What are the effects of melatonin on sleep?

Sold without a prescription in the form of a food supplement, this synthetic hormone can in certain cases promote sleep, although side effects have nevertheless been reported to the National Agency for Food, Environmental and Occupational Health Safety (ANSES).

Are melatonin-based products, which can be found in pharmacies in the form of capsules or flavored gums, really effective in promoting sleep? Inserm, the national institute for medical research, published a note on Wednesday, September 25, to reestablish some truths. In the form of food supplements, melatonin is sold without a prescription. It is a growing market with more than 700 new product references appearing in France over the past five years.

Melatonin is a hormone naturally synthesized by our brain to synchronize the sleep-wake cycle. Its concentration naturally increases at the end of the day to signal to the body that it is time to sleep. Synthetic melatonin contained in food supplements therefore allows us to force nature a little to promote sleep, explains Claude Gronfier, chronobiologist and researcher at Inserm. Various studies have shown that in the general population, these supplements can indeed shorten the time it takes to fall asleep a little, especially in people over 55, but this is not systematic.

Effectiveness also depends on caffeine consumption, tobacco, possible interactions with medications, or the existence of underlying diseases. No beneficial effect on the quality of sleep that follows has been proven. While other benefits have sometimes been mentioned, such as, for example, the relief of migraines, or the stimulation of immunity, these effects are not based on solid scientific data, recalls Inserm.

There are risks of toxicity, even if they are rare. Some side effects have been reported to the French National Agency for Food, Environmental and Occupational Health and Safety (ANSES), such as headaches, nausea, drowsiness, or dizziness. Be careful, therefore, not to exceed the recommended doses. Furthermore, while in the United States, the market for melatonin candies is growing and half of Americans admit to having given this hormone to their child to help them sleep, taking melatonin requires medical advice before any use in children and adolescents, as well as in pregnant women, people suffering from inflammatory diseases, epilepsy, or mood disorders, doctors warn.