The role of sleep and circadian rhythms in bipolar disorder

Thesis

The aim of this thesis was to investigate the multifaceted role of sleep, and, to a lesser extent, circadian rhythms in bipolar disorder (BD). In Chapter 3 we highlight the adverse sleep profile of BD when compared to two demographically homogeneous groups of people with major depression and health controls (n=1,072 each group). Although the sleep profile of BD and major depression were similar, people with BD showed increased insomnia symptoms, later chronotype, shorter sleep duration, increased need for sleep and greater dissatisfaction with sleep when compared to healthy controls. In Chapter 4, we sought to compare the sleep, rest-activity, mental health and cognitive functioning of BD high-risk offspring (n=11) to low-risk participants (n=21). Although all effects were in the direction we predicted, due to limitations in recruitment, none of these differences was statistically significant. In Chapter 5 we examine the effectiveness of behavioural and psychosocial interventions in BD that target sleep and circadian rhythms. The only modality with enough data to meta-analyse was the effect of bright therapy in depression, revealing a moderate-to- large improvement. Overall, the evidence base for the effectiveness of these interventions was limited, due to the lack of sleep and circadian outcomes, small samples and varied treatment protocols. Finally, in Chapter 6 we present findings from a mixed-methods, within-groups pilot trial of a digital cognitive behavioural therapy for insomnia, for people with BD-II (n=22). Our quantitative results show that the treatment is feasible, acceptable and potentially effective in improving insomnia, depression, anxiety, cognitive complaints, mental wellbeing and socio-occupational functioning both at post-treatment and at 3-month follow up. Our qualitative data emphasise the ubiquitousness and negative impact of sleep and circadian disruptions in BD, and the interest for relevant treatments. Overall, participants enjoyed the intervention, but highlighted the lack of therapeutic focus on excessive sleepiness alongside insomnia.

Authors: Bisdounis, L

• DOI: 10.5287/ora-kovx7qqww
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: bipolar disorder; sleep; activity; mood disorders; digital interventions; depression; circadian rhythms; affective disorders
• Subjects: Affective disorders; Bipolar disorder; Psychiatry; Circadian rhythms; Sleep