<p>Sleep disturbances are prevalent among patients with rheumatic diseases, yet the key drivers of sleep impairment across diagnostically heterogeneous, multinational populations remain poorly characterized. This study evaluated sleep quality and its independent association with patient-reported symptom burden in adults with rheumatic diseases.&#xa0;A cross-sectional online survey of patients was conducted in 772 adults with confirmed or suspected rheumatic disease from 28 countries, following STROBE reporting guidelines. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI; Cronbach's α = 0.81) and patient-reported symptom burden using the Routine Assessment of Patient Index Data 3 (RAPID3; Cronbach's α = 0.91). Multivariable linear and logistic regression models identified independent predictors of sleep quality, adjusting for age, sex, geographic region, disease group, number of diagnoses, and sleep medication use.&#xa0;The mean global PSQI score was 11.3 ± 4.4; 89.7% of participants had poor sleep quality (PSQI &gt; 5). RAPID3 category was the strongest independent predictor of PSQI scores: patients with high symptom burden scored 5.69 points higher than those near remission (B = 5.69, 95% CI 4.58–6.79). In multivariable logistic regression, patients with high symptom burden had 12.69-fold higher adjusted odds of poor sleep (95% CI 5.64–29.28). Sleep medication use was independently associated with worse sleep quality (B = 2.41, 95% CI 1.87–2.95; adjusted OR 2.63, 95% CI 1.42–5.13). The model explained 31.5% of variance in PSQI scores (adjusted R2 = 0.315). Disease group was not independently associated with PSQI scores after adjustment.&#xa0;Poor sleep quality is highly prevalent in rheumatic diseases and is independently associated with patient-reported symptom burden and sleep medication use, rather than with the specific diagnosis. Systematic sleep assessment is warranted across all rheumatic conditions, regardless of underlying diagnosis.</p>