“Melatonin is not a treatment of choice for sleep disorders: uncertain efficacy beyond a placebo effect, it exposes to adverse effects, in particular neuropsychic, cutaneous and digestive. This is what can be read in the latest issue of Prescrire . In France , according to the dose contained in a unit of intake, this hormone is considered a drug or a food supplement. It is only from 2 mg per dose that it has the drug status, indicated in “primary insomnia in patients aged 55 years or older”. But some food supplements may contain 1.9 mg and be marketed with a claim of the type: “helps to reduce the time of falling asleep”.
Melatonin is a hormone secreted mainly in the brain by the epiphysis (also called the pineal gland), but also by the retina, intestine, skin, platelets and bone marrow. Its main function is to inform the body of the day-night alternation, which makes it easier to fall asleep. But, as recalled in the medical monthly, it seems to have other effects, including mood, immune system, intestinal mortality and sexual behavior (it would increase libido). It is also involved in the regulation of body temperature.
90 side effects
From 2009 to May 2017, the National Food Safety Agency ( ANSES ) collected 90 adverse effects related to the consumption of food supplements containing melatonin. As for the National Agency for the Safety of Medicines ( ANSM), it collected more than 200 melatonin-related adverse events, regardless of its status, between 1985 and 2016. These were mainly neurological disorders (syncope, drowsiness, headache, seizures in 43% of cases) and psychic (anxiety, depressive disorders in 24%), as well as skin problems such as various rashes and digestive disorders (vomiting, constipation, pancreas involvement). Heart rhythm disorders have finally been observed. Fortunately, they regress with stopping the intake of this hormone.
Prescrire also points out that interactions are possible with many drugs. They are likely to decrease their effectiveness and / or to add up their undesirable effects. To this must be added the fact that “abnormal data observed in animals call for the greatest caution regarding the use of melatonin during pregnancy”, even though the studies were carried out with very high doses, and that ” Possible long-term toxicity has hardly been explored ‘. Under these conditions, we can better understand the call for caution once again made by the authors of this article. Their conclusion is clear: “Melatonin is not a treatment of choice for sleep disorders. “