In cases of insomnia, many turn to melatonin, this hormone naturally produced by the pineal gland which regulates our biological clock. In the synthetic version, it promises faster falling asleep and a more stable sleep-wake rhythm. However, recent research calls for caution.
Melatonin, a “help” for sleep, but not without risks
Presented during the 2025 scientific sessions of the American Heart Association, a study reveals that prolonged use (beyond twelve months) of melatonin supplements is associated with a 90% increase in the risk of heart failure in adults suffering from chronic insomnia.
SUNY Downstate Health Sciences University researchers analyzed more than 130,000 medical records of adults with an average age of 56.
Their finding: those who consumed melatonin over the long term were 3.5 times more likely to be hospitalized for heart failure and twice as likely to die from all causes than those who did not take it.
For Dr. Ekenedilichukwu Nnadi, lead author of the study, “Melatonin supplements are widely considered a safe and natural option to promote better sleep.”. But, he specifies, “they might not be as harmless as is commonly thought.”
What experts say about the link between melatonin and the heart
Dr. Gérald Kierzek, emergency physician and medical director of True Medical, recalls the role of melatonin. “It facilitates falling asleep and regulates biological sleep rhythms” he explains first of all.
The molecule works in particular by lowering body temperature to prepare the body for sleep. “It also induces vasodilation of peripheral arteries, which influences blood circulation and can have an effect on the heart.”
According to our expert, in the long term, this vasodilator action could increase the risk of heart failure in fragile people, particularly those suffering from cardiovascular pathologies or following specific treatments.
“Prolonged taking of melatonin could interact with certain medications and accentuate cardiac side effects. he adds.
However, the authors of the study are cautious: their work opens a serious avenue but does not prove a cause and effect link, taking melatonin could be a factor associated with the real cause.
“More severe insomnia, depression or use of other sleep-promoting medications could be linked to both melatonin use and heart risks.”
recognizes Dr. Nnadi.
In France, melatonin is accessible to different categories of people depending on their age. It is available in pharmacies:
- Without prescription for doses up to 1 mg;
- With prescription for the 2 mg version, intended for people over 55;
- A temporary prescription may also be considered for children.
In the first case, melatonin is generally consumed as a food supplement, in the form of capsules or tablets.
According to data from Anses, the National Agency for Food, Environmental and Occupational Health Safety, more than 1.4 million boxes of food supplements containing melatonin are produced and marketed each year in France. In 2018, ANSES recommended against the consumption of melatonin for pregnant and breastfeeding women, children and adolescents, people suffering from inflammatory, autoimmune diseases, epilepsy, asthma, mood, behavioral or personality disorders, as well as people following drug treatment.
How to sleep better without relying on melatonin?
Before turning to supplements, Dr. Gérald Kierzek emphasizes non-drug solutions:
- Adopt regular sleep hygiene (fixed schedules, temperate room, avoid blue light in the evening);
- Practice relaxation techniques such as breathing or meditation;
- Consider gentle herbal alternatives like valerian, passionflower or poppy.
“Melatonin can be useful in the short term, particularly for circadian rhythm disorders linked to jet lag or irregular schedules. But it must be used under medical supervision if taken for a prolonged period to limit cardiac risks. he concludes.