French philosopher and scientist René Descartes declared in the seventeenth century that the pineal gland was the "seat of the soul." He didn't know the half of it. The pea-sized gland in the brain produces melatonin, a hormone secreted most profusely as darkness falls, to help regulate the body's sleep cycle. If Descartes got on the World Wide Web and visited a melatonin home page or joined a melatonin discussion group, he'd learn that this hormone is all the rage. He'd also discover that, because his body appears to produce less melatonin as he ages, he should take continuous supplemental doses of this "magic potion," the "melatonin miracle." Melatonin can not only give him a good night's sleep or reset his biological clock and fix his jet lag, it may ward off depressive and panic disorders, the common cold, cancer, even aging. He can pick up a bottle of pills at the health-food store or from various Web purveyors. His physician might advise him not to take a neurologically and endocrinologically active substance manufactured without benefit of regulation, but maybe Descartes has melatonin madness.
In "Melatonin Madness," an article in the journal Cell, Steven M. Reppert and David R. Weaver ask, "Is all this excitement really justified, or is it just hype?" Reppert and Weaver are professor and associate professor of pediatrics, respectively, based at Massachusetts General Hospital's Laboratory of Developmental Chronobiology.
"Melatonin does have therapeutic potential," says Reppert, "but that potential is in the early stages of evaluation. The oversell has tainted the remarkable research progress made in the past five years." "Melatonin administered orally to humans has been used successfully to treat jet lag and some circadian-based sleep disorders," Reppert and Weaver write. Moreover, "there is good scientific evidence" that melatonin can induce sleep in humans, and a very low-level dose will do the trick. As to "the claim that the hormone can reverse aging," they write, "this assertion is scientifically unfounded and is based on the results of a seriously flawed study performed in mice.The antioxidant effect of melatonin has also been embellished, leading to claims that melatonin is a wonder drug useful for treating everything from AIDS to Alzheimer's disease." While melatonin does scavenge from the blood stream certain free radicals that attack cells, these antioxidant effects require melatonin concentrations a million times greater than any human would produce at any time. Says Reppert, "The long-term consequences of taking melatonin in such massive amounts are simply unknown."
