Exploring the association between hallucinations, sleep, and cognitive control

Punton, Georgia (2024) Exploring the association between hallucinations, sleep, and cognitive control. Doctoral thesis, Northumbria University.

Text (Doctoral thesis) punton.georgia_phd(17036186).pdf - Submitted Version Restricted to Repository staff only until 22 August 2024. Download (2MB) | Request a copy

Abstract

Sleep has long been associated with mental health and wellbeing. Good sleep health is associated with indicators of good health, while dysfunctional sleep is a risk factor for, and consequence of, poor health outcomes and psychopathological symptoms. Hallucinations (perceptions of sensory input despite the absence of a stimulus) have been linked to poor sleep health in the general population and clinical groups (e.g., individuals with schizophrenia), and evidence tentatively suggests that cognitive control may play a role within this association. This thesis explored the relationship between sleep health, hallucinatory experiences and cognitive control. A narrative literature review identified cognitive control mechanisms common to cognitive models of hallucinations and processes affected by dysfunctional sleep, including inhibition, working memory, thought control, and emotion regulation. Two online studies then showed that sleep health is associated with hallucinatory experiences in the general population, partially mediated by thought control ability. Following this, an experimental paradigm demonstrated that sleep deprivation impairs the cognitive control process of intentional inhibition. Finally, a mixed methods study with non-clinical voice-hearers (NCVHs) revealed no difference to non-voice hearing controls on measures of sleep health or cognitive control, but did find that NCVHs use more cognitive reappraisal strategies. Their experience with voices involves a voice-hearing process, defined by periods of dysregulation, acceptance, and growth, illustrated by dynamic factors such as sleep health and perceived control. Together, these findings highlight potential discontinuity in models of hallucinations (in contrast to ‘continuum’ models), whereby sleep health and cognitive control present differently in NCVHs to other groups of hallucinators. Control over intrusive thoughts is associated with sleep health, and important in the presentation of hallucinatory experiences in the general population, while NCVHs may rely more on adaptive emotion regulation due to a constructive history with voices and developed coping strategies. The uniqueness of phenomenological narratives in NCVHs raises questions of the generalisability of such research findings to other populations.

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