The substance, popularly known as the “sleep hormone”, was released for sale in the country on October 15, 2021 by the National Health Surveillance Agency, Anvisa.
Although the decision is in line with what is happening in several countries in Europe and North America, experts heard by BBC News Brasil criticize the decision and ask for great caution when buying and using this product.
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“It is worrying that melatonin is sold like a popsicle. We are not talking about an innocuous substance and its wrong use can bring problems”, warns neuroscientist Fernando Mazzilli Louzada, coordinator of the Chronobiology Laboratory at the Federal University of Paraná (UFPR) .
“And it is a strange concept to frame it as a food supplement. There is no consensus on when there is a deficiency of this hormone in the body”, points out neurologist Dalva Poyares, a researcher at the Instituto do Sono de São Paulo. “There is not even a guideline in the world that indicates melatonin as a treatment for insomnia”, adds the specialist, who is also a professor at the Federal University of São Paulo (Unifesp).
“We need to make it clear that melatonin can even be a therapeutic tool, but it will not be indicated for everyone”, agrees doctor Paulo Augusto Miranda, vice president of the Brazilian Society of Endocrinology and Metabolism (SBEM).
But, to understand all this controversy, it is necessary to know beforehand what melatonin is and its importance for the functioning of the body.
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the twilight mistress
“It is very beautiful to think that day and night are incorporated into our body by melatonin”, reasons Louzada.
This hormone is produced by the pineal gland, a structure that sits at the very center of the brain.
And there is a very important aspect to this manufacturing process: it only happens in the absence of light.
As night falls and the sun sets, the production of melatonin starts to take place in our heads. The goal is to prepare the body for sleep during the night period.
“Have you ever stopped to think about how the liver, the stomach, all the other organs and the metabolism itself know whether it is day or night? The signaling of time, of 24-hour cycles, is given precisely by melatonin”, explains the professor of UFPR.
At the dawn of a new day, when light reappears, melatonin production is stopped, which prepares the body to wake up and prepare for daily activities.
But this sleep-wake cycle, largely dictated by this hormone, can be disrupted by a number of factors, starting with exposure to light at night.
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“Since humanity started to live with electricity, there has been a change in the secretion of melatonin. If I stay awake until midnight watching TV or using my cell phone, this substance will end up inhibited”, adds Louzada.
With low melatonin, the quality of sleep, or even the amount of hours slept, ends up impaired.
But, in addition to the comforts of the modern world, the production of sleep hormone can also be affected by some specific illnesses or by aging itself – elderly people tend to produce a lower amount of melatonin compared to younger people.
But can taking a supplement solve some of these problems?
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Upon announcing that it had released melatonin on October 15, Anvisa argued that “the substance in question is already used in several countries as a food supplement and as a medicine, with varying conditions of use.”
The agency also stated that it decided to evaluate the safety and effectiveness of the molecule “due to the interest of consumers and the productive sector in accessing and offering products containing this substance”.
Before, this product was only available in compounding pharmacies, with a prescription signed by a doctor.
Although melatonin is now classified as a food supplement and can be purchased over-the-counter at conventional drugstores, Anvisa has imposed some restrictions on its use.
The first is that it can only be taken by people over 19 years of age and the dosage is, at most, 0.21 milligrams per day.
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In other places, such as the United States and Europe, it is possible to find much larger doses, reaching up to 5 mg.
The Brazilian regulatory body also determined that the packaging must contain a warning that this product should not be consumed by “pregnant women, breastfeeding women, children and people involved in activities that require constant attention”.
In addition, it is advised that individuals with any illness or taking medications seek medical attention before consuming this supplement on their own.
Poyares assesses that the dose approved in the country, 0.21 mg, is very close to what is produced on average by the body itself, which reduces the risk of more worrying adverse events.
On the other hand, this amount may not be enough to serve as a treatment for people who really have a sleep disorder and who would eventually even benefit from an extra load of melatonin.
“There is still no consensus on what is the appropriate dose to obtain a therapeutic effect in patients who are indicated for use”, says the neurologist.
The specialist also points out that large-scale tests are not available to measure the amount of sleep hormone and determine whether there is a deficiency of it in the body.
“Melatonin is not the same as vitamin D, which we can easily measure in the blood and see if there is a need for supplementation or not”, he compares.
“In other words: no one knows when it is really necessary to ‘replace’ melatonin. Therefore, we do not have scientific evidence of the benefit of supplementing this hormone in the general population”, he concludes.
Elderly people with difficulty sleeping may benefit from a melatonin supplement, provided they have had a medical evaluation — Photo: Getty Images via BBC
When the supplement can help
Although the topic is full of controversy, doctors admit that melatonin replacement can help in some very specific scenarios.
“An elderly individual who has difficulty sleeping, for example, would benefit from supplementation, as long as there is an evaluation and a medical prescription”, defends Miranda, from SBEM.
“There are also some very specific sleep disorders that are treatable with this substance,” he adds.
A third indication would be for those individuals traveling to another country with a very different time zone. In these cases, the supplement would facilitate entry into the new routine without experiencing the phenomenon of jet lag — a temporary sleep disorder in which the biological clock is out of sync with local time.
“And it is noteworthy that, contrary to what some advertisements and posts on social networks say, there are no studies proving that this supplement helps to control or lose weight”, calls the attention of the endocrinologist.
Before buying the product at the pharmacy, therefore, it is worth seeking out a specialist if you are constantly having difficulty falling asleep (or staying asleep), snore at night, are drowsy throughout the day, or have that feeling that the night rest was not restorative.
This professional, who usually has a background in sleep medicine or chronobiology, can make an in-depth assessment and understand the reasons behind all these difficulties.
“Often, before thinking about prescribing melatonin, we can try a series of changes in behavior and habits to improve the quantity and quality of sleep”, says Louzada.
Doctors often call these interventions sleep hygiene. One of the main changes is precisely to increase exposure to light during the day and reduce contact with screens and lamps at night.
This change can already make all the difference in the natural production of melatonin and guarantee a better quality of rest.
“We do not correct wrong habits with medication. Most of the time, we need to change these habits to achieve a better quality of life”, agrees Miranda.
“And, even in cases where there is really a need for melatonin supplementation, it is necessary to think very carefully about the dosage and time of ingestion of the product”, points out Louzada.
“The sensitivity to melatonin varies a lot from person to person and monitoring with a health professional is necessary to avoid the opposite effect to the desired”, he suggests.
The most common adverse events from taking melatonin wrongly are headache, irritation and drowsiness throughout the day.
“In the long term, however, the main problem of inappropriate use is that the supplement may not solve the sleep-related complaints that that person has. Therefore, medical monitoring is so important”, concludes Miranda.