Melatonin wani hormone ne wanda glandan pineal na kwakwalwa ke ɓoye a cikin dabbobi masu shayarwa da mutane.Domin yana iya yin sel da ke samar da hasken melanin, don haka sunan melatonin, wanda aka fi sani da pineal hormone, melatonin, melatonin.Bayan an haɗa melatonin kuma an adana shi a cikin jikin pineal, jin daɗin jijiya mai tausayi yana sa ƙwayoyin pineal su saki melatonin.Sirrin melatonin yana da rawar gani na circadian a fili, wanda ake dannewa da rana kuma yana aiki da dare.Melatonin na iya hana hypothalamic-pituitary-gonadal axis, rage abun ciki na gonadotropin sakewa hormone, gonadotropin, luteinizing hormone da follicle stimulating hormone, kuma zai iya kai tsaye aiki a kan gonads don rage abun ciki na androgen, estrogen da progesterone.