Sleep duration trajectories from adolescence to emerging adulthood: Findings from a population-based birth cohort.

This study aimed to describe longitudinal trajectories of sleep duration, among adolescents and adults from the Pelotas (Brazil) 1993 Birth Cohort, as well as characterize different trajectories groups according to socioeconomic, demographic and behavior characteristics. Sleep duration, hours per day (from Monday to Friday), bedtime and wake-up time were self-reported by participants at ages 11, 18 and 22 years. Covariables included socioeconomic, demographic, health and behavior characteristics. Trajectory analysis was performed using a semi-parametric, group-based modelling approach. Prevalence and 95% confidence interval were obtained to describe covariables and sleep trajectory groups. Chi-square test was employed in statistical analysis and all analyses were stratified by sex. A total of 3.395 individuals were included in the analysis. In both sexes, bedtime became later across years, while wake-up time presented little variation. Differences according sex were more pronounced from 18 years onwards. Three trajectories of sleep duration from 11 to 22 years were identified for males: "increase and maintenance" (3.4%), "fast reduction and maintenance" (45.0%) and "constant reduction" (51.6%). While in females the trajectories identified were: "increase and decrease" (2.4%), "fast reduction and maintenance" (25.6%) and "constant reduction" (72.0%). Men and women who belong to trajectories with longer sleep durations were more likely to present higher percentages of some risk behaviors and poor socioeconomic condition. Our results have provided longitudinal information regarding sleep duration trajectories in a medium-sized city in Brazil, aiming at filling an existing gap in literature from low- and middle-income countries.