Sleep Characteristics in Adults With and Without Chronic Musculoskeletal Pain: The Role of Mental Distress and Pain Catastrophizing.

OBJECTIVES Sleep disturbance is associated with persistence and exacerbation of chronic pain. As this relationship seems to be bidirectional, factors underpinning sleep disturbance may prove valuable in multimodal rehabilitation approaches. The aim of this cross-sectional study was to examine the impact of psychological symptoms on subjective and objective sleep measures in patients with chronic musculoskeletal pain (CMP) as compared to healthy controls (HC). METHODS Sleep was assessed by self-report questionnaires, actigraphy and polysomnography recordings in 56 patients (75.0% female; Mage=41.7▒y, SD=10.8▒y) with CMP and compared to 53 matched HC (71.7% female; Mage=41.8▒y, SD=10.7). Mental distress (HSCL) and pain catastrophizing (PCS) were tested as predictors of objective and subjective sleep measures in multiple regression models, and their indirect effects were tested in bootstrapped mediation models. RESULTS The sleep data revealed substantially more subjective sleep disturbance (Hedge's g: 1.32-1.47, P<0.001), moderately worse sleep efficiency in the actigraphy measures (Hedges g: 0.5-0.6, P<0.01) and less polysomnography measured slow wave sleep (SWS) (Hedges g: 0.43, P<0.05) in patients as compared to controls. HSCL was strongly associated with the self-reported measures Insomnia Severity Index (ISI) and Pittsburgh Sleep Quality Index (PSQI). HSCL also partially explained the pain (CMP / HC) to sleep association, but HSCL was not associated with any of the objective sleep measures. More pain catastrophizing was related to less SWS. DISCUSSION The differences in subjective and objective sleep measures indicate that they probe different aspects of sleep functioning in patients with musculoskeletal pain, and their combined application may be valuable in clinical practice. Self-reported sleep disturbance seems to overlap with affective dimensions reflected by the HSCL- questionnaire.