Melatonin does not affect how deeply you sleep, but it greatly influences how sleepy you become each day. Melatonin gets released into your body mostly after dusk. When light dissipates, and your brain perceives darkness, the hormone level increases. In a natural setting without flashing billboards and overhead kitchen lights, melatonin activity initiates at sunset. It continues for a few hours until it reaches a peak that cues you to go to sleep. Like adenosine, as melatonin builds in the system, we become sleepier.
