Cognitive characteristics of sleep and related factors in patients with schizophrenia comorbid with insomnia

Abstract

Objective To explore cognitive characteristics of sleep and analyze its influencing factors in patients with schizophrenia comorbid insomnia. Methods 61 patients with schizophrenia comorbid with insomnia, 62 patients with primary insomnia and 64 normal sleepers were recruited according to DSM-IV.The subjects in the three groups were measured by Dysfunctional Beliefs and Attitudes about Sleep Scale(DBAS)and Pittsburgh Sleep Quality Index(PSQI). Patients with schizophrenia were also measured by the Positive And Negative Symptom Scale(PANSS). Results The day function factor of PQSI for the schizophrenic patients(1.72±0.92) was significantly higher than that for the primary insomniacs(1.32±0.99) (P<0.05). The time to fall asleep factor of PQSI for the primary insomniacs (2.45±0.71) was significantly higher than that in the patients with schizophrenia (2.11±0.97). In addition to the false beliefs about improving sleep factor, the total and all factor scores of DBAS for the normal sleepers(79.44±10.53) were higher than that in schizophrenic group(68.26±11.76) and primary insomnia group(67.85±11.39)(all P<0.01). The expectations on sleep factor(β=-0.425, P=0.009)and the attitudes towards sleep medications factor(β=-0.239, P=0.048)were the influencing factors on sleep quality in schizophrenic patients comorbid with insomnia.The estimation of the consequences of insomnia(β=-0.279, P=0.001), predictive and control of sleep(β=-0.291, P=0.017)as well as age factors(β=0.078, P=0.020)were the influencing factors on in primary insomnia patients. Conclusion Patients with schizophrenia comorbid with insomnia and patients with primary insomnia have more distorted cognitions towards sleep, and their cognitions can greatly affect the quality of sleep. Key words: Schizophrenia; Insomnia; Beliefs and attitudes