Chronotype, Light Exposure, Sleep, and Daytime Functioning in High School Students Attending Morning or Afternoon School Shifts

Abstract

Adolescent maturation is associated with delays of the endogenous circadian phase. Consequently, early school schedules may lead to a mismatch between internal and external time, which can be detrimental to adolescent sleep and health. In parallel, chronotype is known to play a role in adolescent health; evening chronotype adolescents are at higher risk for sleep problems and lower academic achievement. In the summer of 2008, Kénogami High School (Saguenay, Canada) was destroyed by fire. Kénogami students were subsequently relocated to Arvida High School (situated 5.3 km away) for the 2008-2009 academic year. A dual school schedule was implemented, with Arvida students attending a morning schedule (0740-1305 h) and Kénogami students an afternoon schedule (1325-1845 h). This study aimed to investigate the effects of such school schedules and chronotype on sleep, light exposure, and daytime functioning. Twenty-four morning and 33 afternoon schedule students wore an actigraph during 7 days to measure sleep and light exposure. Academic achievement was obtained from school. Subjects completed validated questionnaires on daytime sleepiness, psychological distress, social rhythms, school satisfaction, alcohol, and chronotype. Overall, afternoon schedule students had longer sleep duration, lower sleepiness, and lower light exposure than morning schedule students. Evening chronotypes (E-types) reported higher levels of sleepiness than morning chronotypes (M-types) in both morning and afternoon schedules. Furthermore, M-types attending the morning schedule reported higher sleepiness than M-types attending the afternoon schedule. No difference was found between morning and afternoon schedule students with regard to academic achievement, psychological distress, social rhythms, school satisfaction, and alcohol consumption. However, in both schedules, M-type had more regular social rhythms and lower alcohol consumption. In summary, this study emphasizes that an early school schedule is associated with detrimental effects in terms of sleep deprivation and daytime sleepiness, even for M-types. Furthermore, irrespective of school schedule, E-type adolescents face an increased risk for poor daytime functioning.

Morningness–eveningness is not associated with academic performance in the afternoon school shift: Preliminary findings

“…However, to our knowledge, only one study by Martin et al . () reported mean MESC scores according to their school shift. Mexican adolescents from the morning shift were more morning oriented, and adolescents from the afternoon shift were more evening oriented ( M = 28.27, SD = 4.58; M = 24.06, SD = 5.09, respectively) compared to Canadians from the morning shift and from the afternoon shift ( M = 27.6, SD = 1.0; M = 26.9, SD = 0.9, respectively).…”

“…As a result, the students were relocated to another school, and because of the limited number of classrooms available, morning and afternoon school schedules were implemented. This provided a novel opportunity to analyse these dual school shifts, which were nonexistent in Canada (Martin, Gaudreault, Perron, & Laberge, ). The study reported that afternoon students had longer sleep duration, less sleepiness, and lower light exposure than morning students – reporting the same results as the aforementioned studies.…”

Time to learn: How chronotype impacts education

“…In general, sleep duration was significantly longer for students attending the afternoon shifts. This was observed even in morning types who also reported higher sleepiness during the morning shift (Martin et al, ). Although the sample of students was small ( N = 57), the authors found no significant difference in grades between students attending the morning and the afternoon shift, and overall evening types did not obtain lower grades compared to morning types.…”

“…Two other studies have assessed differences in sleep between high school students attending morning or afternoon lectures, taking chronotype into account (Koscec, Radosevic-Vidacek, & Bakotic, 2013;Martin, Gaudreault, Perron, & Laberge, 2016). In general, sleep duration was significantly longer for students attending the afternoon shifts.…”

Accuracy of the GENEActiv Device for Measuring Light Exposure in Sleep and Circadian Research

“…In field-based sleep and circadian studies, light exposure is currently widely measured using wrist-worn devices (e.g., [6][7][8][9][10]), due to their convenience and availability. GENEActiv devices are an affordable tool commonly used for this purpose, with 37 studies since 2014 having used the device's light outputs (Google Scholar search terms "GENEActiv"+"light"+"lux" or "GENEActiv"+"light"+"lx").…”