Obstructive sleep apnea (OSA) is a common sleep disorder which can result in mood problems. The aim of this study was to evaluate the severity of depression and anxiety symptoms as the most prevalent psychological disturbances present in different severity of OSA. We performed a cross-sectional study of 685 recently diagnosed sleep-disordered patients, over the age of 18, referred to Noor Sleep Lab from August 2008 to November 2010. The participants filled the Beck depression inventory-II (BDI-II) and the Beck anxiety inventory (BAI) to assess the depression and anxiety symptoms. We collected other characteristics of subjects such as age, sex, body mass index (BMI) and Epworth sleepiness scale (ESS). Apnea hypopnea index (AHI) was determined by an overnight polysomnography. Mean age of the participants was 47.63 years (SD 11.73). More than half of patient had some degrees of depression and anxiety. AHI showed no significant correlation with BDI (p = 0.105, r = -0.070) or BAI (p = 0.712, r = -0.016). Obesity was not either correlated with depression or anxiety (p = 0.18, r = 0.05). Nonetheless, ESS was weakly correlated with depression (p = 0.001, r = 0.148) and anxiety scores (p = 0.006, r = 0.120). BMI and ESS means were significantly higher in patients with severe OSA (p = 0.000). In comparison with men, the severity of depressive and anxiety symptoms was significantly higher in women (p = 0.000). In this cross-sectional study of patients with sleep problems, OSA was not associated with severity of depression and anxiety symptoms.