melatonin

noun

mel·a·to·nin ˌme-lə-ˈtō-nən

: a vertebrate hormone that is derived from serotonin, is secreted by the pineal gland especially in response to darkness, and has been linked to the regulation of circadian rhythms

Example Sentences

Recent Examples on the Web Muscle Milk Sleeping Giant line of protein powders has casein protein, a little bit of melatonin, and some tart cherry powder, which has been found to aid in muscle recovery, according to Current Sports Medicine Reports. —

Cori Ritchey, Men's Health, 9 Mar. 2023 These gummies are specially formulated with high quality melatonin and spirulina extract. —

Amber Smith, Discover Magazine, 10 Nov. 2022 Trump received an experimental polyclonal antibody cocktail, the antiviral drug remdesivir, vitamin D, zinc, famotidine, a daily aspirin, and melatonin. —

Zachary Halaschak, Washington Examiner, 10 Oct. 2020 During these flights, pilots wore brainwave monitors and had their urine tested in the weeks before and after the flights to track levels of melatonin, a hormone that controls sleep cycles. —

Maggie Hiufu Wong, CNN, 23 Feb. 2023 Skip the melatonin and instead rake a dollop of Christophe Robin Night Recovery Cream from your mid-lengths to the ends of your hair before bed. —

Lisa Desantis, Allure, 21 Feb. 2023 Our daily cycles of melatonin and other sleep hormones are disrupted, with sometimes dire effects. —

Adam Gopnik, The New Yorker, 20 Feb. 2023 Tart Cherry Juice and Sleep Efficiency All cherries contain melatonin, a chemical widely known to induce sleepiness and prevent insomnia. —

Daphne Yao, Health, 17 Feb. 2023 Research suggests melatonin, the hormone released for sleep, may decrease glucose tolerance and explain why the body has a more difficult time metabolizing late-night meals. —

Byalexa Mikhail, Fortune Well, 15 Feb. 2023 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'melatonin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

Etymology

mela-, extracted from Greek melan-, mélās "black, dark" + -tonin (in serotonin); so named because the hormone can lighten skin color in animals by reversing the effect of melanocyte-stimulating hormones — more at melano-

Note: The word was probably introduced in the first published description of the hormone's isolation: Aaron B. Lerner, et al., "Isolation of melatonin, the pineal gland factor that lightens melanocytes," Journal of the American Chemical Society, vol. 80, no. 10 (May 20, 1958), p. 2587.

First Known Use

1958, in the meaning defined above

Time Traveler

The first known use of melatonin was in 1958

See more words from the same year

Cite this Entry

Style

“Melatonin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/melatonin. Accessed 21 Mar. 2023.

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Kids Definition

melatonin

noun

mel·a·to·nin ˌmel-ə-ˈtō-nən

: a hormone that is secreted by the pineal gland especially in response to darkness and has been linked to the regulation of bodily functions or activities (as sleep) that occur in approximately 24 hour cycles

Medical Definition

melatonin

noun

mel·a·to·nin ˌmel-ə-ˈtō-nən

: a vertebrate hormone C₁₃H₁₆N₂O₂ that is derived from serotonin, is secreted by the pineal gland especially in response to darkness, and has been linked to the regulation of circadian rhythms