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Melatonin is secreted by the pineal gland, a pea-sized
entity located near the base of the brain. The pineal gland helps regulate the
hypothalamus gland and influences the functioning of the thyroid, thymus, pancreas and
adrenal glands. Melatonin is produced from the neurotransmitter serotonin.
Melatonin has many functions, including working as an
antioxidant and helping to regulate circadian rhythms (the body's biological clock which
regulates the sleep-wake cycles). It also has a positive influence on the immune system,
and it may act as a prophylaxis against osteoporosis, as well as an effective adjunct in
the fight against certain types of cancers.
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The metabolic pathway by which melatonin is produced
involves the neurotransmitter serotonin, a by-product of tryptophan, which is currently
unavailable for over-the-counter sale in the US. Tryptophan is the least abundant of
essential amino acids in normal diets, so it is likely that some individuals will have a
deficiency. This imbalance directly effects the ability to experience a restful
sleep, and could be positively effected by melatonin supplementation.
Melatonin also has applications in the
prevention of jet-lag. Dr. Arendt, at the University of Surrey in England, observed that
melatonin helped to re-synchronize the circadian rhythms of subjects flying through eight
time zones (San Francisco to London). Those subjects who took melatonin 3 days before the
flight, on the day of their departure and four days upon their return did not note any
appreciable jet-lag.
Melatonin produces a substance called arginine vasotocin, which inhibits
cortisol, a stress hormone produced by the adrenal glands. Insomniacs tend to have high
nighttime levels of this agitating hormone, so inhibition of this hormone is another way
melatonin promotes sleep. And the suppression of cortisol through the release of arginine
vasotocin also bolsters the immune system. Through the suppression of cortisol, it helps
to prevent the deterioration of lymphatic tissue, which is an integral part of the immune
system.
Research has demonstrated melatonin's immune enhancing potential
when administered to mice whose immune systems were challenged by either corticosteroids
or a highly toxic virus (encephalomyocarditis) . Most of the mice who were pre-treated
with melatonin showed a markedly higher survival rate than those who were not. Melatonin's
immunoprotective capabilities could lend themselves well to conditions of psychogenic or
environmental stress.
Additionally, melatonin may help prevent osteoporosis.
There is evidence to suggest that menopause is associated with a substantial decline in
melatonin because of impaired pineal functions due to calcification. During the early
stages of menopause, the decline in melatonin production seems to be a contributing factor
in the development of postmenopausal osteoporosis. Animal data indicates that melatonin is
an integral component in calcium homeostasis, through its stimulatory effect on the
pituitary and parathyroid glands - which inhibit calcitonin release and prostaglandin
synthesis. Therefore, measuring the levels of melatonin in early menopause could indicate
an impending osteoporotic condition, and taking melatonin could normalize levels and/or
serve as a prophylaxis against osteoporosis.
Many diseases, including artherosclerosis, multiple sclerosis, muscular
dystrophy, Parkinson's disease, emphysema, cataracts and autoimmune disorders, are
directly related to free radicals (molecules or portions there of which contain one or
more impaired electrons) that damage cells and organs. Among free radicals, the hydroxyl
(OH2) oxygen-centered radical appears to be the most deleterious. Melatonin,
through both in vivo and in vitro testing, has been demonstrated to be more effective than
glutathione in scavenging this reactive molecule. In vivo tests utilizing safrole
(a potent carcinogen from sassafras oil, that is known to damage DNA because of its
ability to produce large numbers of oxygen-centered radicals) demonstrated a significant
reduction in damaged hepatic DNA when compared to animals who were not pretreated with
melatonin. In vitro, hydrogen peroxide exposed to ultraviolet light formed 6x less
hydroxyl radicals when quenched by melatonin than by glutathione.
Melatonin also helps to prevent the proliferation of cancer cells.
Studies show melatonin has a protective effect against breast cancer, and patients with
brain metastases who were pretreated with melatonin also significantly improved their
survival time, compared to those who were treated with steroids and anticonvulsant agents.
However, it was observed that the inhibition was immediately reversed when its
administration was discontinued.
Melatonin has been studied for the past three decades and has been
administered at doses as high as 300mg a day without any adverse effects. It may cause
increased grogginess upon arising when used for sleep disorders, but this is a temporary
effect and can be prevented through regulation of the dose. Melatonin should only
be used by children or adolescents under the advice of a physician. To prevent
any disturbances in the circadian rhythms, melatonin should not be taken during the day,
but only before retiring. Used in this way, melatonin can, at the very least, contribute
to a good night's sleep, which itself promotes good health!
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