1. age: 22-48 years old

2. gender: male, female

3. who got a depressive score above 20, were included in the depressed group

4. those who obtained a depressive score below 9, were chosen and they were included in the healthy control group.

5. the healthy control group to match to the depressed patients for education, social occasion, occupational and economical situation.

6. the depression disorder was confirmed on the basis of the DSM criteria

The Study of Serum Melatonin Rhythm Levels in Patients With Major Depressive Disorder