MUC2 and insomnia measurement: Insomnia not only reduces the gut’s antioxidant capacity, anti-inflammatory cytokine levels, mucin 2 (MUC2), and tight junction protein expression but also increases the levels of pro-inflammatory cytokines, leading to intestinal mucosal damage and increased barrier permeability (Gao et al., 2019; Li L. et al., 2023).