For years, melatonin has been seen as a safe, natural sleep aid—available over the counter and widely used by millions of Americans struggling to fall asleep. But new research is raising questions about whether long-term melatonin use might come with unintended heart risks.
A study presented this month at the American Heart Association’s Scientific Sessions suggests that adults who regularly took melatonin supplements for more than a year had a significantly higher chance of developing heart failure compared with those who didn’t use it. The findings, though preliminary, have experts urging caution—especially among people who rely on nightly melatonin to get rest.
The surprising new findings on melatonin and heart health
According to data shared by researchers at the AHA conference, people who used melatonin regularly over the long term were about 90% more likely to experience heart failure than nonusers. They also appeared more likely to be hospitalized or die from cardiovascular causes during the study period.
The analysis looked at more than 160,000 adults tracked through the UK Biobank database, one of the largest ongoing health studies in the world. The average age of participants was around 56, and slightly more than half were women.
Lead investigator Dr. Aneil Kumar, of the Cleveland Clinic Foundation, emphasized that while the study uncovered an association between melatonin use and increased heart risk, it does not prove cause and effect. Still, the results caught attention because melatonin use has surged in the past decade, particularly among middle-aged adults and seniors.
What the research actually shows
Melatonin is a hormone naturally produced by the brain to regulate sleep and wake cycles. Synthetic melatonin supplements are often marketed as a safe, non-habit-forming way to reset the body’s internal clock—helpful for jet lag, shift work, or occasional sleeplessness.
But the new findings suggest that using it chronically, especially at high doses, may not be harmless. The AHA researchers found:
- Long-term melatonin users (more than one year) had a 90% higher risk of heart failure.
- Users were more likely to be hospitalized for cardiovascular conditions.
- The link remained even after adjusting for age, sex, smoking, blood pressure, and diabetes.
Because the study relied on health records and prescription data, it cannot confirm how much melatonin each participant actually took or whether over-the-counter supplements played a role. Still, experts say the results should prompt a closer look at how this “natural” hormone may affect the heart.
How experts interpret the results
Melatonin is often viewed as benign, but that perception may not always be accurate. The supplement can affect the body’s circadian rhythm, which also regulates blood pressure, heart rate, and metabolism.
According to the Mayo Clinic, melatonin can interact with certain medications—including blood thinners, diabetes drugs, and blood pressure medications—and may cause side effects such as dizziness, daytime drowsiness, or short-term confusion in some users.
However, experts caution against panic. Dr. Kumar and others stress that the new study is observational—it shows a correlation, not proof that melatonin directly causes heart failure. More controlled research is needed before drawing firm conclusions.
“It’s a flag, not a final verdict,” says Dr. Kumar. “The key message is that melatonin isn’t completely risk-free, especially when used for long periods or at higher doses.”
What this means for people who take melatonin
If you take melatonin occasionally—say, to recover from jet lag or to get back on a regular sleep schedule—the available evidence suggests that’s generally safe for most adults.
But if melatonin has become part of your nightly routine, it may be time to pause and talk to your healthcare provider, especially if you:
- Have existing heart disease or a family history of it
- Take blood pressure, diabetes, or heart medications
- Experience unexplained fatigue, shortness of breath, or swelling
- Have been using melatonin for more than 12 months
“Natural” doesn’t automatically mean safe, especially when taken long-term or in high doses. Most supplements in the U.S. are not tightly regulated, meaning melatonin labels may contain more (or less) of the hormone than stated.
Safer, smarter ways to get better sleep
The good news: many proven, non-drug strategies can improve sleep naturally—without potential side effects or heart risk.
Experts recommend starting with sleep hygiene habits that strengthen your body’s natural rhythm:
- Go to bed and wake up at consistent times.
- Limit screens and bright light an hour before bedtime.
- Avoid caffeine, nicotine, and alcohol close to bedtime.
- Keep your bedroom cool, dark, and quiet.
- Try a relaxing routine—reading, stretching, or mindfulness.
If insomnia persists for more than a few weeks, cognitive behavioral therapy for insomnia (CBT-I) is considered the gold standard treatment. This structured approach, guided by a sleep-trained therapist, addresses the thoughts and habits that keep people awake—and it works as well as, or better than, medications for most people.
Short-term melatonin may still have a role for jet lag, shift work, or circadian rhythm disorders. But experts recommend starting with the lowest possible dose (0.5–1 mg) and using it only as needed.
The bottom line
The new research doesn’t mean everyone should stop taking melatonin immediately—but it’s a timely reminder to use it thoughtfully. While the supplement can be helpful for short-term sleep issues, long-term nightly use could carry risks that are only now coming to light.
If you’ve been taking melatonin regularly for months or years, talk with your healthcare provider about the safest way to taper or explore other solutions.
Your heart—and your sleep—may both benefit from a more balanced, natural rhythm.
