title: Melatonin secretion as a mediator of circadian variations in sleep and sleepiness.
mesh_terms: D002940:Circadian Rhythm; D006801:Humans; D008550:Melatonin / Q000378:metabolism*; D010870:Pineal Gland / Q000378:metabolism*; D012890:Sleep / Q000502:physiology*
chemical_list: D008550:Melatonin