Related topics: sleep

Researchers devise a new way to plot circadian clock

(Phys.org)—Everyone has an internal clock, that mysterious process which controls sleeping and hunger patterns, but now researchers are finding out that because the internal clock also controls metabolism, it would be helpful ...

To Arctic animals, time of day really doesn't matter

In the far northern reaches of the Arctic, day versus night often doesn't mean a whole lot. During parts of the year, the sun does not set; at other times, it's just the opposite. A new study reported online on March 11th ...

Commercial-scale biomanufactured melatonin is here

For the first time, large amounts of melatonin are being made by bacteria. In industrial sized fermentation vats, harmless strains of engineered E. coli bacteria are feeding on glucose and churning out melatonin, the hormone ...

Scientists discover how animals measure time of year to reproduce

Animals need to measure the time of year so that they can anticipate and adapt to the arrival of a new season to align reproduction, as well as other vital functions critical for survival. A new study, conducted at the University ...

Melatonin, biological clock keep singing fish on time

In the 1980s, people living on houseboats in the San Francisco Bay were puzzled by a droning hum of unknown origin that started abruptly in the late evening and stopped suddenly in the morning.

Agronomists save tomatoes from toxic aluminum with melatonin

RUDN University agronomists and colleagues from China and Iran have helped tomatoes cope with the toxic effect of aluminum in acidic soils with the help of melatonin. This hormone contributes to nitric oxide production, blocking ...

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Melatonin

Melatonin i/ˌmɛləˈtoʊnɪn/, also known chemically as N-acetyl-5-methoxytryptamine, is a naturally occurring compound found in animals, plants, and microbes. In animals, circulating levels of the hormone melatonin vary in a daily cycle, thereby allowing the entrainment of the circadian rhythms of several biological functions.

Many biological effects of melatonin are produced through activation of melatonin receptors, while others are due to its role as a pervasive and powerful antioxidant, with a particular role in the protection of nuclear and mitochondrial DNA.

In mammals, melatonin is secreted into the blood by the pineal gland in the brain. Known as the "hormone of darkness," it is secreted in darkness in both day-active (diurnal) and night-active (nocturnal) animals.

It may also be produced by a variety of peripheral cells such as bone marrow cells, lymphocytes, and epithelial cells. Usually, the melatonin concentration in these cells is much higher than that found in the blood, but it does not seem to be regulated by the photoperiod.

Research has shown that when bird chicks ingest melatonin-rich plant feed, such as rice, the melatonin binds to melatonin receptors in their brains. No food has been found to elevate plasma melatonin levels in humans.

Products containing melatonin have been available over-the-counter as dietary supplements in the United States since the mid-1990s. In many other countries, the over-the-counter sale of this neurohormone is not permitted or requires a prescription, and the U.S. Postal Service lists unapproved melatonin preparations among items prohibited by Germany.

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