Objective To investigate the difference of Wechsler's cognitive test and its influencing factors in first-episode depression patients with and without sleep disorder.Methods 156 patients with de-pression were divided into two groups according to their sleep conditions,including sleep disorder group(n=77)and non-sleep disorder group(n=79).Wechsler Intelligence Scale(WAIS)and Wechsler Memory Scale(WMS)were used to assess the cognitive function,while Hamilton Depression Scale(HAMD-17) were used to assess depressive symptoms.Results (1)Sleep disorders group had lower scores on verbal IQ (95.51±16.45),performance IQ(90.94±13.87),FIQ scores(92.48±15.49)than those in the non-sleep disorder group((105.59±15.20),(96.19±13.62),(101.20±14.70)respectively),the differences were statistically significant(P<0.05).Sleep disorder group had lower scores in immediate memory(10.47 ± 3.88),short-term memory(49.87±14.35)and memory quotient(87.90±18.25)than those in the non-sleep disorder group((11.86±3.47),(56.52±13.03),(97.27±18.76)respectively),the differences were statisti-cally significant(all P<0.05).(2)Multivariate linear regression analysis showed that education and age ex-plained 24% of variance in verbal IQ(F=21.258,P<0.01).Education,sleep disorder factors explained 12.9% of variation in performance IQ(F=9.825,P<0.01).Education,sleep disorder factors explained 22.3% of variance in total IQ(F=22.847,P<0.01).Education,age,sleep disorder factors explained 28.4%of variation in short-term memory(F=23.850,P<0.01).Education and age explained 20.4% of variation in immediate memory(F=18.10,P<0.01).Education and sleep disorder factors explained 21.9% of variation in memory quotient(F=26.162,P<0.01).Conclusion The intelligence and memory impairment in first-epi-sode depression patients with sleep disorders is more serious,and the education,sleep disorder and age are the most important factors.