep ramps up inflammation and inflammation is at the heart, pun intended, of many kinds of heart disease. So, it's not necessarily the melatonin that's causing the increase in heart failure. It might be instead the insomnia itself. And to really figure out what's going on, we need randomized controlled trials where one group takes the melatonin and we definitely know that the other group is not taking melatonin. They are just taking a placebo. And besides all of this, what we're looking at is just an abstract of a paper presented at a conference. It hasn't yet gone through the gauntlet of the peerreview process. All of that is preliminary. And even though this is a preliminary finding and there's a truckload of methodological issues, it got a truckload of press. Again, even though we've got studies at this point that point in the opposite

direction. So for instance, a 2025 meta analysis looked at melatonin use for those already diagnosed with heart failure and it combined four randomized control trials. So melatonin improved patient scores on measures of heart failure and it significantly boosted their quality of life. It also increased an important metric of blood vessel health. There was even a trend towards improvement in the heart's pumping ability, but this wasn't statistically significant. And this is consistent with an earlier analysis in 2022. It summarized the study evidence and it found that melatonin protected the heart in numerous human and animal studies. Still scary studies that grab headlines that can leave people feeling confused and in doubt. So overall, who is right here? Is melatonin dangerous for the heart or not? Well, a new study makes a

decisive contribution to this discussion. It's a meta analysis that includes 63 randomized control trials involving over 3,000 participants. This is a much more compelling kind of evidence than the study that raised the alarm bells last fall. So, not only are we dealing with randomized control trials instead of an observational study, but it's a meta analysis that combines data from large numbers of individual trials. So, it includes the best evidence available through to October 2025, just weeks before that heart failure study made all of those headlines. The focus of the study, though, isn't heart failure, and it doesn't speak to that directly. What it does give us is a wide-angle view of a set of factors that are highly relevant to heart health. They're also relevant to chronic conditions like type 2 diabetes and high blood pressure. Here's what they found when they ran the analysis. Melatonin supplements significantly reduced waist circumference, blood pressure, fasting blood glucose, LDL cholesterol, and total cholesterol. They also measured the effects of melatonin in another area, inflammation. And they found significant drops in several key markers of inflammation and oxidative stress. and melatonin use boosted antioxidant capacity in the blood. This is hugely significant since inflammation and oxidative stress have big impacts on heart disease and conditions like obesity and insulin resistance and the size of the effects here are generally modest but meaningful. The crucial thing to notice is that cumulatively they point decisively in the direction of an impact that supports heart health. Now I want to add an important caution here though. The trials included in this meta analysis, they were mostly short-term with many just lasting a few weeks. The longest was just over a year. So, this doesn't settle the question about the long-term effects of melatonin use. We still need long-term randomized control trials for that. But there's no question here that the evidence trends in a direction that looks positive. So, the most up-to-date study that we have today is encouraging. We don't see anything here that supports the alarming headlines from that heart failure study.

But there's another way to approach this issue, and that's to look at what melatonin actually does. Does it make sense that it would promote heart health or get in the way of heart health? Well, the first thing to understand is that melatonin is way more than just a sleep hormone. It's produced by the pineal gland in the brain, but it's also produced throughout the body, including the gut and the skin. It's a potent antioxidant and anti-inflammatory. It may also enhance the functioning of our blood vessels. And since blood vessel dysfunction and inflammation are central to heart disease, it makes sense that we can see these cardiovascular protective signals in that meta analysis that we looked at. And sleep itself is linked to heart health as I mentioned earlier. So melatonin's ability to improve sleep metrics likely has a multifaceted beneficial effect. So the benefits of melatonin supplements, they make sense in theory, and we've got some compelling study evidence about their effectiveness for better sleep along with suggestive evidence about their heart health. But as always, there are some things that we need to watch out for when moving from studies to actually how we approach supplementation. So the first is the matter of dosing. So melatonin supplements, they often contain very high doses, even over 5 milligs a day. And as I mentioned earlier, we don't have data on the long-term safety about this. So let me put that dose into perspective. The body produces between 10 to 80 micrograms of melatonin at night. And about 15% of melatonin in a supplement is absorbed by the body. So think about that 5 milligram dose. That would be 5,000 micrograms. And if 15% gets absorbed, that's about 750 micrograms. That's about 10 times the amount that our body naturally produces or more. So personally, I wouldn't take more than 1 millig of melatonin at night. In fact, I do take a melatonin regularly as part of my sleep supplement, but it includes just. 3 milligrams or 300 micrograms of melatonin. So, given the typical bioavailability, that dose sits in the middle of the range normally produced by the body. It's a mile away from the doses seen in some supplements. But just because I take a supplement does not in any way mean that you should as well. Second, we want to be careful about the product quality. So, a 2023 analysis of melatonin gummy products, for instance, found that the actual quantity of melatonin ranged from 74% to 347% of the amount specified on the label. Incredibly, one product didn't contain any detectable melatonin at all. So, it's a bit like playing gummy roulette. So, if you're shopping for a melatonin supplement, make sure you look for a good manufacturer and ideally a manufacturer that produces their certificates of analysis. And finally, the timing of melatonin supplementation is critical. So, it's important to remember how melatonin functions here. It isn't a seditive that just knocks you out. Rather, it's a hormone that plays a central role in regulating the body's natural sleepwake cycle. Melatonin works as a chronobiotic agent that can try and shift our sleepwake cycle. So, ideally, we want to be taking melatonin around 2 to 4 hours before we want to fall asleep. And when it comes to sleep supplements, melatonin does get all of the attention, but there is compelling evidence of another simple supplement that can have a positive impact on our sleep. So, make sure to check out this next video here to find out a recent study on its impact.