Sleep disturbances and the experience of pain : a multi-methodological approach

Abstract

Poor sleep and pain conditions present a major public health challenge due to their pervasive impact on well-being. Using a mix of experimental and observational methodologies, this thesis assesses sleep disruptions and its potential associations with the experience of pain. Chapter 4 comprises two experimental studies in healthy young adults (n = 57; n = 118) revealing that impairment in central pain inhibitory processes (conditioned pain modulation response) may be associated with self- reported sleep disruptions. The studies also support the validity of the conditioned pain modulation response as a physiological marker of pain inhibition. Chapter 5 presented a quasi-experimental study comparing chronic pain groups (Fibromyalgia n = 9; Chronic Back Pain n = 8) with healthy controls (n = 9) across range of self-reported and objective sleep and pain-related parameters. Findings revealed differences in patterns of self-reported sleep but not objective sleep between the two chronic pain conditions compared with healthy controls. The study also provided some extension of the findings from Chapter 4 by exploring the associations of objective sleep disturbance with less efficient pain inhibitory processes. To expand on these findings, the thesis adopted an epidemiological approach to explore the long-term interrelationship between sleep and pain-related outcomes in the general population. A systematic literature review (Chapter 6) of 16 longitudinal studies involving 61,000 participants consolidated evidence that changes in sleep are associated with several dimensions of the pain experience (risk of developing a pain condition, elevations in levels of inflammatory markers, and a decline in self-reported physical health status). Finally, Chapter 7 presents an analysis of a sample of the UK population and revealed the association between four-year changes in different insomnia symptom (sleep onset latency, awakenings, and daytime sleepiness) and perceived physical and psychological well-being in the general population (n = 30,594) and a subgroup with arthritis (n = 4,300). Overall, the findings from this thesis provide support for the associations of sleep disturbances with the processes underlying and shaping the experience of pain. The thesis highlights future research and beneficial interventions aimed at improving sleep and addressing associated pain-related health outcomes