Melatonin levels normally go up when it turns dark, and they are low during daylight hours. This hormone is also an antioxidant/free-radical scavenger that appears to slow the aging process. The production of melatonin is high in youth and declines steadily with age. Many signs of aging are associated with this loss of melatonin production, but cause and effect have not been proven. Large doses of melatonin have been administered to animals and humans without any known side effects.

Supplements of melatonin, taken at night, often help with insomnia and in overcoming symptoms of jet lag (for jet lag, it is taken near the bedtime in the new time zone for two or three days before departure and after arrival). Unlike most medications for insomnia, melatonin is not addictive. When it is used for insomnia, it does not leave you with any hangover or withdrawal symptoms. Some animal and human studies have shown benefits in reducing cancer and enhancing immune function. In animal studies, there is a clear increase in longevity (unfortunately, it is difficult to do longevity studies in humans). In humans, it has helped in treating depression and also in lowering the eye pressures in patients with glaucoma.

How to Take Melatonin
Melatonin is commonly available in 3-mg capsules or tablets, and the usual dose is 3-6 mg at bedtime. Sometimes higher doses are helpful for insomnia and depression. Some people seem to benefit from taking 10-15 mg of melatonin, without developing any apparent side effects. Larger doses are being studied for birth control because of melatonin's effect on sexual hormone balance.

Supplements of melatonin are almost all synthetically produced, but the synthetic molecules are identical to the natural human melatonin. There may be some brands on the market that contain actual animal pineal gland, but I do not recommend these. They are not as well standardized and they may contain impurities. Synthetic melatonin supplements are pure white, while the gland sources usually have some coloration.