Sleep disturbances and psychotic experiences along the continuum : the correlates and potential mediators

Abstract

Sleep disturbances are distressing complaints commonly reported in individuals with psychotic disorders. Whilst increasing evidence suggests the continuum of psychosis, there has been a paucity of data examining poor sleep quality and specific sleep disturbances in relation to dimensional psychotic experiences and quality of life across the continuum of psychosis. The objectives of this dissertation were to investigate the correlates of sleep problems along the psychosis continuum and to explore the psychological factors mediating the associations between sleep problems and dimensional psychotic experiences. This dissertation consisted of two cross-sectional studies. In Study 1, 76 outpatients with schizophrenia spectrum disorders were recruited from a regional hospital in Hong Kong. Sleep disturbances, dimensional psychotic experiences, health-related quality of life and global functioning were assessed with self-reported questionnaires. The findings of Study 1 indicated that poor sleepers had a significantly higher degree of paranoia, hallucination and cognitive disorganization. They were also more likely to report poorer quality of life. The association between poor sleep quality and decreased quality of life remained significant after controlling for potential demographic and clinical confounders. In Study 2, 878 healthy young adults were recruited from two universities in Hong Kong. Participants completed the online questionnaires measuring sleep disturbances, dimensional psychotic experiences, cognitive bias, negative affect and quality of life. The findings of Study 2 suggested that individuals with sleep problems tended to report increased psychotic experiences, cognitive bias, negative affect and decreased quality of life. The associations between sleep quality and distinct psychotic experiences were found to be mediated by negative affect and cognitive bias. Taken together, the present findings underscored the importance of timely assessing and addressing sleep problems and the need of sleep-focused treatment both for the patients with psychotic disorders and individuals with subclinical psychotic-like experiences.