Sleep disturbances are common among adult populations and can have a significant effect on daytime activities. The aim of this study is to determine the prevalence of sleep problems and subjective sleep quality in the adult population of Tehran, Iran.From an urban community of Tehran, a random sample of 3400 adult men and women were selected by a cross-sectional design. Using the Persian version of the Pittsburgh Sleep Quality Index (PSQI), subjects were interviewed face-to-face. There were 3114 completed questionnaires returned and analyzed.The mean age of the subjects was 43.57 (± SD 17.5) years. Overall 37% (95% CI: 35-39) of the population were categorized as poor sleepers. The PSQI > 5 showed 27% were males versus 35% among females. The global PSQI scores ranged from 4.20 ± 2.67 to 5.60 ± 3.74 for males and 5.03 ± 3.00 to 7.97 ± 4.31 for females by age groups. The difference across age groups for global PSQI score was significant in females (P < 0.01).The prevalence rate of sleep complaints in this population-based study was high. Females, older adults, widows and separated couple were the most important risk factors for sleep disturbances.