Is taking melatonin every night bad for your heart?
Maybe. In this study of 130,828 adults with insomnia, people who took melatonin for more than a year had about a 90% higher risk of developing heart failure over five years compared with similar people who did not use it.
Melatonin is one of the most popular sleep aids in the world. Millions of people take it nightly, and most assume it is completely safe because it is a hormone the body already makes. This new research is the first big warning sign that long-term, heavy use might carry a hidden cost for the heart. The findings do not prove melatonin causes harm, but they are strong enough that doctors and nightly users should pay attention.
What the data show
Researchers looked at the medical records of 130,828 adults who had insomnia, with an average age of about 56. They compared people who took melatonin for more than a year against people with insomnia who did not use it. Over five years, the long-term melatonin group had roughly a 90% higher risk of developing heart failure, a condition where the heart cannot pump blood as well as it should.
The other numbers were even more striking. People in the long-term melatonin group were nearly 3.5 times as likely to be hospitalized for heart failure. They were also almost twice as likely to die from any cause during the study period. These are large differences, and they held up across a very big group of patients, which makes them hard to ignore.
Dr. Kumar’s Take
I want to be honest about what this study can and cannot tell us. It is an observational analysis, which means the researchers watched what happened in real patient records. They did not assign people to take melatonin or not. So we cannot say melatonin caused these heart problems. It is possible that people who reach for melatonin night after night have worse underlying health to begin with, and that worse health is what drives the heart failure.
That said, the size of the effect surprised me. A near doubling of heart failure risk is not a small blip. For a supplement that most people treat like candy, that deserves a serious second look. I am not telling my patients to panic, but I am telling them that “natural” does not mean “free of consequences.”
Why this matters
Most people think of melatonin as harmless because the body makes it on its own. But the doses in supplements are often far higher than what your body produces naturally. Taking a strong dose every single night for years is very different from your brain releasing a tiny amount at bedtime. This study is a reminder that we have surprisingly little long-term safety data on a product sold on every pharmacy shelf.
Heart failure also rarely appears out of nowhere. It usually builds slowly as the heart is strained over time. If melatonin plays even a small role in that process, the people most at risk would be exactly the ones taking it for years, which is the group this study flagged.
Important limitations
The biggest limitation is that this research cannot prove cause and effect. Insomnia itself is tied to heart problems, since poor sleep raises blood pressure and stress on the body. People with the worst insomnia may both use more melatonin and face higher heart risk for reasons that have nothing to do with the supplement. The study also relied on medical records, which may not capture exactly how much melatonin each person took or whether they used other sleep aids. These findings should be seen as a red flag worth studying, not a final verdict.
Practical Takeaways
- If you take melatonin nightly, treat it as a short-term tool rather than a forever habit, and talk with your doctor about how long you really need it.
- Use the lowest dose that helps you sleep, since many people get the same benefit from 0.5 to 1 milligram as from the much larger 5 or 10 milligram pills.
- If you have heart disease, high blood pressure, or a family history of heart failure, mention your melatonin use at your next checkup so your doctor can weigh the risks.
- Work on the root causes of poor sleep, such as a consistent bedtime, less screen time at night, and limiting caffeine and alcohol, before relying on a pill long-term.
Related Studies and Research
- Insomnia plus sleep apnea raises heart disease risk nearly 4-fold
- What 50 years of fibrate research tells us about heart risk
- PPIs cause low magnesium: meta-analysis reveals 43% higher risk
- Does cholesterol really cause atherosclerosis? A study from 1961 raises questions
FAQs
How much melatonin is safe to take each night?
There is no official long-term safety dose, which is part of the problem this study highlights. Most sleep experts suggest starting with a low dose between 0.5 and 1 milligram taken about an hour before bed. Many over-the-counter pills contain 5 to 10 milligrams, which is far more than your body would ever release on its own. If you find yourself needing melatonin every night for months, that is a sign to see your doctor rather than simply increasing the dose.
Does insomnia by itself increase heart failure risk?
Yes, poor sleep is independently linked to heart trouble. When you do not sleep well, your blood pressure stays higher, stress hormones rise, and your heart gets less recovery time overnight. This is one reason the melatonin findings are hard to untangle, since the people taking it already had insomnia and its heart risks. Treating the underlying cause of sleeplessness may protect your heart more than any pill.
Should I stop taking melatonin after reading this study?
Not necessarily, and you should not make sudden changes based on one observational study. The research raises a real safety question, but it cannot prove melatonin caused the heart problems it found. The smarter move is to review your use with your doctor, especially if you have taken it nightly for a year or more or already have heart risk factors. For occasional use to fix jet lag or a few bad nights, the concern is much smaller.
Bottom Line
This large study found that adults with insomnia who used melatonin for more than a year had about a 90% higher risk of heart failure, were nearly 3.5 times more likely to be hospitalized for it, and were almost twice as likely to die during the five-year period. The findings are associational and do not prove melatonin is the cause. Still, they puncture the common belief that a nightly melatonin pill is automatically harmless. If you rely on it long-term, the safest path is the lowest effective dose, a hard look at why you cannot sleep, and an honest conversation with your doctor.
