Insomnia Symptoms in Chinese Patients with Chronic Schizophrenia: Prevalence, Clinical Correlates and Relationship with Inflammation

Background: Sleep disturbances are common in patients with schizophrenia, with serious consequences. The purpose of this study was to investigate the prevalence and clinical correlates of insomnia symptoms, and to explore the relationship between insomnia and inflammatory markers in Chinese patients with chronic schizophrenia. Methods: A total of 328 inpatients with chronic schizophrenia were recruited. Insomnia Severity Index (ISI), Calgary Depression Scale for Schizophrenia (CDSS), and Positive and Negative Syndrome Scale (PANSS) were used to assess the severity of insomnia, depression, and psychotic symptoms. The plasma levels of several inflammatory markers (CRP, IL-6, and TNF-α) were measured.Results: The prevalence of insomnia symptoms in patients with schizophrenia was 38.4%. Depressive symptoms were significantly associated with insomnia symptoms (OR = 1.23, 95%CI: 1.13-1.33, P < 0.001). Higher CDSS score (beta = 0.55, t = 8.21, P < 0.001) and older age (beta = 0.06, t = 3.59, P < 0.001) were significantly associated with higher ISI score, while taking a single SGA (beta = -0.85, t = -1.99, P < 0.05) was independently associated with lower ISI score. There was no significant association between any inflammatory markers and insomnia or ISI score.Conclusions: Our results demonstrate that the prevalence of insomnia symptoms is high in Chinese inpatients with chronic schizophrenia. Some demographic and clinical variables, such as depressive symptoms and older age, are risk factors, while others are beneficial factor, such as taking atypical antipsychotic drug for insomnia in schizophrenia patients. No association has been found between insomnia symptoms and inflammation.