melatonin

  1. Noun.  A hormone, related to serotonin, that is secreted by the pineal gland, and stimulates colour change in the skin of reptiles, and is involved in the sleep/wake and reproductive cycles in mammals.
  2. Noun.  Any material similar in its chemistry and effect to the natural hormone.

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This entry was last updated on RefTopia from its source on 3/20/2012.