It has been called "the holy grail of sleep research." It's the ultimate jet-lag cure, some claim. It can reverse the effects of aging, revitalize your sex life, and ward off cancer, still others say. Need more? It may be the key to a new birth control pill, and it could be part of a new treatment for such diseases as Alzheimer's and Parkinson's. It's, the so-called "wonder drug." And though it's been available over-the-counter at health food stores for years, the remarkable substance-a hormone produced naturally by the pineal gland near the brain-has only recently become the hottest health product on the market. A recent Newsweek magazine cover story helped bring attention to, the subject of a small library's worth of books by researchers around the world who tout the hormone's fantastic properties. An army of biologists, endocrinologists, and neuroscientists have all hitched their wagons to Melatonin's star, each proposing dramatic and diverse claims and promising fabulous results. The latest is Dr. Russel J. Reiter, a professor at The University of Texas Health Science Center at San Antonio (UTHSCSA), perhaps the world's foremost authority on, and the co-author of the new book, Your Body's Natural Wonder Drug. Despite his book's title, Reiter, who has spent the better part of his life studying, takes exception to the hype surrounding the controversial hormone. "That's a little bit of publishing hyperbole," Reiter explains, discussing his book's title. "There's no such thing as a cure all or a silver bullet." At the core of the public's fascination with are some studies that have surfaced in recent years hinting that the hormone may be more than an effective sleeping pill. Melatonin is produced by a tiny organ in the brain known as the pineal gland, which plays a role in the sleep-wake cycle. Melatonin levels rise at night and drop during the day, and because its production drops off as people age, many consumers use the supplement to ward off insomnia and jet lag. In fact, Melatonin's role as a sleep-inducing agent is about the only thing researchers can agree on-and even that is subject to debate. In a recent article in The Medical Post, a Canadian medical journal, Dr. Gregory Brown, a researcher who, like Reiter, has spent decades studying, agrees that the hormone's ability to reset the body's biological clock may help thwart jet lag and restore sleep timing in shift workers. "But," he is quoted in the article, "whether it will help with chronic insomnia, problems where people wake in the middle of the night and so on, is less-well established." At least one book has made a quantum leap beyond Melatonin's recognized effects. In The Miracle, Drs. Walter Pierpaoli and William Regelson allege that may enhance sex, reverse the effects of aging, and fight diseases such as cancer. "That's bogus," says Reiter emphatically. "It was written in one book that it may slow down some of the signs of aging. The fact is, if you're 70 and you take it, you're still going to be 70." Rhonda Bone, manager of Vera's Health Foods in San Antonio, says that though has been on the shelves in her store for five years, sales of the tablets (which sell for $12.95 for a bottle of 60) have jumped markedly because of the recent publicity. "Most of the time people are looking for something to help them sleep," says Bone. "But in the last few weeks people have been coming in because they've heard about the other benefits on radio or seen it on TV. It's getting some new people into health stores." Bone herself began taking two years ago after returning from a convention. "I wanted to see if it would really work for jet lag," she says. "Now I'm convinced it helps you sleep better and I take it every night." Whether or not can or will relieve anything other than sleep disorders or jet lag is a point of contention among researchers. Reiter says that is simply a very good molecule that, in conjunction with vitamins such as E, may one day be an effective treatment against free radicals. Free radicals are by-products of the metabolism that damage to human cells. "We think it may be effective in the treatment of Alzheimer's and Parkinson's diseases because it's so good as an antioxidant -- it stimulates the immune system, and gets into the brain much faster than vitamin E," says Reiter. Foiling research into Melatonin's potential are pharmaceutical companies. Because is a hormone the body produces naturally, it can't be patented (though at least one scientist is pursuing a "use patent" to develop the drug). And since has been marketed for years as a food supplement alongside vitamins, there's been little interest among pharmaceutical firms for funding research. "That's been a real detriment," says Reiter. "It's a phenomenally good compound and there's no money going into research." Another concern is safety. Because isn't subject to the battery of tests the Food and Drug Administration imposes on other over-the-counter pills, some have questioned proper dosages and its long-term effects. In fact, no one knows the "right" dosage, though studies have found that as little of a fraction of a milligram can induce sleep. The same goes with Melatonin's long-term effects. One brand examined in a recent Consumer Reports study warned people suffering from diabetes, depression, leukemia, epilepsy, or autoimmune diseases, as well as pregnant or nursing women from taking the product without consulting a physician. Reiter says he's unaware of any negative studies, but warns potential users to take a conservative approach. "If you take it," he emphasizes, "have a reason for taking it, in the amounts you need. The tablets sold come in three milligrams. That's an incredibly small amount when you consider that we routinely take aspirin in 500 milligram dosages. It's less toxic than aspirin or ibuprofen, and safer than almost anything we eat. We shouldn't over scrutinize it." For Reiter, a professor of neuroendocrinology at UTHSCSA since 1971, the hype surrounding is at least bringing worldwide awareness to a subject that's been his life's work. Reiter began his research as an army captain assigned to study the effects of suspended hibernation in the early days of the space program. In the course of researching vitamin A and estrogen, Reiter and other biologists discovered and published their first report in 1965. By 1980, Reiter says, its usefulness as a sleep aid and in the treatment of jet lag became apparent. "In the last three years," he adds, "it's been shown to be this phenomenal antioxidant." So what's next for the wonder drug? Reiter reiterates that, which is easily reproduced synthetically, may play an important role in the treatment of clinical conditions of Alzheimer's and other free radical-related diseases such as Parkinson's and fetal alcohol syndrome. His new book also claims "good news" for autistic children, those with heart disease, HIV, and senior citizens. Elsewhere, the Bethesda, Maryland-based National Institute for Mental Health is launching a major study to determine Melatonin's effects on Seasonal Affective Disorder, or SAD, a severe form of the winter blues. Because is known to be important in coordinating seasonal rhythms in many types of animals-a connection Reiter's research confirmed in 1976-NIMH researchers believe abnormal secretion may impact patients with SAD. "The next five years are very important," Reiter says.