0436 Effect of sleep on the relationship between pain related disability and neural correlates of pain processing in adults with fibromyalgia and insomnia

Abstract Introduction Up to 80% of adults with fibromyalgia experience insomnia. While sleep and pain are known to be associated, sleep's role in the association between pain related disability and neural correlates of pain processing is unknown. We evaluated whether sleep moderates the association between brain activity in response to painful stimuli and pain related disability in adults with fibromyalgia and insomnia (FMI). Methods Twenty-nine adults with FMI (Mage=57.2, SD=13.1) wore Actiwatch 2s over 14 days, completed the Pain Disability Index (PDI), and underwent fMRI using a quantitative sensory testing (QST) protocol involving thermal stimuli. Twelve brain regions with significant activation changes to QST (identified previously, PMID34310276) were included as dependent variables, PDI score as independent variable and actigraphic sleep variables (Sleep Onset Latency (SOL), Total Sleep Time (TST), Sleep Efficiency (%SE)) as moderators in the analysis. For moderation at significance levels of p<0.05 (and trends at p<0.1), significance of simple slopes at high (1 SD above), average and low (1 SD below) sleep levels were examined. Results %SE moderated the relationship between right cingulate gyrus (rCG) activity and PDI score (B=0.0009, SE=0.0003, p=.016, R^2=0.22). At lower values of %SE (but not at average or higher levels), there was a negative association between rCG activity and PDI score (B=-0.0166, SE=0.0064, p=0.016). Moderating impact of SOL (B=-0.0002, SE=0.0001, p=.05, R^2=0.14) and TST (B=0.0002, SE=0.0001, p=.06, R^2=0.15) trended towards significance. [MCS1] PDI and rCG activity showed negative associations at highest levels of SOL, while PDI and right inferior frontal gyrus activity showed positive associations at highest levels of TST. Conclusion Since the rCG is involved in gating, integration and classification of pain signals, decreased activation in rCG could reflect reduced modulation of pain processing in the region. Preliminary results indicate that at lower levels of sleep efficiency, this decrease in modulation of pain processing is associated with greater perceptions of disability related to pain. Further studies in larger samples are warranted to understand the causal effects, if any, of sleep on pain related disability and the neural correlates of pain processing. Support (If Any) NIAMS-R01AR055160/S1; PI-McCrae