Objective To understand the differences in sleep quality and coping style of patients with double depression and major depression.Methods Taking DSM- IV- TR as the diagnostic criteria and DSM- Ⅳ Axis I Disorders- Patient Edition(SCID- I / P) as the diagnostic tools,totally 399 samples with depression disorder in epidemiological survey of mental illnesses in Hebei Province were grouped as double depression of 56 cases depression combined with dysthymia and major depression(with no mood disorder) of 343 cases...