Differences in time use among chronotypes in adolescents

There are only few studies investigating the lifestyle habits of adolescents and their relationship to morningness-eveningness, but some indicate that morningness may be a protective factor. Here, we used a method of time-budget sampling to assess the difference between chronotypes in time budgets in adolescents while controlling for age and gender. We used the Composite Scale of Morningness to assess chronotype and a timetable approach to assess leisure activities. There was a significant influence of gender and chronotype on the time budgets. In particular, morning types spent less time watching television, less time at the computer, but more time reading and in physical activity. These variables generally may be associated with a healthier lifestyle, because, for example, screen time (computer and television) is considered as a risk factor for obesity. Concerning socializing with friends, evening types spent more time with their friends than intermediate types and morning types. On weekdays, sleep duration was shortest in evening types. Girls spent less time with sports/physical activities, television viewing and at the computer while they reported more time reading. There were no differences between boys and girls regarding time spent with peers. Sleep duration did not differ on weekdays but on the weekends with girls sleeping longer.