Melatonin

Overview

What is melatonin?

Melatonin is a hormone produced in the pineal gland, a small gland in the brain, that helps regulate sleep and wake cycles. Very small amounts of melatonin are found in foods such as meats, grains, fruits, and vegetables. It is also available as a dietary supplement, though it has no known nutritional value.

What does natural melatonin do in the body?

Your body has its own internal clock that helps regulate your natural cycle of sleeping and waking hours (or circadian rhythm) in part by controlling the production of melatonin. Normally, melatonin levels begin to rise in the mid- to late evening, remain high for most of the night, and then decline in the early morning hours.

Natural melatonin production is partly affected by light. During the shorter days of the winter months, melatonin production may start earlier or, more often, later. This change can lead to symptoms of seasonal affective disorder (SAD), or winter depression.¹

Natural melatonin levels decline gradually with age. Some older adults produce very small amounts of melatonin or none at all.

Why is melatonin used as a dietary supplement?

Melatonin dietary supplements are sometimes used to treat jet lag or sleep problems (insomnia). Scientists are also looking at other possible effective uses for melatonin, including:

• Treating seasonal affective disorder (SAD).
• Helping regulate sleep for people who work evenings or nights.
• Preventing or reducing problems with sleeping or confusion after surgery.
• Reducing the side effects of some antipsychotic medications used to treat schizophrenia.
• Reducing or preventing chronic cluster headaches.

It has been suggested that melatonin, when taken as a supplement, may stop or delay the spread of cancer, strengthen the immune system, or slow the aging process. However, these areas need further research.

Melatonin is also being studied for the treatment of sleep problems in blind people.² People who are blind with no perception of light, can have sleep problems such as sleeping during the day and being awake at night.

Is taking a melatonin dietary supplement safe?

Melatonin dietary supplements are generally safe in low doses for short-term and long-term use. Be sure to discuss melatonin use with your health professional.

Children and pregnant or nursing women should not take melatonin dietary supplements without a health professional's approval.

Do not drive or operate machinery when taking melatonin if it causes drowsiness.

The main side effect for most people from taking melatonin is sleepiness, which goes away when you stop taking it. Other reversible side effects may include:

• Changes in blood vessels that may affect blood flow.
• Lowering of the body's temperature (hypothermia).
• Stomach problems.
• Headache.
• Morning grogginess.
• Vivid dreams.

During health examinations, tell your health professional if you are taking melatonin dietary supplements. Your health professional should also be aware if you are having difficulty sleeping, since it may be related to a medical condition. For more information, see the topic Insomnia.

In adults, melatonin is taken in different dosages from 0.2 to 20.0 mg, depending on the reason for using the supplement. The recommended dose is typically 0.5 mg. The appropriate dosage of melatonin varies widely from one person to another. If you have difficulty getting to sleep or staying asleep, your health professional can help determine the proper dosage and whether melatonin is right for you.

Where do I find melatonin as a dietary supplement?

Melatonin dietary supplements are available without a prescription from some health food stores and pharmacies. Melatonin should only be taken in its synthetic (man-made) form. The biological form, made from ground-up cow pineal glands, is rarely used because it may transmit disease.

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Author:	Douglas Dana Sabra L. Katz-Wise	Last Updated: October 6, 2006
Medical Review:	Adam Husney, MD - Family Medicine Tom Bailey, MD - Family Medicine Alfred Lewy, MD, PhD - Neurology, Psychiatry
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