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An animal hormone, C13H16N2O2, derived from serotonin and produced by the pineal gland. It stimulates color change in the skin of amphibians and reptiles and plays a role in regulating circadian rhythms and reproductive cycles in mammals. It is also found in plants and fungi.

[Greek melās, black + ton(e) + -in.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Biochemistry) the hormone-like secretion of the pineal gland, causing skin colour changes in some animals and thought to be involved in reproductive function
[C20: probably from mela(nocyte) + (sero)tonin]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˌmɛl əˈtoʊ nɪn)

a hormone secreted by the pineal gland in inverse proportion to the amount of light received by the retina, important in regulating biorhythms.
[1955–60; < Greek mélā(s) black + tone + -in1]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


A hormone influencing the onset of puberty, the menstrual cycle, and the body’s daily activity cycle. See also pineal gland.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.melatonin - hormone secreted by the pineal gland
endocrine, hormone, internal secretion - the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.


n melatonina
English-Spanish/Spanish-English Medical Dictionary Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
References in periodicals archive ?
And when tested in combination with six different chemotherapy drugs (for a variety of different types of cancer), using melatonin (20 mg/day) in addition to the drugs resulted in:
Objective: To find out the effect of melatonin as adjunct therapy on outcome of admitted newborns presenting with hypoxic ischaemic encephalopathy.
Melatonin administration shows promise in the management of periodontal diseases.
Two components of foods that are shown to be most helpful in improving sleep quality are melatonin and tryptophan.
I'm talking about melatonin. And when you hear about all of the things that researchers are discovering about melatonin, you're going to be absolutely amazed.
Objective: To explore the nephropreventive effects of melatonin on vancomycin-induced nephrotoxicity in rabbits.
Melatonin (N-acetyl-5-methoxytryptamine) is an important lipophilic amine hormone that is secreted by the pineal gland and considered a powerful free radical scavenger It plays a critical role in the physiology of the ovary in the reproductive system [1].
[USA], May 16 (ANI): Melatonin is a hormone known to promote sleep but ever wondered how?
Melatonin is said to be a synthetic form of a naturally occurring hormone in a person's body, produced by the pineal, which regulates circadian rhythms, that controls the body's sleep cycle.
THE BLUE light emitted from our cellphones, tablets and laptops can interfere with melatonin production, so many people purchase melatonin as an oral supplement to help them fall asleep.
Traditional nonprescription melatonin supplements have been available for more than two decades.