Where is melatonin produced

Evolutionarily, it dates back billions of years serving essential cellular processes with its antioxidant and free radical scavenging functions, and more recently as a key element in the regulation of circadian rhythms and the sleep-wake cycle. It is useful to think of our endogenous melatonin in 2 ways: 1 reactions occurring intracellularly that do not necessarily involve specific melatonin receptors and 2 the more familiar circadian role associated with regular changes in circulating melatonin and effects on melatonin receptors.

Although present in a variety of tissues, circulating melatonin is predominantly produced in the pineal gland under the control of the master circadian clock transcription-translation loops in the hypothalamic suprachiasmatic nucleus SCN , which is entrained by exposure to the light-dark cycle.

Melatonin production also can be suppressed by light exposure, so this can be a factor affecting the circulating levels and sleep patterns. Usually melatonin plateaus at a relatively high level throughout the night and then declines by morning. When the pineal gland produces melatonin, it is immediately released into the bloodstream and cerebrospinal fluid. Changing melatonin concentrations reinforce circadian activity in nearly all tissues and the changing duration of nighttime melatonin secretion reflects the time of year, especially important for seasonally breeding species.

The normally coordinated functioning of homeostatic and circadian processes promotes our nighttime sleep of about 8 hours and our daytime-evening wakefulness of about 16 hours. From late afternoon into the evening, the SCN-driven circadian system produces arousal that counters the homeostatic sleepiness that has accumulated since the morning awakening, thus allowing sustained functioning into the evening. Typically, we are the most alert in the early evening than any other time of the day or night.

With approaching bedtime, the rising melatonin agonist activity at the SCN melatonin receptors decreases the stimulation, leaving the homeostatic sleepiness unopposed, thus facilitating bedtime sleep onset.

It is notable that the melatonin action is not sedation, but rather a reduction in the evening circadian arousal. In everyday life, we think of melatonin as a widely available, fairly benign, and maybe helpful sleep aid product. In the United States, it is categorized as a dietary supplement, although in some countries it requires a prescription.

Unlike official over-the-counter OTC products, which are highly regulated composition, manufacturing, indications, labeling, and marketing , dietary supplements have little oversight. Studies analyzing consumer melatonin products have shown varying amounts of the compounds, as well as the presence of other unlabeled and sometimes surprising ingredients.

Does exogenous melatonin taken as a dietary supplement enhance sleep? Is it safe? There is a reasonable argument that taking evening melatonin might augment the natural process of reducing circadian arousal to help people fall asleep more quickly.

There are large variations in the amount of melatonin produced by individuals and these are not associated with any health problems. The main consequences of swallowing large amounts of melatonin are drowsiness and reduced core body temperature. Very large doses have effects on the performance of the human reproductive system. There is also evidence that very high concentrations of melatonin have an antioxidant effect, although the purpose of this has not yet been established.

About Contact Events News. Search Search. You and Your Hormones. Students Teachers Patients Browse. Human body. Home Hormones Melatonin. Melatonin Melatonin is mainly produced by the pineal gland and, although it appears not to be essential for human physiology, it is known to have a range of different effects when taken as a medication. Alternative names for melatonin N-acetylmethoxytryptamine pineal gland in the brain.

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