1. Hormone postulated to mediate photoperiodicity in mammals. Inhibits cerebellar nitric oxide synthetase
2. Melatonine can be used in sleep induction, modifies circadian rhythm, antioxidant, free radical scavenger
3. Immunostimulant;Melatonin receptor ligand
4. Melatonin has complex effects on apoptotic pathways, inhibiting apoptosis in immune cells and neurons but enhancing apoptotic cell death of cancer cells. Inhibits proliferation/metastasis of breast cancer cells by inhibiting estrogen receptor action.