Insomnia symptoms predict systemic inflammation in women, but not in men with inflammatory bowel disease

Insomnia has been suggested as a potential modulator of systemic inflammation. However, few studies have examined the longitudinal association between insomnia and inflammation as well as the role of sex differences, despite accumulating evidence of the vulnerability of women to immune consequences of disturbed sleep. In this study, we tested the association between self-reported insomnia symptoms and serum C-reactive protein, a marker of systemic inflammation, at 1-year follow-up, in 54 outpatients with inflammatory bowel disease (52.81 ± 16.09, 40.7% women). Insomnia symptoms were measured using the Insomnia Severity Index. After controlling for baseline inflammation and health variables, longitudinal moderated regression analysis showed that baseline insomnia symptoms predicted C-reactive protein levels at follow-up in women (β = 0.416, p = 0.014), but not in men (β = -0.179, p = 0.212). Results were not influenced by sex differences in insomnia severity or C-reactive protein levels. This study suggests insomnia symptoms may partially influence systemic inflammation in women with inflammatory bowel disease. Sex-specific psychological, immune and neuroendocrine pathways linking sleep to inflammation should be further elucidated.