Association Between Glucocorticoid Exposure and Objective Sleep Architecture in Rheumatoid Arthritis: An Exploratory Pilot EEG Study

Objective: To explore the association of glucocorticoid (GC) exposure with objectively assessed sleep architecture in patients with rheumatoid arthritis (RA). Methods: A single-center exploratory pilot study involving 20 consecutive patients with RA (9 GC users and 11 non-users; mean age 64.9 years) was conducted. Using single-channel electroencephalography (EEG) and accelerometry, objective sleep architecture and autonomic balance were evaluated. Sleep parameters included wake after sleep onset (WASO), sleep stages, and delta EEG power during the first sleep cycle, while heart rate variability, expressed as low frequency/high frequency (LF/HF) ratio, was used as an index of autonomic balance. RA disease activity was evaluated using the Disease Activity Score in 28 joints based on C-reactive protein (DAS28-CRP). Associations between clinical variables and objective sleep parameters were evaluated using Spearman rank correlation analysis. Results: Disease activity, assessed by DAS28-CRP, did not differ significantly between GC users and non-users. Compared with non-users, GC users had longer WASO (p = 0.011), shorter non-rapid eye movement (NREM) stage N3 duration (p = 0.010), and lower delta power (p = 0.014) than non-users. A higher nighttime-to-daytime LF/HF ratio was also observed in GC users, although this difference did not reach statistical significance. Total sleep time, sleep latency, and sleep efficiency were comparable between the groups. WASO was positively correlated with age, GC use, and GC dose, whereas NREM stage N3 duration and delta power were negatively correlated with GC exposure. No significant associations were observed between age or sex and objective measures of deep sleep. Conclusions: Among patients with RA, GC exposure was associated with poorer sleep continuity and reduced deep sleep despite comparable disease activity. Given the small sample size of this exploratory single-center study, these findings should be interpreted cautiously. Larger longitudinal studies using objective sleep measures are warranted to confirm these associations.