Melatonin is the ‘‘Chemical Signal of Darkness’’. Because the duration of melatonin production is the neurochemical signal for the annual change in night length,1Wehr TA, Duncan WC Jr, Sher L,
Melatonin is the ‘‘Chemical Signal of Darkness’’. Because the duration of melatonin production is the neurochemical signal for the annual change in night length,1Wehr TA, Duncan WC Jr, Sher L,
