Melatonin is a natural hormone produced in the brain by the pineal gland. The production and release of melatonin is stimulated by darkness and suppressed by light. It is only relea
sed during the night.
Moreover, Melatonin refers to a hormone released by the pineal gland in response to daily cycles of light and dark; a hormone that among other effects induces sleepiness.
Lexicon of Psychology - Terms, Treatments, Biographies,