Sleep and pain interference in individuals with chronic pain in mid- to late-life: The influence of negative and positive affect.

Poor sleep and chronic pain are known to be interrelated, but the influence of negative and positive affect on this relationship is not fully understood. The present study sought to examine whether negative and positive affect mediate the relationship between sleep and pain interference. Secondary data analysis from Midlife in the United States (MIDUS-III) was used to examine 948 individuals with chronic pain (mean age = 64.73 years). Sleep disturbance was conceptualized as the sum of self-reported difficulty with sleep-onset latency, wake after sleep onset, early morning awakening and daytime sleepiness, and total sleep time was assessed via self-reported sleep duration. Pain interference was operationalized as the sum of pain-related interference with general activity, relationships and enjoyment of life. Finally, items from the Positive and Negative Affect Schedule were used to measure affect. Mediation analyses revealed that sleep disturbance indirectly predicted pain interference via both negative affect (β = 0.15, confidence interval: 0.10, 0.21) and positive affect (β = 0.18, confidence interval: 0.12, 0.25). Similarly, negative (β = -0.003, confidence interval: -0.01, -0.001) and positive affect (β = -0.003, confidence interval: -0.01, -0.001) also mediated the effect between total sleep time and pain interference. This study highlights the unique role of negative and positive affect on pain interference for individuals with chronic pain in mid- to late-life. Additionally, findings suggest that holistic treatment approaches, which assess both sleep and affect in the context of chronic pain, may be beneficial.