The Power of Flexible School Start Times:: Longitudinal Associations with Sleep, Health, and Academic Performance.

Abstract

PURPOSE Early school start times (SSTs) are linked to adolescents' sleep deficits, but delaying schedules is often difficult. Flexible school start models may offer a viable alternative, though remain understudied. METHODS This longitudinal study examined the impact of a flexible model on sleep, health, and academic performance in two secondary schools in Switzerland. All students were invited to complete surveys before (spring 2022) and after (spring 2023) implementation of a flexible SST model. Main outcomes included sleep-related and health-related variables and academic performance. RESULTS In total, 351 students completed the baseline survey and 403 the follow-up; 212 participated at both time points. The median age was 14 years and about two-thirds indicated male sex. Under the flexible model, 95% of students used the later-start option. The median SST was delayed by 38 minutes (n = 711, β = .57, 95% confidence interval [.53, .62], p < .001, R2β = .52), with corresponding significant delays in wake times and increased sleep duration on school days. Among the paired subsample, SST delay was significantly associated with increased school day sleep duration (n = 205, β = .51 [.05, .94], p = .03, R2β = .02). No worsening was observed. Improvements included reduced problems falling asleep, fewer students with clinically low health-related quality of life, and higher scores in mathematics and English. DISCUSSION When offered the choice to start school later, students took it, resulting in measurable improvements in sleep, health, and academic outcomes. Therefore, flexible school schedules may offer an effective way to address adolescent sleep deficits.