Multi-level inflammatory profiling reveals a cytokine signature associated with night-shift work exposure in female healthcare workers

Night-shift work is associated with circadian disruption and altered immune regulation, although the biological pathways underlying these interrelations remain incompletely characterized. A cross-sectional study of 243 female healthcare workers (147 night-shift workers, NSW; 96 day-shift workers, DSW) was conducted, to assess circulating cytokines (IL-6, IL-8, IL-18, TNF-α, IFN-γ), leukocyte-derived inflammatory indices (NLR, MLR, NMR, PLR, SII), and inflammatory network structure. NSW showed higher plasma cytokines, including TNF-α (7.76 vs. 6.51 pg/mL), IL-6 (1.72 vs. 1.40 pg/mL), IL-18 (204 vs. 172 pg/mL), IFN-γ (0.77 vs. 0.60 pg/mL), and IL-8 (3.88 vs. 3.55 pg/mL; all p < 0.05), with increased composite cytokine Z-score (0.95 vs. − 0.19, p < 0.0001). Leukocyte-derived inflammatory indices did not differ between groups. Multivariable analyses showed that the association between night-shift work and elevated cytokine levels remained directionally consistent after adjustment for age, BMI, menopausal status, smoking, alcohol consumption, physical activity, and sleep quality, with IFN-γ showing a significant adjusted association. Principal component analysis and hierarchical clustering identified distinct cytokine patterns, including TNF-α–IL-8–IL-18 and IL-6–IFN-γ modules. Correlation analyses revealed differences in the coupling between cytokine and hematological inflammatory indices between NSW and DSW. Among long-term night-shift workers, higher IL-6, IL-18, and TNF-α levels suggested a duration-related association with inflammatory profiles. Overall, night-shift work was associated with a coordinated low-grade cytokine signature, supporting the potential role of circulating cytokine profiling as an exploratory indicator of biological perturbation related to circadian disruption. Future longitudinal studies are required to clarify temporal and causal relationships.