The hormone melatonin plays a role in your natural sleep-wake cycle. Natural levels of melatonin in the blood are highest at night. Some research suggests that melatonin supplements might be helpful in treating sleep disorders, such as delayed sleep phase, and providing some relief from insomnia and jet lag.

Melatonin is generally safe for short-term use. Unlike with many sleep medications, with melatonin you are unlikely to become dependent, have a diminished response after repeated use (habituation), or experience a hangover effect.

The most common melatonin side effects include:

• Headache
• Dizziness
• Nausea
• Drowsiness

Other, less common melatonin side effects might include short-lasting feelings of depression, mild tremor, mild anxiety, abdominal cramps, irritability, reduced alertness, confusion or disorientation, and abnormally low blood pressure (hypotension). Because melatonin can cause daytime drowsiness, don't drive or use machinery within five hours of taking the supplement.

In addition, melatonin supplements can interact with various medications, including:

• Anticoagulants and anti-platelet drugs
• Anticonvulsants
• Contraceptive drugs
• Diabetes medications
• Medications that suppress the immune system (immunosuppressants)

If you're considering taking melatonin supplements, check with your doctor first — especially if you have any health conditions. He or she can help you determine if melatonin is right for you.