Dyssomnic disorders (DD) associated with juvenile rheumatoid arthritis (JRA) are some of the most common conditions that are difficult to endure and that lead to deconditioning. This study aimed to assess prevalence and structure of DD, their relationship with clinical picture peculiarities and contribution to deterioration of the quality of lives of JRA patients. At the 1st stage, we assessed prevalence of DD in a continuous sample of JRA patients and healthy children aged 8–16 years. At the 2nd stage, we assessed DD structure, features associated with gender and age, connections to the key clinical characteristics of JRA and quality of life of the patients. In the context of the study, we used the SDSC sleep quality scale, the PedsQL 4.0 quality of life model, and the Ritchie index. DD develop in JRA patients 3.3 times more often than in healthy children (in 178 (72.3%) and 93 (22.2%) children, respectively). The DD registered were sleep initiation and maintenance disorders (54 cases, 22.0%), respiratory disorders (32 cases, 13.0%), sleep-to-wakefulness transition disorders (31 cases, 12.6%), excessive sleepiness disorders (38 cases, 15.4%), combinations thereof (23, 9.3%). Girls had sleep initiation and maintenance disorders more pronounced (p = 0.003), boys were more prone to excessive sleepiness (p = 0.008). The severity of DD increases with patients' age (r = 0.69; p = 0.001) and JRA onset age (r = 0.71; p = 0.001); they are also more severe in polyarticular JRA patients (r = 0.32; p = 0.048). We have clarified the relationship between DD and indicators of inflammatory (r = 0.56; p = 0.001) and Ritchie indices (r = 0.44; p = 0.005), duration of morning stiffness (r = 0.49; p = 0.029). The proven connection between DD and JRA entails the need for routine checks for DD in such patients, and, when discovered, DD should call for personalized therapeutic and diagnostic approach rather than be regarded as one of the JRA syndromes.