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 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. But 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
health food stores, drugstores, and mail-order catalogs and on the Internet.
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.
