What is melatonin's main function? what are its other functions?

melatonin is a hormone secreted by the pineal gland and its main function is to regulate sleep rhythm (circadian rhythm)

Melatonin mediates function through, antioxidant action in most of disorders. Melatonin is a chronobiotic substance that acts as synchronizer by stabilizing bodily rhythms. Its synthesis occurs in various locations throughout the body, including the pineal gland, skin, lymphocytes and gastrointestinal tract (GIT)