melatonin

[ mel-uh-toh-nin ]

noun

, Physiology.

1. a hormone secreted by the pineal gland in inverse proportion to the amount of light received by the retina, important in the regulation of biorhythms: in amphibians, it causes a lightening of the skin.

melatonin

/ ˌmɛləˈtəʊnɪn /

noun

1. the hormone-like secretion of the pineal gland, causing skin colour changes in some animals and thought to be involved in reproductive function

melatonin

/ mĕl′ə-tō′nĭn /

1. A hormone produced in the pineal gland that plays a role in regulating biological rhythms, including sleep and reproductive cycles. In many animals, melatonin also regulates the physiological effects that occur in response to seasonal changes, such as the growth of a winter coat of fur. Chemical formula: C 13 H 16 N 2 O 2 .

Word History and Origins

Origin of melatonin¹

Coined in 1958 by U.S. researcher Aaron B. Lerner and colleagues; from Greek mélā(s) “black” + tone + -in ²

Word History and Origins

Origin of melatonin¹

C20: probably from mela ( nocyte ) + ( sero ) tonin

A Closer Look

Melatonin, a natural hormone manufactured by the pineal gland in the brain, communicates information about light to different parts of the body. It helps regulate biological rhythms and plays an important role in the reproductive cycles of many animals. In humans it is best known for helping to regulate the body's circadian sleep-wake cycle. Melatonin production is affected by light exposure to the eyes; melatonin levels rise during the night and fall during the day, becoming almost undetectable. Though it does not actually induce sleep, melatonin can have sleep-promoting effects. Experiments have shown that at high doses melatonin lowers body temperature, decreases motor activity, and increases fatigue. Melatonin production starts falling after puberty, and it can virtually disappear in the elderly, a phenomenon which could help to explain why sleep disturbances are more prevalent among older adults. Marketed as a dietary supplement and touted as a cure-all for insomnia, jet lag, and even cancer and aging, the overall effects of melatonin on human health are still largely unknown.

Example Sentences

You can even factor melatonin supplements into your regimen.

From Washington Post

To know if the new LED could help people who want to sleep better, scientists will have to measure its effect on melatonin.

From Science News For Students

Plus, the LEDs in this and other smartphones still emit enough blue light to affect the body’s internal clock and melatonin production.

From Science News For Students

High levels of melatonin tell the body it’s time to go to sleep.

From Popular-Science

She cried, she played Wheel of Fortune on her phone, she put herself to sleep with melatonin.

From ProPublica

He or she can work with you to map out an individualized plan, which may entail taking the hormone melatonin.

From The Daily Beast

Once your serotonin levels are back up to normal, they can make enough melatonin so you can sleep better, says Dr. Rindfleisch.

From The Daily Beast

This helps us regulate our cortisol and melatonin levels for a proper wake and sleep cycle.

From The Daily Beast

One more thing, take it in the morning otherwise it can disrupt your sleep since vitamin D and melatonin are inversely related.

From The Daily Beast

Worse, disruption of melatonin can contribute to obesity and cardiovascular disease as well.

From The Daily Beast