Sleep disturbance is a common comorbidity of chronic pain. Inflammatory processes are dysregulated in sleep disturbance and also contribute to pain sensitivity. Thus, inflammation may play an important role in bidirectional associations between pain and sleep. Little is known about concurrent relationships among chronic pain, sleep, and inflammation. The aim of our study was to examine associations between sleep disturbance and circulating levels of the inflammatory cytokine, interleukin-6 (IL-6), in individuals with and without chronic low back pain.
Sex-matched and age-matched adults with chronic low back pain (CLBP; n=25) or without chronic pain (controls; n=25) completed measures of sleep quality in the past month and depressive symptoms in the past week, and provided a blood sample for IL-6. The next morning, participants reported their sleep quality the previous night and their current experience of morning pain.
Individuals with CLBP had more sleep disturbance than controls. Circulating IL-6 levels were similar for the 2 groups; however, in adults with CLBP, poorer sleep quality was associated with higher IL-6 levels, and both sleep and IL-6 related to pain reports. Unlike CLBP participants, controls showed normal, age-related increases in IL-6 levels, whereas sleep quality was unrelated to IL-6 levels. Depressive symptoms could not fully explain the observed associations.
Inflammatory processes may play a significant role in the cycles of pain and sleep disturbance. Clinical interventions that improve sleep and reduce concomitant inflammatory dysregulation hold promise for chronic pain management.