1005 Improving Sleep Quality as a Mechanism for Alleviating Pain Severity: Evidence from a Three-Arm RCT of Psychological Treatments for Fibromyalgia

Abstract Introduction Fibromyalgia (FM) is characterized by widespread pain, fatigue, mood disturbance, and nonrestorative sleep. Although poor sleep is often viewed as a consequence of chronic pain, longitudinal and experimental studies show that sleep disturbances predispose individuals to chronic pain and exacerbate pain. Research also suggests that interventions that improve sleep quality may enhance pain reduction. The present study was a secondary analysis of a three-arm randomized controlled trial that compared emotional awareness and expression therapy (EAET), cognitive-behavioral therapy (CBT), and FM psychoeducation (FM-Ed) on sleep and pain outcomes. We sought to determine whether improving sleep could be a treatment mechanism by which EAET and CBT reduced FM pain. Methods A sample of 230 adults with FM (77.8% white, 93.9% female, aged M=49.1 yrs) were recruited from the community, completed baseline Pittsburgh Sleep Quality Index (PSQIT1) and Brief Pain Inventory (BPIT1), were randomized and received 8 weekly group sessions of EAET, CBT, or FM-Ed, and were then assessed on post-treatment outcomes (PSQIT2, BPIT2). The PRODCLIN method was used to test whether improving sleep quality (operationalized as PSQIT2-T1) mediated treatment effects of EAET/CBT on pain severity (BPIT2), compared to FM-Ed, controlling for BPIT1 and sociodemographics. Results Post-treatment, EAET produced significant improvements in sleep quality, d=-0.54,p<.001, and pain severity, d=-0.39,p<.01, relative to FM-Ed, whereas CBT showed significant improvements in only sleep quality, d=-0.53,p<.001, over FM-Ed. Mediation analyses indicated that improvements in sleep quality significantly mediated the treatment effect of both EAET (indirect effect=-0.107,95%CI[-0.21,-0.03]) and CBT (indirect effect=-0.124,95%CI[-0.23,-0.04]) models on post-treatment pain severity. In both therapies, patients who achieved clinically significant sleep-quality improvements (≥4-point decrease on the PSQI) showed substantial reductions in pain severity (EAET=32.6%, CBT=28.0%), while more modest pain reductions were observed in patients whose sleep improved only a little (< 4-point decrease; EAET=12.0%, CBT=5.5%). Conclusion These findings highlight sleep improvement as a promising treatment mechanism for alleviating FM pain. Integrating sleep-focused strategies into psychological pain interventions may enhance their effectiveness, with approaches that target both sleep and pain concurrently likely providing more comprehensive benefits for FM patients. Support (if any) This research was funded by the National Institute of Arthritis, Musculoskeletal, and Skin Diseases (Grant: AR057808, PI: MAL).