Melatonin
Description
Melatonin is a hormone naturally produced by the pineal gland. It is formed from tryptophan following a series of enzymatic reactions.
Function
One of the most important functions of melatonin is its involvement in the regulation of the sleep-wake cycle. It also regulates the circadian rhythm of other functions such as digestive functions, body temperature and the release of other hormones, just to name a few. Melatonin also has powerful antioxidant properties. The release of melatonin is stimulated by darkness and its secretion starts at dusk reaching a peak between 2:00 and 4:00 am. The level of melatonin is higher in children and progressively decreases with age.
Melatonin is currently investigated for its effects on sleep-wake cycles, the immune system, cancers, the ageing process, cognitive impairment (memory and learning process), seasonal affective disorder, Alzheimer’s and Parkinson diseases.
Deficiency
No deficiency is described per se. This being said, because the level of melatonin progressively decreases with age, some researchers think that melatonin supplements should be given to all elderly people; however, this still needs to be demonstrated.
Toxicity
No toxicity is described although the effect of long term supplement intake is not known. Melatonin should be avoided in pregnancy or by women wishing to conceive. Possible interactions with anti-depressant drugs have been described. Consult your physician if you want to take melatonin supplements and are taking other drugs.
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Scientific References
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"Exogenous melatonin has acute sleepiness-inducing and temperature-lowering effects during 'biological daytime', and when suitably timed (it is most effective around dusk and dawn) it will shift the phase of the human circadian clock (sleep, endogenous melatonin, core body temperature, cortisol) to earlier (advance phase shift) or later (delay phase shift) times.".
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