Holistic hormone: melatonin is more than a sleep aid

Because it only comes out at night, melatonin is sometimes referred to as the "Dracula" of hormones. Sunset triggers heightened melatonin secretion from the pineal gland; these levels subside with sunrise, thereby regulating periods of sleep and wakefulness.

When this biological clock, known as circadian rhythm, is disrupted, sleeping can be difficult, and supplemental melatonin may help improve sleeping patterns. Other credits to melatonin's name include effects in anti-aging, brain health, cancer and obesity.

Sleep

Melatonin supplements tend to be used mainly for improving sleep, which is a concern in the United States. According to the National Sleep Foundation's 2002 "Sleep in America" poll (available online at www.sleepfoundation.org), more than half of American adults have difficulty falling asleep or staying asleep at least a few times a week.

Melatonin supplements may be of use for certain insomnias and circadian rhythm sleep disorders, as reported in the November 2004 issue of the journal Sleep Medicine. Specifically, melatonin supplements taken at the same time each night improve sleep in East-bound travelers, according to the January 2004 Journal of Applied Physiology. Additional research published in September 2004 in Sleep showed improved sleep in 40 healthy men who took melatonin supplements.

In addition to improving sleep in healthy subjects, melatonin may offer benefits for insomniacs since this group is known to produce low levels of melatonin, according to the December 2002 issue of the journal Psychiatry Research. Melatonin supplements at doses of 5 milligrams per day (mg/d) proved beneficial to children with chronic insomnia, according to a study presented in the November 2003 Journal of the American Academy of Child & Adolescent Psychiatry.

The same dosage, however, did not improve sleep in subjects with age-related sleep disorders, as reported in the March 2003 issue of Age and Ageing. Interestingly enough, however, elderly subjects participating in a Hawaiian study experienced improvements in sleep quality with a lower dosage of 1 mg/d.

Brain Health

The Hawaiian study, reported in the July-August 2004 American Journal of Geriatric Psychiatry, also showed that melatonin supplements helped cognitive function. These results led to the conclusion that melatonin may be therapeutic for treating age-related cognitive decline.

Melatonin treatment may also help to improve symptoms of Alzheimer's disease, according to a study published in the August 2003 Journal of Pineal Research. Melatonin injections protected against oxidative damage to brain tissue that was exacerbated by aluminum in an animal model of Alzheimer's disease.

Cancer

Melatonin's antioxidant properties may also lend it to cancer therapy, according to scientists from the University of Texas Health Science Center in San Antonio. Their animal research, published in the October 2000 International Journal of Cancer, showed a protective antioxidant effect when melatonin was administered concurrently with a known carcinogen.

Aging

As in cancer therapy, staving off free radical damage is important in anti-aging medicine, which may make melatonin useful for the elderly, especially since natural levels of melatonin are known to decline with advancing age.

"[B]ecause melatonin is a potent free radical scavenger, its deficiency may result in reduced antioxidant protection in the elderly, which may have significance not only for aging per se but also may contribute to the incidence or severity of some age-related diseases," writes Michal Karasek, MD, PhD, of the Medical University of Lodz, Poland, in the November 2004 issue of the journal Experimental Gerontology.

"Although melatonin cannot be recognized as a 'rejuvenating' agent, some of its actions may be beneficial for the aging process," Karasek says. "Administration of melatonin may improve temporal organization in advanced age."

Obesity

Some in the scientific community have suggested, based on animal models, that melatonin plays a role in preventing the development of obesity. According to research in the March 2004 issue of the Journal of Physiology and Biochemistry, melatonin helps regulate seasonal body weight and energy balance.

Animal research representing the Western diet was presented in the December 2003 issue of Endocrinology. When administered 1 hour before lights out, melatonin treatment decreased body weight gain and feed efficiency by half over the course of the 3-week study.

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