Should You Rethink Your Melatonin Habit?

A new study that links long-term melatonin use to a higher risk of heart failure has raised concern among sleep experts and those using the increasingly popular over-the-counter supplement. In light of those findings, doctors say it’s best to consult a sleep professional who can provide perspective and put the latest research in context — while also steering you toward an optimal solution for occasional or chronic insomnia.

“Melatonin is helpful for some specific situations, such as jet lag and delayed sleep-wake phase disorder,” says Carolyn D’Ambrosio, M.D., a pulmonologist with the University of Miami’s Health System who is also certified as a sleep medicine specialist.  “But we feel strongly that daily melatonin is not needed. Taking it is not completely benign.”

If further research determines that frequent and long-term use (about one year) of melatonin is, indeed, responsible for heart failure over time, that will signal a significant change in medical reasoning. Previous studies on its safety and effectiveness have been mixed, but many in the medical community have, until now, considered melatonin not only safe but potentially protective for cardiovascular health. Small clinical studies have pointed to its effectiveness in lowering nighttime blood pressure and reducing oxidative stress and inflammation.

Those cardio-protections, however, may be short-lived.

Melatonin is a hormone produced by the brain’s pineal gland; levels rise at night in response to darkness and drop during the day with exposure to light. It not only helps regulate the body’s sleep-wake cycle but is also believed to play a role in immune system regulation, blood pressure control, bone formation, and even reproductive function.

Studied in the 1960s and ’70s after a researcher isolated the chemical, melatonin was not marketed until the 1990s. By the turn of the century, however, usage had expanded rapidly, according to a National Institutes of Health (NIH) report. In fact, the use of melatonin supplements by U.S. adults more than quintupled between 1999 and 2018, from just 0.4% to 2.1% of adults. Sales spiked from $62 million in 2003 to over $800 million by 2020.

A more worrisome trend: up to 20% of kids under 14 are given melatonin, often nightly. While the prevalence of melatonin consumption in the past 30 days was significantly higher for school-aged children and preteens, almost 6% of preschool children were given melatonin by their parents, according to a 2023 article in JAMA Pediatrics. The frequency did not differ significantly across age groups, with melatonin administered from 1 to 7 days a week.

The supplement’s popularity is a direct result of both its commercial availability and the increase in sleep problems, driven mainly by the always-on modern lifestyle.

“People don’t always have good sleep habits,” says Dr. D’Ambrosio, who then goes on to list all the factors that can disturb our sleep: too much screen time, inconsistent schedules, daylight saving time, stress, caffeine, alcohol and lack of exercise.

What’s more, because melatonin is sold over the counter in the U.S., Australia, Japan, and most Asian and European countries require a prescription, many think “it’s a naturally occurring substance, so it must be OK to take.” That’s not true, according to Dr. D’Ambrosio. Side effects include daytime drowsiness, headache, vivid nightmares, and nausea.

The U.S. Food and Drug Administration does not regulate supplements.

So actual melatonin content can vary significantly from what is listed on the label, Dr. D’Ambrosio adds. Also, while experts recommend starting with a low dose (0.5 to 1 mg), the NIH report found that many individuals take doses above 5 mg nightly.

The new study, presented at the American Heart Association’s Scientific Sessions in November 2025, has not yet been peer-reviewed or published. It warns that long-term use (over 1 year) of melatonin supplements is linked to a 90% greater risk for heart failure, compared to non-users. Long-term users were also 3.5 times more likely to be hospitalized for heart failure and were nearly twice as likely to die from any cause during the study period.

Dr. D’Ambrosio is not surprised: “Cardiologists are now our number one referral source. Sleep and heart health are closely linked.” (Poor or insufficient sleep increases the risk of high blood pressure, stroke, and other cardiovascular problems.)

She says the new research in its current form is limited in its scope. More randomized controlled trials are needed to determine whether there is a direct causal link between melatonin and heart failure. If confirmed, this could likely lead to a change in how physicians recommend its usage — and maybe its easy availability.

Dr. D’Ambrosio suggests other methods to help improve sleep quality:

• Practice good sleep hygiene. Establish a consistent sleep schedule. Keep your bedroom dark, cool, and quiet. Limit your exposure to caffeine, alcohol and large meals before bedtime.
• Create a relaxing bedtime routine. That means turning off electronic screens at least an hour before hitting the sack. Also, dim the lights after dinner. That will signal your brain to increase its melatonin production.
• Exercise during the day but avoid workouts close to bedtime. “Just 15 minutes a day can help you sleep better,” she says.
• Spend time in natural light, especially in the morning after waking up, to help regulate your body clock.
• Avoid naps in the late afternoon. And if you do snooze in the day, keep it to 20 or 30 minutes.
• Consult a board-certified sleep specialist if you’re still having sleep issues. Cognitive Behavioral Therapy is now the first-line treatment for chronic sleep problems, before medication.  “Insomnia is often a symptom of something else – depression, anxiety, stress, and you have to address those,” Dr. D’Ambrosio says.
• Safeguard your sleep as fiercely as you protect your passwords. Sleep helps regulate metabolism, boost immunity, improve mood and support brain function.

“We spend about one-third of our lives sleeping,” she adds. “That should make people realize how important sleep is. It’s the foundation of good health.”

Written by Ana Veciana-Suarez.

Tags: Dr. Carolyn D'Ambrosio, Side effects of melatonin, sleep aids, Sleep quality, sleep supplements