Later school start times in a flexible system improve teenage sleep

Abstract

Sleep deprivation in teenage students is pervasive and a public health concern, but evidence is accumulating that delaying school start times may be an effective countermeasure. Most studies so far assessed static changes in schools start time, using cross-sectional comparisons and one-off sleep measures. When a high school in Germany introduced flexible start times for their senior students—allowing them to choose daily between an 8 am or 9 am start (≥08:50)—we monitored students’ sleep longitudinally using subjective and objective measures. Students (10–12th grade, 14–19 y) were followed 3 weeks prior and 6 weeks into the flexible system via daily sleep diaries (n = 65) and a subcohort via continuous wrist-actimetry (n = 37). Satisfaction and perceived cognitive outcomes were surveyed at study end. Comparisons between 8 am and ≥9 am-starts within the flexible system demonstrated that students slept 1.1 h longer when starting school later—independent of gender, grade, chronotype, and frequency of later starts; sleep offsets were delayed but, importantly, onsets remained unchanged. Sleep quality was increased and alarm-driven waking reduced. However, overall sleep duration in the flexible system was not extended compared to baseline—likely because students did not start later frequently enough. Nonetheless, students were highly satisfied with the flexible system and reported cognitive and sleep improvements. Therefore, flexible systems may present a viable alternative for implementing later school starts to improve teenage sleep if students can be encouraged to use the late-option frequently enough. Flexibility may increase acceptance of school start changes and speculatively even prevent delays in sleep onsets through occasional early starts.

Short Sleep Duration and Extremely Delayed Chronotypes in Uruguayan Youth: The Role of School Start Times and Social Constraints

“…Social jetlag (SJL), a behavioral index of circadian misalignment (Wittmann et al, 2006), has been related to adolescent school performance (Díaz-Morales and Escribano Barreno, 2015; Haraszti et al, 2014) and cognition (Panev et al, 2017). Based on this evidence, there have been several attempts of delaying school start times and making them more flexible, some of which have resulted in reported improvements in sleep (increased sleep duration and reduced sleepiness), school attendance, performance, mood, and negative behaviors (American Academy of Pediatrics, Committee on Adolescence, and Council on School Health, 2014; American Medical Association, 2016; Bowers and Moyer, 2017; Dunster et al, 2018; Fischer et al, 2008; Kelley et al, 2015; Louzada and Pereira, 2019; Minges and Redeker, 2016; Watson et al, 2017; Wheaton et al, 2016; Winnebeck et al, 2019).…”

One year later: longitudinal effects of flexible school start times on teenage sleep and subjective psychological outcomes

“…Notably, our participants accumulated fewer late starts per week than expected. We had observed this for cohort 1 [48] but now saw this confirmed in cohort 2, where participants (n=105) chose to skip the first period only on a median of 24% of their schooldays (IQR: 10-47), which equates to 1.…”

“…We had previously investigated sleep changes and psychological benefits following a switch to a flexible start system -a highly overlooked start system that might offer some interesting advantages [48]. Here, we now report on the longer-term effects of this flexible system after 1 year of exposure.…”

“…Differences in baseline characteristics between the 33 and 16 students were tested and not statistically significant (chronotype, social jetlag, gender, grade level; all p>0.05), except for age (t(47)=-2.933, p=0.005, d=0.893) with the missing students on average 0.8 years older. Minimal filter criteria were: i) sleep information for ≥5 schooldays and ≥3 weekend days at each time point and ii) congruent, plausible data (more detailed information in [48]). For 8AM or ≥9AM-start comparisons, we additionally filtered for at least 2 8AM-days and at least 2 ≥9AM-days per person.…”

Validation of the Munich Actimetry Sleep Detection Algorithm for estimating sleep-wake patterns from activity recordings

“…For the validation against sleep logs, we used two samples from previous studies, an adolescent sample and one young adult sample. The adolescent sample was collected over 9 weeks in 45 German high school students (mainly Caucasians), of which 34 participants (22 females, M = 16.7 y, SD = 1.2, range = 14-19) provided high-quality data in both their sleep logs and actimetry records (median of 54 days) and were used for further analyses (Winnebeck et al, 2020). The young adult sample was collected over 4-6 weeks in 30 German participants (mainly Caucasians), of which 28 (13 females, M = 22.8 y, SD = 3.6, range = 19-33) provided complete data across both methods (median of 34 days) and made up the final adult sample (Ghotbi et al, 2020).…”