IL-8 levels partially account for the indirect relationship between alcohol use disorder and global sleep quality in a cross-sectional study

Study Objectives Sleep disturbance is common in alcohol use disorder (AUD). Inflammation may play a role in the relationship between alcohol use and sleep disturbance. Interleukin-8 (IL-8), a pro-inflammatory chemokine, may be implicated in this relationship. Therefore, this study investigated the role of IL-8 in the relationship between AUD and sleep disturbance. Methods Sixty-two individuals with AUD (35 M/27F) and sixty-four controls (33 M/31F) completed the Pittsburgh Sleep Quality Index (PSQI), a self-report questionnaire assessing past-month sleep quality and disturbances and provided blood samples to assess IL-8 levels. Univariate ANCOVAs compared groups on PSQI global scores and IL-8 levels. An indirect cross-sectional association analysis tested if diagnostic group and PSQI global scores were indirectly associated via IL-8 levels. Results Individuals with AUD had higher PSQI global scores (F = 11.08, p = 0.001), indicating worse sleep, and higher IL-8 levels (F = 7.35, p = 0.008) compared to controls. AUD diagnosis was associated with higher IL-8 levels (a = 0.129, p = 0.008), and higher IL-8 levels were associated with worse PSQI scores (b = 3.157, p = 0.012). A partial indirect association effect was found where AUD diagnosis influenced PSQI scores through IL-8 levels (ab = 0.407, 95% CI = (0.062,0.905)); the direct effect of group on PSQI scores remained significant (c’ = 1.864, p = 0.005). Conclusions Results suggest that AUD diagnosis is associated with worse sleep, partially through an association with greater IL-8 levels. Identifying a role for IL-8 as a link between AUD and sleep disturbance will need to be tested longitudinal studies. If replicated, IL-8 inhibition may offer a novel treatment target for those with AUD and comorbid sleep disorders. This paper is part of the Sleep and Circadian Mechanisms in Mental Health Collection.