hormone antioxidant melatonin 2018-11-19T14:33:05Z A biogenic amine that is found in animals and plants. In mammals, melatonin is a hormone produced by the pineal gland. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of sleep, mood, and reproduction. Melatonin is also an effective antioxidant. CHEBI:16796 XCO:0000559 experimental_condition_ontology sjwang