Serum inflammatory markers and total antioxidant capacity in relation to sleep outcome in the elderly

Sleep disturbance in the elderly has been linked to systemic inflammation and oxidative imbalance. However, most studies are cross-sectional and rarely evaluate inflammatory markers and a functional antioxidant summary alongside both subjective and objective sleep measures. We examine baseline and 12‑month within‑person co-variation between inflammatory markers, total antioxidant capacity (TAC), and sleep outcomes in the elderly. We conducted a 12‑month observational cohort to examine associations between serum inflammatory markers (C-reactive protein CRP, Interleukin-6 IL-6, Tumor necrosis factor-α TNF-α) and total antioxidant capacity (TAC) with sleep outcomes quality in elderly. Paired tests and multivariable linear regression were used to evaluate within-person change and cross-sectional associations, adjusting for prespecified covariates. Participants with Pittsburgh Sleep Quality Index (PSQI) ≥ 8 were offered Cognitive behavioral therapy for insomnia (CBT‑I) as usual care; treatment effects were not evaluated. Over the study period, inflammatory markers (CRP, IL-6, TNF-α) showed a modest decrease, while TAC slightly increased. Concurrently, actigraphy revealed a small rise in average sleep duration, and the PSQI improved. Regression analyses demonstrated that reductions in inflammatory markers and increases in antioxidant capacity were independently associated with improved sleep outcomes, while a composite index combining these biomarker changes correlated significantly with greater PSQI improvements after adjust for age, sex, and BMI. The study confirms that higher levels of inflammatory markers and lower levels of antioxidant are associated with decreased sleep quality. Moreover, improvements in sleep were associated with decreases in CRP, IL‑6, and TNF‑α and increases in TAC over 12 months. These findings support inflammation and antioxidant capacity as complementary correlates of sleep health and motivate future causal studies to test directionality and mechanisms.