Understanding Underlying Processes in Bipolar Disorder: Relationships between Circadian and Social Rhythm Stability, Appraisal Style and Mood.

Banks, Faye Danielle (2014) Understanding Underlying Processes in Bipolar Disorder: Relationships between Circadian and Social Rhythm Stability, Appraisal Style and Mood. PhD thesis, Lancaster University.

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Abstract

Disturbances in both circadian rhythms, such as the sleep-wake cycle, and social rhythms (i. e. daily routines) are well documented in bipolar disorder during mood episodes and periods of wellness. Despite this, current understanding of the nature of the relationship between rhythm instability and mood in bipolar disorder is relatively limited. Multilevel cognitive models of bipolar disorder suggest that internal appraisal styles may influence the impact of circadian rhythm disruption upon mood (Jones, 2001). The current research therefore aimed to explore relationships between circadian and social rhythm instability, internal appraisal style, and mood in euthymic individuals with bipolar disorder, individuals at behavioural high-risk and non-clinical controls. To investigate the extent to which internal appraisal styles play a unique role in bipolar disorder, individuals with fibromyalgia were also examined due to the similarly chronic nature of the two conditions. In the first phase of the research, participants completed an online survey, providing a broad impression of the cross-sectional relationships between rhythm instability, appraisal style and mood in a large sample (n=706). In the second phase, a smaller sample (n= 134) took part in a seven day experience sampling and actigraphy study, enabling exploration of concurrent and prospective relationships between rhythm instability, appraisal style and mood in everyday life. Bipolar participants exhibited high levels of objective and self-reported circadian rhythm instability, and also demonstrated a tendency to form negative, internal appraisals of experiences at the state and trait level. For the most part, hypothesized associations between rhythm instability and mood in the bipolar sample were not supported, contradicting Jones' (2001) model of bipolar disorder. Although mood states were significantly related to internal appraisal styles in the bipolar group, such appraisals did not demonstrate a moderating effect. The implications of the findings for theory and practice are discussed.