Depressive symptoms and sleep: a population-based polysomnographic study.

The goals of the present study were to determine the prevalence of depression in the adult population of Sao Paulo, Brazil and to explore the relationship among sociodemographic, physical and psychological factors, sleep-related symptoms and polysomnography parameters. Participants of a cross-sectional study (N = 1101) were administered questionnaires and submitted to polysomnography. A score > 20 in the Beck Depression Inventory was used to describe depression. Results revealed that the prevalence of depression was 10.9%. Estimates were higher in women and were significantly higher among housewives, non-workers and individuals with lower education and income. A combination of sleep-related symptoms and impaired quality of life was 2.5 times more frequent among depressed than non-depressed. Co-morbid insomnia and anxiety were positively associated to depressive symptomatology. There were no alterations in the polysomnography parameters, in either group. The occurrence of sleep apnea with values on the apnea-hypopnea index ≥ 5 was similar and frequent in both groups (around 30%). The findings suggest that depressive symptoms were associated with low education, low income, severe comorbid symptomatology, and impaired quality of life. Considering the high prevalence of sleep apnea, these results point to potential social and financial burdens associated with the depressive symptomatology and various sleep diagnoses.