What Is Melatonin and How Does It Work?
| The Research on Melatonin for Sleep
| Other Uses of Melatonin
| What Are the Precautions?
| Should You Try It?
Taking supplements of the hormone
has been purported to relieve insomnia, but the evidence for its effectiveness is mixed. Should you try it?
Anyone who's 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.
What Is Melatonin and How Does It Work?
Although we often don't 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 start sending impulses to the brain again, decreasing the secretion of melatonin until you wake up.
When this rhythmic cycle of melatonin secretion is thrown off, such as when traveling across multiple time zones, 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 may result. Usually, however, the problem occurs in the other direction. If insufficient amounts of melatonin are secreted early enough in the evening, it is 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.
The Research on Melatonin for Sleep
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, shouldn't additional melatonin solve the problem? Most (though not all) studies have found benefits with melatonin for treating jet lag. However, melatonin has not shown consistent benefits for other types of insomnia.
Mixed results have been seen especially with the use of melatonin for treating insomnia related to shift work, or the typical insomnia that occurs with age. Not only have many studies failed to find melatonin helpful, those studies with positive results found widely varying benefits. For example, some studies found a decreased time to falling asleep, but no change in sleep throughout the night, while others found the reverse. These differences have not followed dose or type of melatonin in any obvious way, making them somewhat suspect. More research is needed to straighten out the contradictions.
Melatonin has also been studied as a potential treatment for people with sleep problems related to certain conditions, like diabetes, head injury, and Alzheimer's disease. Overall, though, these studies have been small, so more research is needed to come to a definitive conclusion about melatonin's effect on sleep.
What Are the Precautions?
Melatonin may cause drowsiness, decreased mental attention, and balance problems, which can last for 2-6 hours. Because of these effects, never take melatonin before driving or operating machinery. Some experts recommend against taking melatonin if you have a serious condition, like depression, schizophrenia, or an autoimmune disease. In addition, it is not known what the long-term health risks are for taking this hormone over an extended period of time.
Safe dosages have not been set for children, women who are pregnant or nursing, or people with liver or kidney disease.
Should You Try It?
The bottom line? You may try melatonin with your doctor's approval, but do not set your expectations too high. Supplements of between 1-5 milligrams taken about 30-60 minutes before going to bed is an acceptable dose. Since too much melatonin may result in drowsiness the following day, it is best to start with a very low dosage.
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Buscemi N, Vandermeer B, Hooton N, et al. The efficacy and safety of exogenous melatonin for primary sleep disorders. A meta-analysis. J Gen Intern Med. 2006;20:1151-1158.
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Melatonin. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/healthLibrary/. Updated August 2011. Accessed December 5, 2011.
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Last reviewed December 2011 by Brian Randall, MD
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