Sleep Problems are Associated With Chronic Pain Over and Above Mutual Associations With Depression and Catastrophizing.

INTRODUCTION Pain, mood problems, and sleeping difficulties are often comorbid and contribute to reduced physical function and quality of life for those with chronic pain. However, the way in which these factors interact is unclear. Until recently it was thought that the effect of sleep on pain and physical function was simply a result of its common association with mood problems. However, a growing body of research suggests that sleep may have a unique contribution. OBJECTIVES The aim of this study was to determine whether sleep disturbances were associated with pain and poor physical function independent of psychological distress in patients attending a tertiary pain medicine unit. MATERIALS AND METHODS 101 patients with chronic pain completed a set of questionnaires measuring pain, sleep, and mood, and also completed a selection of physical assessments conducted by a physiotherapist. RESULTS In total, 75.2% of participants had insomnia and 84.3% reported the presence of at least 1 sleep problem. Significant positive correlations with pain were detected for depression, catastrophizing, insomnia, short sleep duration, and poor sleep quality. Sleep duration had a significant independent association with pain after accounting for depression and catastrophizing. Sleep duration also had an independent association with physical function after accounting for pain and catastrophizing. CONCLUSIONS Given that sleep has an important and unique contribution to pain and physical function, it is important that sleep disturbances are addressed both in the assessment and treatment of chronic pain.