Correlates of self-reported weekday sleep duration in adolescents: the 18-year follow-up of the 1993 Pelotas (Brazil) Birth Cohort Study

Objective: To investigate factors associated with sleep duration in adolescence. Methods: Data are from the 1993 Pelotas Birth Cohort Study of 5249 live births. Of these individuals, 4563 were located for follow-up at 18 years of age, and 4106 agreed to be interviewed (follow-up rate 81.3%). Sleep duration was continuously assessed by survey as hours per weekday. Additional covariates were collected during the perinatal period and at the 11- and 18-year follow-ups. Linear regression models were used to estimate associations between sleep duration and its hypothesized influences. All analyses were sex-stratified. Results: The average sleep duration among participants was 8.4 hours (standard deviation 1.9). Longer sleep duration at 18 years of age was associated with the following perinatal factors: low maternal schooling, low family income, maternal black skin color, and low birth weight; and with the following factors measured at 18 years of age: being out of school, low achieved schooling, low family income, absence of depressive symptoms, and high screen time. Conclusion: Social and demographic variables may play an important role in determining adolescents' sleep duration, but the nature of these relationships in Brazil may differ from those observed in higher income contexts. (C) 2016 The Authors. Published by Elsevier B.V.