8289120 How does night work-induced circadian disruption influence low-grade inflammation?

<h3>Objective</h3> Night work disrupts circadian rhythms by misaligning the sleep–wake cycle with the solar day and has been classified as probably carcinogenic to humans by the International Agency for Research on Cancer (IARC). Increased inflammation is a proposed mechanism linking night work–induced circadian disruption to cancer; however, most supporting evidence comes from experimental rodent studies. This study aims to investigate the effect of night work–related circadian disruption on low-grade inflammation, measured by C-reactive protein (CRP) levels, in a female human population. Specifically, we examine acute and chronic effects, reversibility, and cumulative exposure to night work on CRP. <h3>Material and Methods</h3> We used baseline data from the 1001 nights-cohort, which includes 1,075 women employed in Danish hospitals. Participants were eligible for inclusion in the analyses if they provided a blood sample for CRP measurement of CRP-concentration and had complete data on key variables, including age, anthropometric measures, self-reported health, and recent infections (n = 960). Night work exposure was assessed via self-reported current work schedule, night work intensity, number of consecutive night shifts, time since the last night shift, and number of night shifts in the previous week. We used linear regression to analyze associations between night work and log-transformed CRP concentrations. <h3>Results</h3> In preliminary age-adjusted models, CRP concentrations were 57% higher in permanent night workers compared with permanent day workers (95% CI: 11%–121%), and 38% higher compared with rotating night shift workers (95% CI: 1%–63%). <h3>Conclusion</h3> This study adds to the limited evidence on the relationship between night work–induced circadian disruption and low-grade inflammation in humans. By improving our understanding of how night work influences inflammatory markers, these findings may offer insights into its broader health implications, including cancer risk. <h3>Funding</h3> The present study was funded by the Danish Working Environment Research Fund.