By Dr. Fred Hui

Of the many hot-topic health supplements available today, melatonin is one of the hottest. Discovered only four decades ago, research has discovered many uses for melatonin. Scientists are quite convinced that melatonin:

• Promotes going to sleep and thus helps people with insomnia;
• Combats jetlag and has special usefulness for athletes and travelers who cross many time zones in a day;
• Works as an antioxidant;
• Boosts the immune system of the human body;
• May prevent and/or treat cancer; and, most significantly
• Resets the body’s aging clock and turns back the ravages of time!

Production
Melatonin is produced in the body by the pineal gland (a tiny structure located at the base of the brain). The pineal gland secretes melatonin when it is dark; secretions are inhibited by perception of light. The blood level of melatonin is higher at night (highest at 1 to 2 am) and is lower during the day. A blind person may not coincide his levels with the day and night rhythm, since he or she is unable to perceive the difference between light and darkness.

Melatonin for sleep
A high level of melatonin induces sleep, and a low level coincides with wakefulness. Amongst humans, babies have the highest level and therefore sleep the most. Secretions from the pineal gland diminish with age and a sharp decline occurs around puberty. Middle-aged adults produce only half as much melatonin as children and supplements may work miracles for those with insomnia. Melatonin-induced sleep is natural—it does not cause you to awaken groggy, as is the case with usual sleeping pills—but you should not compare it with conventional sleeping. Melatonin is not very useful as an occasional instant sleeping pill, but it may start working after a few nights of intake when the “reservoir” of melatonin becomes progressively fuller.

Melatonin and jetlag
Melatonin also works for jetlag. It may rapidly reset the biological clock and almost totally prevent the symptoms of jetlag: loss of appetite; a distorted estimation of time, distance and space; irritability; gastrointestinal disturbances; disorientation; difficulty in concentrating; depression and sleep disorders. Many top athletes and commercial pilots take melatonin to reduce the negative symptoms of jetlag. It may be taken on the first evening in the new time zone. The dosage schedule, however, varies widely.

Role of melatonin in cancer
Studies have shown that melatonin slows the growth of cancer cells in a test tube. It has also been shown to enhance the effect of a hormone called Interleukin-2, used in the treatment of lung cancer, and tamoxifen, used for the treatment of breast cancer. Melatonin has been used to treat cancers of the intestine in combination with a hormone called IL-2.

Melatonin and free radicals
Free radicals are constantly being poured into our systems as byproducts of oxygen consumption (in our body). Free radicals damage our immune system and play a role in age-related degeneration of the body’s organs and tissues. Melatonin, like vitamins C and E, acts as an antioxidant and counteracts these free radicals. It also stimulates the main antioxidant enzyme of the brain, glutathione peroxidase.

Can melatonin prolong life?
Scientists are very much interested in knowing if melatonin can reset the biological clock to a youthful level, and thus prolong life. In experimental studies, it has been shown to prolong the lifespan of rats and mice by 20%. This could be due to its action as an immune modulator, a free-radical scavenger, an anti-cancer agent, a preserver of youthful circadian rhythm, and its possible role on other endocrine organs, especially the enhancement of growth hormones by the pituitary gland.

Are there any contraindications?
Yes. The following people should not take melatonin:

• Pregnant and nursing women—it is not yet known what effects melatonin has on babies;
• Healthy children—they already have plentiful levels of melatonin in their bodies; and
• Women who want to conceive—higher doses may induce a contraceptive effect.

Are there any side effects?
Melatonin has minimal side effects. It may cause drowsiness and slow reaction time if taken in bigger doses. In a clinical trial in the Netherlands, 75mg of melatonin was given to 1,400 women for up to four years, with no ill effects. No significant side effects have been reported to the FDA since melatonin became an over-counter-drug in the US. In Canada, it was just released to for purchase by the public as of the beginning of 2004.

Dosage
The usual dose is 3 mg, taken orally, any time in the evening. The dosage may be tailored upwards to 8 mg if sleep does not improve in one week, or downward if the user experiences a hangover (very rare). Some people take as little as half a milligram per night. Melatonin should be taken at night only.

References