Sleep-wake cycle expression in adolescence: Influences of social context

Sleep/wake cycle (SWC) characteristics change with development. During adolescence there is a reduction in night sleep duration. A difference between sleep duration on weekdays and at weekends is also observed. Adolescents usually sleep much longer at weekends. A SWC phase delay related to puberal stage is described. In this study, we have investigated SWC patterns among populations living in different environments, either urban (one population) or non-urban (two populations). 423 adolescents studying in the morning period participated in the study. Some characteristics of adolescents' SWC have been investigated based on a questionnaire previously validated by an actigraphic study. Bedtimes and wake up times were compared by means of ANOVA. Adolescents living in the urban environment showed later bedtimes (p < 0.001) and wake up times (p < 0.001) when compared with adolescents living in rural environments. No differences were found when the rural populations were compared.