Variations in Sleep Architecture among Different Subtypes of Schizophrenia: A Cross-sectional Study

Abstract

Introduction: Schizophrenia is a severe mental disorder characterised by positive symptoms such as delusions and hallucinations, as well as negative symptoms including anhedonia, asociality, avolition, and affective blunting. It may also be associated with cognitive deficits. Sleep disturbances are commonly encountered in schizophrenia, and there may be variations in sleep patterns among its different subtypes. These differences in sleep patterns could have prognostic implications for the various subtypes of schizophrenia. Effective management of sleep disturbances could contribute to the recovery and wellbeing of individuals diagnosed with schizophrenia. Aim: To compare the differences in sleep architecture between the various subtypes of schizophrenia and to compare them with socio-demographically matched healthy volunteers. Materials and Methods: A cross-sectional study was conducted at the Institute of Psychiatry-Centre of Excellence, Kolkata, West Bengal, India over a duration of one year (May 2016 to June 2017). The study included 60 medication-naïve patients diagnosed with schizophrenia according to International Classification of Diseases (ICD)-10 criteria, and a control group of 30 demographically matched healthy volunteers. All study participants were aged between 18 and 60 years and free from any co-morbid illnesses. Patients with schizophrenia were further classified into four groups based on the ICD-10 subtypes: paranoid, hebephrenic, catatonic, and undifferentiated. Overnight polysomnography was performed to assess sleep parameters, including total record time, total sleep time, sleep onset latency, Rapid Eye Movement (REM), sleep latency, sleep efficiency, durations of Total Non Rapid Eye Movement (NREM) Sleep, Total REM sleep, and the different phases of NREM sleep. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) version 20.0. Analysis of Variance (ANOVA), Chi-square, and t-test were used as applicable, with a p-value <0.05 considered statistically significant. Results: The results showed a decrease in sleep efficiency, total sleep time, and shorter duration of mean N1, N2, and N3 sleep in schizophrenia patients compared to the control group. There was a significant difference in N3 sleep duration, reduced duration of total NREM and REM sleep, reduced REM latency, increased sleep onset latency, and the number of awakenings during sleep in schizophrenia patients. Statistically significant differences (p-values <0.05) were also noted in some sleep parameters among the various subtypes of schizophrenia. The paranoid subtype had the shortest REM latency, while the catatonic subtype had the longest. The hebephrenic subtype had the lowest percentage of REM sleep and sleep efficiency, while the catatonic subtype had the highest. The duration of Slow Wave Sleep (SWS) was lowest in the undifferentiated subtype and highest in the catatonic subtype. Conclusion: This study reveals significant differences in sleep patterns between patients with schizophrenia and the control group, as well as among the various subtypes of schizophrenia. These distinctions provide insight into the relationship between schizophrenia subtypes, sleep irregularities, and clinical consequences. Further investigation is necessary to explore differences in sleep architecture among the various subtypes of schizophrenia and yield clinically meaningful results.