Melatonin, chemically known as n-acetyl-5-methoxytryptamine, is a compound containing indole rings. Endogenous melatonin is a hormone secreted by the pineal gland, a neuroendocrine organ near the upper midbrain, which is synthesized mainly from tryptophan. Endogenous melatonin plays a physiological role in regulating circadian rhythm and sleep.

Studies have shown that melatonin can improve sleep by increasing sleep time and shortening sleep time for people with sleep disorders. In terms of the specific mechanism, some studies believe that with the growth of age, the secretion of melatonin in the human body gradually decreases, resulting in sleep problems for some elderly people. Therefore, the elderly can take exogenous melatonin to supplement the lack of melatonin in the body to improve sleep and other effects. There are also literature pointed out that when people are 1-3 years old, the secretion of melatonin in the body has reached the peak in their life, and then the secretion has declined year by year, and the decline has become slow after puberty, and the secretion has no longer declined by about 30 years old. Most older adults aged 65-84 have roughly the same plasma melatonin concentration as younger adults. There is no scientific proof that melatonin can delay aging.

Different countries and regions have different standards and regulations for the use of melatonin. In the United States, melatonin is approved by the Food and Drug Administration (FDA) for use as a dietary supplement ingredient and does not require government approval to be marketed. In the European Union, melatonin is not allowed to be used as a food ingredient. The Australian Drug Administration has approved melatonin as a drug. In Canada, melatonin is allowed to be used as an ingredient in natural health products, and the recommended daily dosage for adults ranges from 0.5 to 10mg. In China, melatonin is allowed to be used as a raw material for health food, the purity is required to be more than 99.5%, the recommended daily dosage is 1-3mg, and the declared health function is limited to improving sleep.