Objective: It is known that anxiety and depression are associated with sleep disorders and many systemic diseases. This study aims to analyse the relationship between anxiety, depression symptoms and sleep parameters among the patients subjected to polysomnographic recording. Material and Methods: A total of 808 patients who were subjected to a polysomnographic recording were included in the retrospective cross-sectional and hospital-based study. Body mass index (BMI) was calculated. Anxiety and depression symptoms were evaluated using the Beck anxiety and Beck depression inventory. Patients were divided into groups according to anxiety and depression scores. The apnoea hypopnea index (AHI), oxygen desaturation index (ODI), and peripheral oxygen saturation (SaO2) were obtained from the polysomnographic recordings. Results: In the study, there were 528 (65.3%) male and 280 (34.7%) female patients with the mean age of 47.64 ± 12.25 (18-82). Depression was detected in 307 (38.0%) patients according to Beck depression score. Mild anxiety symptoms were detected in 516 (63.9%), moderate anxiety symptoms in 215 (26.6%) patients and severe anxiety symptoms in 77 (9.5%) patients according to Beck anxiety score. There was a statistical difference for all polysomnographic parameters in depression and anxiety severity groups (p=0.001). In patients with depression had lower free-T3 and higher C-reactive protein (CRP) levels (p=0.001, p=0.014). The difference between thyroid stimulating hormone (TSH) and FT4 levels was determined according to the severity of the depression (p=0.037, p=0.047). CRP was higher in patients with severe anxiety (p=0.008); and free-T3 was lower in patients with moderate and severe anxiety (p=0.003, p=0.001). In the logistic regression analysis, free-T3, minimum SaO2 and BMI had an impact on anxiety (p=0.002, p=0.033, p=0.031) and depression (p=0.001, p=0.017, p=0.035). Conclusion: Anxiety and depression symptoms are affected by numerous factors, especially sleep characteristics. Minimum SaO2, CRP and free-T3 are main predisposing factors on anxiety and depression.