School start times matter, eveningness does not

Abstract

Morningness-Eveningness (M-E) has been associated with school performance when school activities are arranged early in the morning. This study aims to evaluate this association in 224 adolescents of a secondary school in Montevideo, Uruguay, attending either morning or afternoon shifts. Students' socio-demographic characteristics and performance indicators were similar across shifts, while afternoon-shift students exhibited later circadian preferences. After controlling for socio-demographic and other educational variables, eveningness was associated with lower grades only in morning-shift students. Our study suggests that eveningness influence on school performance is contingent on the temporal arrangement of scholar activities.

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

“…The Uruguayan school system appears as particularly advantageous for chronobiological studies because students are randomly assigned into shifts, creating a natural experiment to compare between similar populations under different social pressures (Estevan et al, 2018). The chronotype distribution of Uruguayan high school students reported in this study (as well as in Uruguayan university students; Silva et al, 2019; Tassino et al, 2016) is extremely delayed, with some of the most extreme late chronotype values reported so far in the literature (Carissimi et al, 2016; Fischer et al, 2017; Masal et al, 2015, 2016; Pande et al, 2018; Porcheret et al, 2018; Randler, 2008; Randler et al, 2009; Roenneberg et al, 2007a; Vollmer et al, 2017).…”

“…In Uruguay, activities are organized usually in up to 4 shifts, lasting between 4 to 6 h, from 0730 to 2330 h. This scheduling maximizes school infrastructure usage and creates a natural experiment for studying the influence of the social clock on adolescent sleep and school performance. In brief, previous studies of adolescents attending different school shifts from Brazil, Mexico, and Uruguay have documented that (1) afternoon-shift students have significantly later chronotypes than morning-shift ones, (2) late chronotypes perform worse at school in the morning shift but not in the afternoon shift, (3) sleep is more advanced and shorter during school days in morning-shift students compared with afternoon-shift ones, (4) weekend sleep duration is similar among students of different shifts, and (5) morning-shift students have shorter average weekly sleep durations than afternoon-shift ones (Arrona-Palacios and Díaz-Morales, 2017; Carissimi et al, 2016; Estevan et al, 2018; Arrona-Palacios et al, 2015; Pereira et al, 2016; Valdez et al, 1996). Although it is generally accepted that cultural and social demands (entertainment, dinner time) influence circadian preferences and sleep (Owens, 2008), to our knowledge, no previous studies have examined social influences on chronotype and sleep duration aside from the school schedule.…”

Afternoon School Start Times Are Associated with a Lack of Both Social Jetlag and Sleep Deprivation in Adolescents

“…Other authors have addressed the difference in sleep patterns between morning and afternoon school shift and have found that, typically, morning-shift students have a shorter sleep duration and increased social jetlag and that these effects are more severe for evening chronotypes (Arrona-Palacios et al., 2015; Arrona-Palacios and Díaz-Morales, 2017; Brandalize et al., 2011; Estevan et al., 2018; Košćec et al., 2014; Lazaratou et al., 2005). One of these studies, performed with adolescents (11-17 years old) in a southern Brazilian city, showed that self-reported sleep duration was longer in afternoon- than in morning-shift students but was also longer than what we report in the current study, suggesting that although overall sleep duration may change between geographic regions, early morning SSTs still have a negative impact on sleep duration (Brandalize et al., 2011).…”

“…These findings are interpreted as the consequence of a better alignment between the schedule of social demands for teenagers and the biological timing of their sleep (reviewed in Lo et al., 2018; Minges and Redeker, 2016; Morgenthaler et al., 2016; Wheaton et al., 2016; Ziporyn et al., 2017). In Latin American countries, it is common for schools to start in tiers, with a morning shift and an afternoon shift (Arrona-Palacios et al., 2015; Arrona-Palacios and Díaz-Morales, 2017; Estevan et al., 2018). In Brazilian middle and high schools, upper- and lower-grade students are respectively assigned to the morning and afternoon shifts (Brandalize et al., 2011).…”

Time to think: Subjective sleep quality, trait anxiety and university start time.

“…In a mixed within-and between-cohort design Chan and colleagues (Chan et al, 2018) reported that a delay in start time of one hour (from 7:30am to 8:30am) was associated with increased total sleep time, higher life satisfaction and reduced depressive symptoms as measured by the Depression and Anxiety Stress Scale (DASS). Taking advantage of the Uruguayan school shift system, whereby pupils are randomly assigned to attend school either early in the morning or afternoon, Estavan and colleagues (Estevan et al, 2018) reported no…”