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11 min read
What is melatonin and how does it function?
Lena Bauer
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Diets Premium Expert • 24.09.2026
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Scientifically reviewed by a clinical dietitian:
This article has been peer-reviewed for adherence to IŻŻ, WHO, and PTGiP clinical nutritional standards.
| Diets Premium Expert Lena Bauer | min read 11 min | Scientifically reviewed by a clinical dietitian 24.09.2026 |
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Key Takeaways
Over the years, there has been a significant increase in sleep disorders such as insomnia and inefficient sleep, which affect our daily functioning. Furthermore, evolving lifestyle trends such as late-night meals or excessive consumption of high-calorie dishes can result in disturbances in the sleep cycle and overall daily rhythm, potentially leading to the development of various diseases. The hormone melatonin, responsible for regulating sleep, plays a crucial role in this context. Read the article to learn more about the mechanism of action, dosage, and side effects of melatonin.
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Melatonin and its salts, whether or not containing added sugar or other sweetening matter
Melatonin is a secretory hormone, and actually an indolamin, synthesized and secreted by the esophagus at night. Additionally, melatonin is produced by the enterochromophine cells of the mucous membrane of the digestive tract. It was first isolated in 1958. Its full name is N-acetyl-methoxytryptamine, but it is more commonly referred to as the dark hormone. Its concentration in the urine at night is about 80 100 pg/ml, however, it is much lower than 10 20 pg /ml.
Melatonin is effective
According to this source, its deregulation may be closely related to the occurrence of metabolic syndrome, including diabetes and obesity. It demonstrates a significant role in neuroimmunomodulation. In addition, it acts as a natural anti-oxidant with immunostimulatory and anti-cancer properties, which is also considered to promote sleepiness. According to these sources, its deterioration may be strongly linked to the development of the metabolic system, including diabetic and obese patients. It also appears to increase the effectiveness of the immune system, as well as its effects on the health of young people, including the progression of long-term cancer cells.
Melatonin for sleep
Melatonin mainly functions as a sleep modulator. This activity is well documented. Due to its deteriorating synthesis in the elderly, it is sometimes recommended to supplement it, especially > 55 years of age with simultaneous insomnia. Its effective effects have been reported in both diarrheal disorders and delayed or advanced sleep disorder and in the alleviation of the effects of shift work. It is also useful in people who are blind. Its supplementation increases sleep quality and duration.
I'm pregnant with melatonin
Melatonin, as I have already mentioned, is produced in the bladder, which does not reach maturity until 6 to 12 weeks of life, so breastfeeding at this time is really important. It is from the mother's milk that it is delivered to the base level after birth. During pregnancy, therefore, it is supplied from the body of the mother and the fetus by all the physiological barriers, including the placenta, without any modification. Moreover, its production does not begin until the 6-12th week of life. So breast feeding during this period is very important.
Melatonin for children
Melatonin is used, as I have already mentioned, not only in adults but also in children and infants. It is used to improve sleep or learning difficulties, as well as in sepsis. Importantly, it is completely safe, even when treated with other pharmaceuticals. In addition, in newborns with respiratory disorders, it delays the development of autosomal recessive dysplasia and chronic lung disease. Moreover, it has been shown to reduce the effect of pro-inflammatory hormones and at the same time improve clinical outcomes.
Melatonin is contraindicated
Many pharmaceutical preparations interact with other products. Melatonin, although very safe, inhibits prostaglandin synthesis. Due to its important role in the functioning of the circulatory system as well as the hormonal system in the fetus, this should be noted before supplementation. Care should be taken by those who also take fluoxamine, which increases its concentration.
The melatonin dose
The dosage of melatonin varies according to the age and health status of the patient. 16 mg per hour before bedtime is recommended for the blind. The same dosage is for sleep and wakefulness disorders. The situation is somewhat more complicated in pathology related to time zone changes.
Overdosage of melatonin
According to scientific sources, high doses of melatonin do not adversely affect fetal development. Additionally, a high dose is not associated with deterioration in the well-being of both the baby and the mother, nor does it alter the activity of the uterine muscles during late pregnancy. Extensive meta-analyses have shown that the toxicity of this hormone is extremely low and does not cause serious adverse side effects, even at extremely high levels.
What are the side effects of melatonin?
Although melatonin is considered to be extremely safe, as with all other pharmaceutical preparations, moderation should be observed. Additionally, adverse reactions are sometimes reported, e.g. increased seizure activity in children with neurological disorders treated with this hormone. It is important that its use does not disrupt the sleep phase and even regulates it. However, as mentioned above, no dependence or symptoms of intolerance have been reported.
Melatonin in food
Melatonin is a hormone produced by our body. The substrate for its production is tryptophan, which is an amino acid found in many food products. It is converted in the human body into serotonin, which in subsequent changes, depending on the circadian rhythm, gives melatonin. Its consumption can result in improved sleep and improved quality for low-intensity sleep disorders.
Lena Bauer
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