If something hinders this process, like changing time zones or developing a sleep rhythm disorder, small amounts of synthetic melatonin, sold over-the-counter, may help you readjust to a normal sleep schedule.
Melatonin won't work for every case of insomnia or sleeping problems, though. "Your body has to be ready for sleep for melatonin to work," says David Rapoport, MD, medical director of the New York University Sleep Disorders Clinic. "So for those people who have insomnia because they just don't get sleepy—we call this hyperarousal—melatonin won't do them much good."
The following is from our A-Z Health Library:
What is melatonin?
Melatonin is a
hormone made by the
pineal gland 
, a small gland in the brain. Melatonin helps control your sleep
and wake cycles. Very small amounts of it are found in foods such as meats,
grains, fruits, and vegetables. You can also buy it as a
supplement.
What does natural melatonin do in the body?
Your body has its own internal clock that controls your natural cycle of sleeping and waking hours. In part, your body clock controls how much melatonin your body makes. Normally, melatonin levels begin to rise in the mid- to late evening, remain high for most of the night, and then drop in the early morning hours.
Light affects how much melatonin your body produces. During the shorter days of the winter months, your body may produce melatonin either earlier or later in the day than usual. This change can lead to symptoms of seasonal affective disorder (SAD), or winter depression.1
Natural melatonin levels slowly drop with age. Some older adults make very small amounts of it or none at all.
Why is melatonin used as a dietary supplement?
Melatonin supplements are sometimes used to treat jet lag or sleep problems (insomnia). Scientists are also looking at other good uses for melatonin, such as:
- Treating seasonal affective disorder (SAD).
- Helping to control sleep patterns for people who work night shifts.
- Preventing or reducing problems with sleeping and confusion after surgery.
- Reducing chronic cluster headaches.
It may be that melatonin, when taken as a supplement, can stop or slow the spread of cancer, make the immune system stronger, or slow down the aging process. But these areas need more research.
Melatonin is also being studied to see if it can be used to treat sleep problems in people who are blind.2 Since these people cannot see light, they may have sleep problems such as sleeping during the day and being awake at night.
Is taking a melatonin dietary supplement safe?
In most cases, melatonin supplements are safe in low doses for short-term and long-term use. But be sure to talk with your doctor about taking them.
Children and pregnant or nursing women should not take melatonin without talking to a doctor first.
Melatonin does have side effects. But they will go away when you stop taking the supplement. Side effects include:
- Sleepiness.
- Changes in blood vessels that may affect blood flow.
- Lower body temperature.
- Stomach problems.
- Headache.
- Morning grogginess.
- Vivid dreams.
If melatonin makes you feel drowsy, do not drive or operate machinery when you are taking it.
During health exams, tell your doctor if you are taking melatonin. And tell your doctor if you are having trouble sleeping (insomnia), since it may be related to a medical problem.
In adults, melatonin is taken in doses from 0.2 to 20.0 mg, based on the reason for its use. The right dose varies widely from one person to another. Talk to your doctor to learn the right dosage and to find out if melatonin is right for you.
Where can you find melatonin as a supplement?
You can buy melatonin supplements without a prescription at health food stores, drugstores, and online. Melatonin should only be taken in its man-made form. The form that comes from ground-up cow pineal glands is rarely used, since it may spread disease.
Last Updated: July 28, 2008 
