The role of melatonin in the regulation of circadian rhythm and sleep quality: narrative review
Abstract
Background: Melatonin is a pineal hormone involved in the regulation of the human circadian rhythm and sleep. Its secretion depends on the light dark cycle and decreases with age, which contributes to sleep disturbances in older adults. Circadian rhythm disorders are common in shift workers and in individuals exposed to time zone changes, which makes melatonin an important subject of clinical interest. Aims: The aim of this narrative review was to summarize current data on the role of melatonin in circadian rhythm regulation and sleep quality in different patient groups, with particular attention to older adults and shift workers. Methods: This review was based on the analysis of sixty five publications identified in the Polska Bibliografia Lekarska and PubMed databases for the years 2015 to 2025. Included sources described melatonin synthesis, secretion patterns, physiological functions, clinical characteristics of sleep disturbances, and the use of melatonin in endogenous and exogenous rhythm disorders. All sixty five studies were analyzed descriptively according to the standards of narrative reviews. Results: The reviewed literature shows that melatonin improves sleep quality, reduces sleep latency by several minutes, and supports the organization of the sleep–wake cycle in individuals with rhythm disturbances. Age related secretion patterns are documented, with the highest melatonin levels in early childhood and a marked decline after the age of forty. Antioxidant and…
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