**Abstract**

Sleep disorders are a group of conditions that affect the circadian rhythm of sleep-wake, leading to social and professional maladaptation. At the moment, there is a wide range of medications aimed at the treatment of sleep disorders, but the results from their use are not always satisfactory. Benzodiazepines, antidepressants, and antihistamines may cause dependence or withdrawal effects. Melatonin (N-acetyl-5-methoxytryptamine) is an endogenous hormone produced by the pineal gland that affects intraday, seasonal rhythm, and the sleep-wake cycle. Studies of the effects of melatonin have demonstrated its ability to synchronize circadian rhythms, reduce the latency of slow sleep, increase the duration of sleep, and improve its subjective quality. This review highlights the current therapeutic possibilities of using melatonin in various sleep disorders, taking into account the mechanisms of its action. Also, the prospects of using melatonin due to its chronobiological effect in other sleep disorders, such as parasomnia, sleep-dependent respiratory disorders, and hypersomnia, are emphasized. At the moment, melatonin is one of the methods for correcting intraday rhythms and some types of insomnia.

**Keywords:** sleep, melatonin, sleep disorders, sleep-wake cycle
