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melatonin |
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melatonin: see pineal gland pineal gland (pĭn`eəl), small organ (about the size of a pea) situated in the brain . ..... Click the link for more information. . melatoninHormone secreted by the pineal gland of most vertebrates. It appears to be important in regulating sleeping cycles; more is produced at night, and test subjects injected with it become sleepy. Melatonin may be involved in seasonal affective disorder. In mammals other than humans, melatonin may act as a cue to breeding and mating in season. melatonin [‚mel·ə′tōn·ən] (biochemistry) A hormone secreted by the pineal gland that acts on melanophores in the skins of amphibians and reptiles to concentrate the melanin in the center of the cells, lightening the body surface; in higher vertebrates it conveys information about time that influences reproduction and circadian physiology. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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The longer exposure to light reduces the duration of melatonin secretion each day because light inhibits the release of melatonin. One possible explanation for the shift-work effect is that the hormone melatonin might protect men against prostate cancer, says Stevens. By measuring levels of melatonin in saliva, scientists can see what time the master clock thinks it is. |
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