Melatonin: nature's sleeping pill?

by Rick Alan

Melatonin Taking supplements of the hormone melatonin has been purported to relieve insomnia, but the evidence for its effectiveness is mixed. Should you try it?

Anyone whos had insomnia knows how frustrating it can be. There are a variety of prescription and over-the-counter sleep aids available, one of which is the hormone melatonin, sold in the form of a dietary supplement.

Although we often dont notice them, many of our bodily functions—including the rise and fall of blood pressure and changes in body temperature—run on a daily cycle called a circadian rhythm. Sleep also follows a circadian rhythm.

Melatonin is a naturally occurring hormone that plays an integral role in regulating sleep patterns; it is produced by a tiny, light-sensitive gland at the center of the brain known as the pineal gland.

During the day, light causes the retina of the eye to send continuous impulses to the pineal gland, shutting down the production of melatonin. As darkness falls and light impulses sent to the brain begin to decrease, the pineal gland begins to secrete melatonin, which induces sleep. These secretions continue throughout the night, until morning light begins to stimulate the retina to again start sending impulses to the brain, decreasing the secretion of melatonin until you wake up.

When this rhythmic cycle of melatonin secretion is thrown off, sleeping problems may result. The problem can be caused by defects in either direction. If melatonin production continues into the morning, or, in some cases, all day, drowsiness, sleepiness, or even depression can result. Usually, however, the problem occurs in the other direction. If insufficient amounts of melatonin are secreted early enough in the evening, its difficult to fall asleep. And if not enough melatonin is secreted during the night or the secretion ends too soon, you may get an inadequate amount of sleep.

Although sleep disturbances thought to be caused by low levels of melatonin can occur at any age, they becomes more frequent with age. Thats because children and teenagers produce melatonin in great quantity—one of the reasons why children tend to fall asleep so quickly and sleep so much. As we move into our 20s and 30s, production of melatonin tends to level off. And once we get to age 40, melatonin production starts to (and continues to) decline—one of the reasons why older people often have so much difficulty maintaining good sleep patterns.

It seems reasonable, then, that taking melatonin supplements would be a natural way to improve sleeping patterns. After all, if melatonin deficiency is causing the problem, shouldnt additional melatonin solve the problem?

Unfortunately, while melatonin may be helpful for some, especially people who generally dont have difficulty falling asleep, melatonin has been unreliable in consistently helping to improve sleep in people who regularly suffer from insomnia.

Scientific evidence regarding melatonins effectiveness is mixed. According to The American Pharmaceutical Association Practical Guide to Natural Medicines, "although there have been no large or long-term controlled trials on the subject, the data collected so far indicate that taking a very small amount of melatonin—a fraction of a milligram in some cases—can hasten sleep in insomniacs as well as people who do not normally have trouble sleeping."

One of the trials showed that when 0.3 to 1 milligram of melatonin was taken by healthy volunteers one to two hours before they usually went to sleep, it took them less time to fall asleep, to initiate a deeper sleep, and to experience rapid eye movement (REM) sleep. Moreover, they reported no drowsiness the following day.

Other studies of elderly people with insomnia and blind people with sleeping difficulties (many people who are blind suffer from chronic insomnia and/or daytime drowsiness since the daily cycle of light and darkness does not affect them in the same manner as it does sighted people) also found melatonin to be useful in promoting and maintaining sleep.

On the other hand, Dr. Gregg Jacobs, an insomnia specialist at the Sleep Disorder Center at Bostons Beth Israel Deaconess Medical Center and author of the book Say Goodnight To Insomnia,says that "there is little if any scientific evidence to support the claim that melatonin is effective for insomnia in young and middle-aged adults." He goes on to cite a 1997 survey by Consumer Reports that found that less than half of insomniacs who tried melatonin said it was helpful, and a 1996 National Institutes of Health review panel that urged skepticism about the use of melatonin. "It just doesnt seem to be consistent for [people with] chronic insomnia. Although there have been several studies published suggesting melatonin does improve sleep, the studies were done with normal sleepers, not insomniacs," says Dr. Jacobs.

The bottom line? Try melatonin with your doctors approval, but dont set your expectations too high. Supplements of between 0.3 and 6 milligrams taken approximately one half to a full hour before going to bed have been found to be effective. Since too much melatonin can result in drowsiness the following day, its best to start with a very low dosage and slowly increase it (up to 6 milligrams) until the desired effect is accomplished.

To date, no major health risks have been noted in people taking melatonin. No side effects have been found from taking small doses (0.3 to 3 milligrams), although some people have noted headache, drowsiness, and/or transient depression with larger doses. Let your physician know if youre taking melatonin, and take it in smaller doses (1.5 to 3 milligrams per day when needed).

Never take melatonin before driving or operating machinery. Women who are pregnant or nursing should not take melatonin, nor should anyone with epilepsy, diabetes, depression, kidney disease, or autoimmune disorders. And since young people generally produce large amounts of melatonin, no one under the age of 20 should take melatonin supplements.

Finally, there have been numerous other claims made about the benefits of taking high doses of melatonin to fight cancer, extend life expectancy, and act as a contraceptive. At present, some studies relating to these claims are being conducted, but no concrete scientific evidence demonstrating these positive effects has been found. Indeed, many experts fear that a powerful hormone like melatonin taken in high doses over a long period of time could, in fact, pose some potentially severe health risks. Accordingly, people should not take melatonin for any of these reasons at this point.