Melatonin
/mˌɛləˈtoʊnɪn/
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Definition
(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 and wake and reproductive cycles in mammals.
Sentence Examples
The pineal gland secretes melatonin.
Melatonin helps to regulate circadian rhythms.
CEFR Practice Quiz
Some people take ____ supplements to help regulate their sleep patterns when traveling across time zones.