Sex differences in prevalence and clinical correlates of insomnia in Chinese patients with chronic schizophrenia

ObjectiveIt is generally recognized that there are sex differences in many aspects of schizophrenia. The main purpose of this study was to investigate the sex differences in the prevalence and clinical correlates of insomnia in patients with chronic schizophrenia.MethodsA total of 957 patients who met the DSM-IV diagnostic criteria for schizophrenia were recruited in this cross-sectional study (male/female = 630/327). Demographic, clinical, and insomnia data were collected using self-reported questionnaires. Fasting blood samples were collected to evaluate the status of blood lipids. Psychopathological symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS).ResultsThe prevalence rate of insomnia in female patients with schizophrenia was significantly higher than that in male patients (17.3% for males and 26.3% for females; χ2 = 10.74, p = 0.001). Regression analysis showed that in male patients, insomnia was independently associated with severe PANSS positive symptoms, severe PANSS depressive factor, and high levels of low-density lipoprotein levels, while in female patients, insomnia was associated with low education level, high PANSS depressive factor, and high levels of apolipoprotein B levels.ConclusionThis study illustrates that insomnia is more frequent in female than male schizophrenia patients, and that there are differences in the clinical correlates of insomnia by sex, suggesting that sex differences should be considered in prevention and treatment strategies for coexisting insomnia in schizophrenia patients.