Who are the individuals with the worst perceived quality of sleep? A population-based survey in southern Brazil

This study aimed to investigate the factors associated with poorer sleep quality. It consisted of a population-based cross-sectional study conducted in Southern Brazil with individuals aged 18 years or older. Participants were selected through a two-stage random sampling strategy and data collection was conducted in 2016. The outcome was self-perceived quality of sleep. Questions regarding the number of hours of sleep and the use of medicines to sleep each week were also asked. Demographic, socioeconomic, behavioral and health conditions were collected through questionnaire. The study sample was composed of 1,300 individuals whose mean age was 46.1 years (SD = 17.3). The prevalence of poor sleep quality was 10.7% (95% CI 9.3% to 12.1%). The poorer the quality of sleep was, the higher the prevalence of the use of medicines to sleep (22.3% versus 10.0% in the overall sample; p < 0.001) and the lower the average amount of daily sleep (6.0 h/day versus 7.3 h/day in the overall sample; p < 0.001). Groups with the worst quality of sleep, in the adjusted analyses, were female (p = 0.012), younger (18 to 39 years versus 60 years or more) (p = 0.048), with poorer perceived diet (p < 0.001), most stressed (p < 0.001), with chronic back pain (p = 0.002), with chronic respiratory disease (p = 0.012), with worse quality of life (p = 0.018) and depression (p = 0.034). Concluding, one out of ten individuals reported poor sleep quality. The results suggest that lifestyle changes could improve the quality of sleep.