Background: 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. Methods: 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. Results: 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). Conclusion: 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.