Melatonin, all about the drug that should not be taken as if it were a nutritional supplement

• Health Sleep, the guardian of your health
• Health These are the risks of too little and poor sleep

The latest study by the Spanish Sleep Society (SES) estimates the prevalence of chronic insomnia in the adult population of our country at 14% (estimated by the INE at around 38 million in 2022), which means that it has doubled since 2000 and confirms the importance of this disease.

Children are also not spared from problems, mainly difficulty initiating and maintaining sleep (the most frequent), respiratory disorders, parasomnias, circadian rhythm disorders (adolescence) and restless legs. Globally, they affect 30% of children (about two million children under 16 years of age).

Against this backdrop, interest in using melatonin in the treatment of these conditions has not stopped growing. There are several factors that motivate this trend. It is a hormone secreted by the pineal gland with a circadian rhythm, which helps regulate the oscillation between sleep and wakefulness. In addition to this chronoregulatory effect, there are immunological, antioxidant and oncostatic properties. In addition, it is easily synthesized and administered orally.

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Its natural secretion is related to changes in light and dark, along with other external synchronizers, such as diet, social habits, and exercise. Its production decreases with age in a relationship inversely proportional to the frequency of poor sleep quality. This fact has reinforced the idea that their deficit is, at least in part, responsible for this type of disorder.

However, the efficacy of exogenous administration depends on the indication being well made and being taken when appropriate. "You have to give it to whomever it touches, how it touches and with medical control because it is a drug," sums up Óscar Sans, coordinator of the SES Paediatric Group. "The success of melatonin has to do with how it occurs, but above all when," emphasizes Ainhoa Álvarez, neurophysiologist and coordinator of the SES Insomnia Group, which is why she considers the doctor's intervention essential.

The latest study published by the SES Insomnia Group concludes that, as the main regulator of the rhythm of wakefulness and sleep, melatonin is a substance of "great interest" to address the problems of insomnia and sleep phase disorders: "Accentuating the physiological signal that makes us fall asleep seems to be the most natural approach to deal with these alterations. Especially when they occur at ages when melatonin synthesis is decreased. The data we have, mainly with extended-release melatonin, indicate that it is effective, both in primary insomnia and in that associated with other neurological diseases, especially in people over 55 years of age."

Necessary medical regulation and control

The SES maintains that it is undeniable that melatonin is a drug and that as such it must be handled with the required quality controls. Its regulation is necessary, as well as medical control and prescription dispensing in adults and children.

"These products do not have clinical trials, pharmacokinetic or pharmacodynamic studies," says Ainhoa Álvarez. In a letter sent to Public Health, the SES Paediatric Group already warned that these children's formulas have production processes "that produce great variability in both their composition and bioavailability". And it concluded that melatonins available as a food supplement "are less safe and less effective for the treatment of insomnia."

"The problem we are having with children is that they already come to us with melatonin on," laments Óscar Sans, who warns that poor administration can cause a major sleep disorder: "It will not be a catastrophic effect but in the medium term it will not work and people will stop taking it."

The head of the Paediatric Group believes that the prescription is a necessary step for the doctor to have control and not to use it indiscriminately, in addition to ensuring that the drug is financed by the health system because the expense in serious cases can be very high.

In fact, this group of experts has already made a formal request to the administration for funding of Slenyto in patients with neurological disorders and Ciercadin for off-label use in children with the same indications as Slenyto.

In Spain, Circadin and Slenyto, both extended-release, are marketed as drugs. "Studies with Circadin show that it improves sleep in people over 55 years of age. They are not as powerful drugs as hypnotics, but they help you sleep," says Ainhoa Álvarez. Slenyto is used in pediatrics, where Circadin has an off-label use. Óscar Sans supports the efficacy of melatonin in children when there is difficulty in initiating sleep, in adolescents with phase delay problems and neurodevelopmental disorders.

It is important to clarify the indications. According to the coordinator of the Insomnia Group, in adults there are basically two and the pattern is different. One is phase delay disorders. These patients should take melatonin twelve hours before waking up because it is used as a circadian rhythm regulator. In insomnia, and when there are no added disorders such as anxiety, depression or chronic pain, half an hour before bedtime and it is essential to reinforce sleep hygiene. The usual dose is between 1 and 3 mg per day.

SES specialists warn that there are many products marketed as dietary supplements and therefore subject to much less strict regulation and control mechanisms, which can be purchased in herbalists and supermarkets. Even preparations adapted for children due to their presentation in drops, sprays or gummies.

In the paediatric age

With children, it should not be used before they reach the first year of life, because circadian rhythms are not mature. Nor is any type of treatment recommended without first working with correct routines. As Óscar Sans explains, they are twenty-four-hour measures, which have to do with sleep and eating schedules: "The gut is our second brain and we don't take it into account. If I eat late, I'll go to sleep later because the brain understands that it doesn't play."

The pediatrician must keep a sleep diary to know how the child sleeps and when sleep begins to know what time to administer melatonin, which will be an hour before. The indication is that there are difficulties in initiating sleep and the dose is usually 0.5 to 3 mg. "If there are nocturnal awakenings (three or more during the night), you have to check that they are not due to other causes, such as a respiratory disorder or that ferritin is below 50 mg/liter." In adolescents, a phase delay may occur, which is linked to this stage of life, although screen abuse may be involved. The time to take melatonin is between four and six hours before the time when the patient usually falls asleep.

In children with neurodevelopmental disorders, it is also useful, especially on the autism spectrum: "Studies show that they improve the onset and maintenance of sleep." Here you can increase the dose up to 6 mg.

Melatonin drugs are well tolerated, they do not cause addiction or their withdrawal a rebound effect. Regarding this exogenous administration, Óscar Sans asserts that "it is better to sleep with melatonin at minimum effective doses than not to sleep at all".

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