Chronotype at the beginning of secondary school and school timing are both associated with chronotype development during adolescence

Abstract

The misalignment between late chronotypes and early school start times affect health, performance and psychological well-being of adolescents. Here we test whether, and how, the baseline chronotype (i.e. chronotype at the beginning of secondary school) and the school timing affect the magnitude and the direction of the developmental change in chronotype during adolescence. We evaluated a sample of Argentinian students (n = 259) who were randomly assigned to attend school in the morning (07:45 a.m.–12:05 p.m.), afternoon (12:40 p.m.–05:00 p.m.) or evening (05:20 p.m.–09:40 p.m.) school timings. Importantly, chronotype and sleep habits were assessed longitudinally in the same group of students along secondary school (at 13–14 y.o. and 17–18 y.o.). Our results show that: (1) although chronotypes partially align with class time, this effect is insufficient to fully account for the differences observed in sleep-related variables between school timings; (2) both school timing and baseline chronotype are independently associated with the direction and the magnitude of change in chronotype, with greater delays related to earlier baseline chronotypes and later school timings. The practical implications of these results are challenging and should be considered in the design of future educational timing policies to improve adolescents’ well-being.

A better alignment between chronotype and school timing is associated with lower grade retention in adolescents

“…This could be due to the fact that during 1 st year students' internal timing is better aligned with afternoon school timing, while during 5 th year, it is better aligned with the evening school timing. This is especially plausible considering that students in first year present earlier chronotypes 56 .…”

“…Together, these results suggest that during their 1 st year of school, students are better aligned to the afternoon school timing than to the evening school timing, but this difference disappears or even reverses during their last year. This might be because chronotypes become later during adolescence 7,8,55,56 but school start times do not change. As a result, the misalignment between students' internal timing and earlier school schedules increase with age.…”

“…Thus, if the school timing delay policy should be applied only to some students, older students probably will obtain higher benefits. Also, based on the results presented hereanother 20 policy could be assessing students' chronotype before starting their first year of secondary school and assign those with later chronotypes to later school timings,evenconsidering that the change in chronotype throughout secondary school also depends on baseline chronotype 56 . Another practical implication of our results is the possibility of reorganizing the order of school subjects, letting math for the last hours of the school day, particularly during morning school timing.…”

“…Here, we present a longitudinal study, further capitalizing this unique educational setup. We evaluated students in their 1 st (13-14 years old) and 5 th (17-18 years old) year of secondary school 55,56 . This longitudinal design allows us to assume that the differences observed between 1 st and 5 th year in students' grades are not due to interindividual variability but due to age-related changes.…”

“…First, we test whether academic performance differs between school timings in 1 st and 5 th year: a better performance in one of the three school timings could indicate a better alignment between school schedules and students' internal timing. As Argentinian adolescents' present particularly late chronotypes 56 , we hypothesize that students attending afternoon and/or evening school timings will present better academic performance than those attending school in the morning (synchrony effect). Second, we study how synchrony and chronotype effects can modulate academic performance considering interindividual differences in adolescents' chronotype.…”