Circadian rhythm is an essential biological process that regulates the sleep-wake cycle，hormone secretion，and metabolism，and the stability of circadian rhythm is crucial for maintaining normal cognitive function. Melatonin （MT），a key hormone secreted by the pineal gland，is involved in the regulation of circadian rhythm and thus has a significant impact on cognitive function. This article systematically reviews the multiple mechanisms by which MT regulates cognitive function through circadian rhythm，including improving sleep quality，promoting the clearance of metabolic waste by the glymphatic system，exerting antioxidant and anti-inflammatory effects，and regulating neuronal activity and the improvement of synaptic plasticity. In addition，this article also discusses the association between circadian rhythm disorders and neurodegenerative diseases. Future studies are needed in the future to further clarify the neuroprotective mechanisms of MT，in order to provide new insights for the prevention and treatment of cognitive impairment.
Melatonin