BACKGROUND: Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders with chronic abdominal pain and altered bowel habit without any organic reason. Sleep disorders may be associated to IBS. OBJECTIVE: We aimed to assess sleep disturbances and depression-anxiety-stress in IBS patients. METHODS: In this analytical cross sectional study from November 2013 to May 2014, A total of 123 IBS patients were recruited by simple random sampling. IBS was diagnosed using ROME-III criteria. Demographic and basic data were driven from all patients then Pittsburg Sleep Quality Index questionnaire was utilized to estimate sleep quality and DASS (depression anxiety stress scale) questionnaire was filled out for depression, anxiety and stress. RESULTS: The mean age of patients was 29±9, where 48 cases (39%) were male. Twelve cases (10%) had a background disease. Types of IBS in patients were included 38% diarrhea, 42% constipation and 20% mixed. From all IBS patients 87 (71%) cases had depression, 97 (79%) patients stress, 94 (76%) patients had anxiety. Seventy-six (62%) cases of IBS patients had poor sleep quality. Simultaneously employing predictors demonstrate that gender, background disease, and type of IBS did not statistically significant. On the other hand, depression (P=0.034, OR=2.35), anxiety (P=0.011, OR=3.022), and stress (P=0.029, OR=2.77) were significantly effect on sleep quality in poor sleepers. CONCLUSION: Many of IBS patients is suffering from poor sleep quality. It seems that sleep disorder should be considered and treated in this patients.