Melatonin and Heart Health: Don’t Let the Headlines Fool You
- Rebecca Montrone
- Nov 9, 2025
- 3 min read
by Rebecca Roentsch Montrone, BS - Wondrous Roots, Inc.
You may have seen recent headlines claiming that long-term melatonin use increases the risk of heart failure. Naturally, that catches people’s attention—especially those of us who take melatonin regularly or recommend it for sleep, antioxidant support, or even as part of broader wellness or anticancer protocols.
So let’s unpack what this study actually said—and what it didn’t.
What the Latest Study on Melatonin and Heart Health Really Means
Researchers analyzed medical records from over 130,000 adults diagnosed with insomnia. They found that people who took melatonin for a year or more were more likely to develop heart failure within five years than those who didn’t take it.
That sounds worrisome until you look closer. The difference was 4.6% versus 2.7%—a relative 90% increase, but an absolute difference of less than 2%. Melatonin users were also more likely to be hospitalized for heart failure and had a slightly higher death rate over the study period.
These results were presented at the 2025 American Heart Association conference as observational data—meaning researchers could identify correlations, but not causes.
Why This Doesn’t Prove Melatonin Causes Heart Problems
Observational studies are valuable for spotting trends, but they can’t determine cause and effect. In this case, the most logical explanation is that chronic insomnia itself—not melatonin—is the real culprit.
Making a causal correlation between melatonin use and heart failure from a study like this is like blaming umbrellas for the rain—they may show up at the same time, but one doesn’t cause the other.
People who need melatonin every night tend to have more persistent or severe insomnia, which is already linked to:
Increased inflammation and oxidative stress
Higher nighttime blood pressure and cortisol
Reduced heart rate variability and overall cardiovascular resilience
In other words, melatonin users may simply represent a higher-risk group because of their underlying sleep disorder—not because of the supplement they’re using to manage it.
Other Important Factors
Product inconsistency: Studies show melatonin supplements can vary wildly in content—from 80% less to nearly five times the amount listed on the label. Some even contain serotonin contamination. So, if there were a connection, it could just as easily point to unregulated supplement quality, not melatonin itself.
Dose matters—but not the way the headlines imply: Many media reports insist on “low-dose only” melatonin, but there is no established upper toxicity limit. In fact, higher doses have been used safely in studies for neuroprotection, mitochondrial support, and even cancer therapy.
Insomnia is a cardiovascular risk condition. Untreated chronic sleep disruption increases heart failure risk whether or not melatonin is involved. Addressing the root cause—sleep apnea, stress, medication side effects, circadian disruption—is far more important than blaming melatonin.
What We Actually Know About Melatonin
Melatonin is far more than a sleep hormone. It is a powerful antioxidant and mitochondrial protector, involved in regulating inflammation, blood pressure, and cellular energy. Research has shown it can:
Reduce oxidative damage to heart tissue
Support healthy cardiac remodeling after injury
Improve mitochondrial function and metabolic balance
Protect against neurodegeneration and even aid cancer therapy
These effects are generally beneficial to the heart, not harmful.
The Bottom Line
The new study doesn’t show that melatonin causes heart failure—it shows that people with chronic, untreated insomnia are at greater cardiovascular risk, and many of those people happen to take melatonin.
If you use melatonin:
Choose a reliable, third-party tested brand to ensure accurate dosing.
Use it intentionally—at a dose appropriate for your goal, whether circadian support or higher-dose therapeutic use.
Remember that quality sleep hygiene, stress reduction, and identifying underlying causes of insomnia are just as essential.
The truth is, the relationship between melatonin and heart health is far more complex—and far more positive—than these headlines suggest.
Melatonin remains one of the most versatile and well-tolerated tools we have—especially when used wisely and in context. The real takeaway isn’t that melatonin is dangerous; it’s that we should never let a headline replace a full understanding of the science.
Key Takeaway
Don’t panic about the latest melatonin scare. The study shows a connection—but not causation—and most likely reflects the health risks of chronic insomnia, not of melatonin itself.
For much more information on melatonin and melatonin supplementation and health, please see my page:
