Abstract
BACKGROUND: Sleep disturbances are prevalent in major depressive disorder (MDD). Emerging evidence suggests a bidirectional relationship between inflammation and sleep disturbances, but the role of peripheral inflammatory markers in subjective sleep quality in treatment-resistant depression (TRD) remains unclear. METHODS: 34 MDD patients (20 TRD and 14 non-TRD) and 34 healthy controls were enrolled. Participants underwent clinical assessments, including the Hamilton Rating Scale for Depression and Pittsburgh Sleep Quality Index (PSQI). Serum levels of inflammatory markers, including soluble interleukin-2 receptor (sIL-2R), soluble interleukin-6 receptor, soluble tumor necrosis factor-α receptor type 1 (sTNF-αR1), monocyte chemoattractant protein-1, and C-reactive protein, were measured. General linear models were used to assess associations between inflammatory markers and subjective sleep quality, adjusting for relevant covariates. RESULTS: Patients with MDD scored higher in PSQI than healthy subjects. Higher serum levels of sTNF-αR1 were associated with longer sleep latency across the TRD and non-TRD groups. Elevated serum sIL-2R levels correlated with poorer overall sleep quality among patients with MDD. CONCLUSIONS: These findings underscored the importance of considering inflammatory pathways in understanding sleep disturbances in depression. Longitudinal studies are needed to elucidate causal relationships and inform potential therapeutic interventions targeting both inflammation and sleep in MDD.