Investigating change in cognitive and psychosocial functioning, subjective-objective sleep discrepancy, and an oxidative stress marker after group cognitive behavioural therapy for insomnia

Abstract

Insomnia disorder is a debilitating sleep disorder that impacts nearly 10% of Canadian adults. Cognitive Behavioural Therapy for insomnia (CBT-I) is a psychological treatment that targets cognitions and behaviours to improve sleep outcomes. CBT-I has been shown to be an effective treatment for insomnia symptoms; however, little is known about the cognitive and physiological underpinnings of the treatment response. This thesis examines correlates of cognitive, clinical, and biological markers of change across group CBT-I treatment. Specifically, we evaluated: (1) objective and subjective cognitive and psychosocial functioning, (2) discrepancies between objective and subjective measures of sleep, and (3) the relationship between a biological marker of stress and sleep parameters. The first study in this thesis investigated how objective and self-report measures of cognitive functioning, and psychosocial functioning changed across CBT-I. Findings illustrated that changes in self-report cognitive ability and psychosocial functioning were related to the improvements in insomnia symptom severity across treatment. The second study investigated the discrepancy between objectively measured sleep with actigraphy and self-reported sleep variables. Findings showed that the mismatch between objective and subjective sleep parameters decreased early on during the implementation of CBT-I. Additionally, improvement of clinical symptoms was related to a decrease in sleep discrepancies across treatment. In the third study, we examined if there was a relationship between a biological marker of oxidative stress across CBT-I. Results showed that following CBT-I, the biological marker was related to both objective sleep parameters and self-reported symptom improvement. Overall, this thesis demonstrates that in our well-characterized sample of adults with insomnia disorder, group CBT-I was associated with significant post-group changes in cognitive, clinical, and biological factors. This has important implications for the factors that may influence an individual’s treatment response to CBT-I, and thus lead to improvements in tailoring treatments to optimize outcomes for treatment of insomnia disorder.