What Is the Recommended Dosage?
The appropriate dose can vary enormously from person to person, and successful results have been achieved with dosages ranging from .1 mg (100 mcg) to 200 mg (200,000 mcg). "In controlled clinical studies researchers have found that as little as a tenth of a milligram (100 mcg) makes dozing off easier, whatever the time of day." Start off small (e.g. less than half of a milligram) each night before bed-time, and work your way to larger doses if needed. http://www.bodybuilding.com/fun/drsquat8.htm
There is currently no recommended dose for melatonin supplements. Different people will have different responses to its effects. Lower doses appear to work better in people who are especially sensitive. Higher doses may cause anxiety and irritability.The best approach for any condition is to begin with very low doses of melatonin. Keep the dose close to the amount that our bodies normally produce (< 0.3 mg per day). You should only use the lowest amount possible to achieve the desired effect. Your doctor can help you determine the most appropriate dose for your situation, including how to increase the amount, if needed. http://umm.edu/health/medical/altmed/supplement/melatonin
and http://www.vanderbilt.edu/AnS/psychology/health_psychology/melatonin.htm