Psychotic-like experiences (PLEs) are prevalent occurrences deemed comparable with the symptoms of psychosis, but not sufficiently severe to warrant a diagnosis upon clinical presentation. Their presence is associated with several adverse clinical outcomes: the onset of various common mental health disorders (e.g. anxiety, mood, substance abuse), poorer functioning, non-remission and relapse. Sleep and circadian rhythm disruption (SCRD) is observed in 30-80% of patients with psychosis. The omnipotence of SCRD across all phases of the disorder (including the prodromal, acute, chronic and residual phases) raises the question as to whether SCRD may directly contribute to the development of psychosis. Assuming that PLEs are along the same continuum to developing psychosis, a logical next step to further disentangle the sleep-psychosis relationship is to examine whether SCRD relates to the experience of PLEs and whether this relationship is bi-directional. This thesis begins by examining the core predictions made by a continuum model of understanding psychosis and how specific parameters of sleep may influence PLEs. A smaller high-definition cross-sectional study follows, examining biological underpinnings (electroencephalography (EEG), electrocardiography (ECG), endogenous melatonin rhythms and actigraphy) of a complaint of poor sleep and their relation to the occurrence of PLEs. We then refocus on which parameters of sleep are most integral to the sleep-PLE relationship and close with an investigation of how Hypothalamic Pituitary Adrenal (HPA) axis activity may further our knowledge of this relationship. The findings of this thesis demonstrate specificity in the parameters of sleep shown to impact certain PLEs. The importance of objective sleep and biologically driven measures in this line of research are underscored, with group differences in EEG, ECG and melatonin. This thesis also highlights dissociative symptomatology as a candidate mediator for the sleep-psychosis relationship, and emphasises the ties between paranoia and negative affect. Finally, this thesis also illuminates the challenges of examining the relationship between sleep and PLEs in isolation, and suggests that they must be considered within the broader framework of co-existing mental health problems.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:735910 |
| Date | January 2017 |
| Creators | Cosgrave, Jan |
| Contributors | van Heugten-van der Kloet, Dalena ; Wulff, Katharina |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://ora.ox.ac.uk/objects/uuid:0e871ab6-6bbd-48f2-99fd-94ef2df95937 |
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