Melatonin: Nature's Sleeping Pill?
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 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, 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, it's 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.
As we move into our 20s and 30s, production of melatonin tends to level off. And once we reach age 40, melatonin production starts to (and continues to) decline. It has been theorized that this is one of the reasons why older people often have so much difficulty maintaining good sleep patterns.
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. While some studies have shown benefit, others have not.
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.
However, there are several positive studies in a variety of conditions, such as improving sleep in blind people, in people hospitalized in the ICU, and in people with various medical problems such as asthma or Parkinson's disease. More research is needed to straighten out the contradictions.
Other Uses of Melatonin
There is some evidence that melatonin may offer other benefits, including reducing anxiety, treating symptoms of tardive dyskinesia and cluster headaches. Melatonin may also help treat Seasonal Affective Disorder, which causes depression and many other symptoms in the dark winter months. In addition, there have been numerous other claims made about the benefits of taking high doses of melatonin, to fight cancer, extend life expectancy, and treat fibromyalgia. At present, some studies relating to these claims are being conducted, but no concrete scientific evidence demonstrating these latter effects has been found.
Should You Try It?
The bottom line? Try melatonin with your doctor's approval, but don't 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, it's 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 you're 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.
What about long-term use? Some experts fear that a powerful hormone like melatonin taken in high doses over a long period of time could, in fact, pose some potential health risks. Accordingly, people should not take melatonin consistently except under physician supervision.
American Academy of Family Physicians
National Institute of Mental Health
Canadian Family Physician
Canadian Mental Health Association
Melatonin. Familydoctor.org website. Available at: http://familydoctor.org/handouts/258.html.
National Institute of Mental Health. Properly Timed Light, Melatonin Lift Winter Depression by Syncing Rhythms. Available at: http://www.nimh.nih.gov/science-news/2006/properly-timed-light-melatonin-lift-winter-depression-by-syncing-rhythms.shtml.
Last reviewed January 2008 by Dianne Scheinberg MS, RD, LDN
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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