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

Examples of melatonin in a Sentence

Recent Examples on the Web

That guessing game isn’t great when too much melatonin can lead to fatigue, dizziness, and confusion, among other wack side effects. —Ali Finney, SELF, 19 Apr. 2024

Those who experience discomfort relief from CBD and melatonin are also likely to experience better sleep, if only indirectly. —Medterra, Discover Magazine, 3 Apr. 2024

For some, relying on melatonin is key while others opt for a more natural approach. —Clare Mulroy, USA TODAY, 15 Mar. 2024

Similarly, exposure to sunlight in the morning stops melatonin production and bumps up the wake-up hormone cortisol. —Adria Greenhauff, Better Homes & Gardens, 8 Mar. 2024

That means timing—and lighting—are key to melatonin’s success. —Carly Weeks, TIME, 10 Apr. 2024

How to fall asleep faster and get better sleep with your bedtime routine Light Management: Dim or turn off lights 30 minutes before bed to signal your body to wind down and prepare for sleep, especially bright lights and blue light from screens which can disrupt melatonin production. —Maryal Miller Carter, USA TODAY, 25 Mar. 2024

But Lehman countered that the conversation involving Xanax was from a different time period and that the parents actually discussed giving him melatonin. —Gina Kaufman, Detroit Free Press, 8 Mar. 2024

Documents said police detained Harris on Jan. 5 and brought her to the department headquarters, where Harris admitted to bottle feeding her infant daughter Nyquil and melatonin before propping her in an upward position on the mattress and then placing her 17-month-old daughter in a playpen. —The Arizona Republic, 23 Feb. 2024

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

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