Effects of a 20 minutes delay in school start time on bed and wake up times, daytime tiredness, behavioral persistence, and positive attitude towards life in adolescents

Objectives Preliminary evidence suggests that delaying school start times is an effective tool for improving adolescent sleep duration. Our study assessed whether a policy driven 20-minute delay in school start times led to an increase in adolescents' weekday bed and wake up times. Method Data collected via school satisfaction surveys concerned 663 students (45.2% females, Mean age: 14.91 years, SD = 0.58 years) in three lower-track secondary schools in Switzerland. Of all the students, 249 experienced a policy-driven 20-minutes school start time change (SSTc), from 7.40 am to 8.00 am between the eighth and ninth grade, while 414 students did not (Comparison Group/CG). Students filled out the survey twice, at the end of their eighth and ninth grades, respectively, and reported their weekday bed and wake up times, daytime tiredness, behavioural persistence, and positive attitude towards life. Results Generalized estimating equations models of bed and wake up times showed that there was a significant delay in both the bed and wake up times of the students in the SSTc group. Multilevel analyses revealed that students in the SSTc group did not significantly differ from CG students in daytime tiredness, behavioural persistence, and positive attitude towards life. Conclusions Findings suggest that not only wake up times but also bed times may shift later when school start times are delayed. The 20 minutes delay in school start times may have been too slight to have an impact on daytime tiredness, behavioral persistence and positive attitude towards life.