Objective: Sleep disorders in patients diagnosed with ankylosing spondylitis are frequently associated with back pain, depression, chronic disease, and anxiety. This study analyzed the correlations between sleep quality, disease activity, and functional scores. Methods: This study used the Pittsburgh sleep quality index (PSQI) with 143 patients and 143 healthy volunteers who visited the Rheumatology Clinic of the Faculty of Medicine at Ankara University. The Bath ankylosing spondylitis disease activity index (BASDAI) scores, Bath ankylosing spondylitis functional index (BASFI) functional scores, and C-reactive protein biochemical parameters were extracted from the patients’ records. Results: There were no significant differences between the groups in terms of age or sex. However, the control group showed significantly better outcomes in subjective sleep quality, sleep latency, sleep disturbances, daytime functioning, and total PSQI scores. In the patient group, a significant positive correlation was observed between PSQI scores and BASDAI, BASFI demonstrating that poorer sleep quality was associated with increased disease activity, reduced functional status, and elevated inflammation. Conclusion: The data indicated a direct correlation between sleep disorders, disease activity, and other parameters. Notably, sleep disorders are less prevalent among patients receiving treatment with anti-tumor necrosis factor antibodies.