Abstract
The papers by Carvalho-Mendes and Estevan in this issue bring to the attention of the circadian and sleep fields again issues of adolescence and school start times. A recent SRBR Public Outreach Brief (Dunster et al., 2019) on school start times highlights the concern of our scientific community about potential challenges to teen sleep, behavior, mood, well-being, and academic performance when school schedules are out of sync with students’ biological rhythms.
A substantial delay in chronotype across the second decade of human life was shown exquisitely by Till Roenneberg in his now classic paper (2004). Reports from the 1990’s of studies in Latin America (Andrade et al., 1992) and North America (Carskadon et al., 1993) showed an association of pubertal stage and morningness-eveningness in the 1990’s. Much earlier, around the turn of the 20th century, Terman and Hocking (1913) attributed insufficient sleep of adolescents to a shift from a matinal to a vesperal sleep propensity. Thus, this adolescent pattern is not breaking news.
I note that Mark Mahowald (1937-2020) was one of the earliest to identify the unhealthy nature of early school bells for high school students after attending my 1993 lecture at the Minnesota Regional Sleep Disorders association: “Sleepiness in Adolescents: A Crisis Situation, A National Problem.” Indeed, Mahowald successfully lobbied the Minnesota state neurology association and subsequently the Minnesota branch of the American Medical Association to recommend later opening bells for high schools due to the harm that befell teen sleep with early rising. Mahowald connected the dots from delayed sleep to sleepiness to early school bells. Circadian scientists and pediatric sleep researchers around the globe were not long to follow the trail: Israel, Australia, Europe, Latin America, Southeast Asia, China, and more recently African scientists have engaged in the study of adolescent school start time schedules.
The special role of the papers in this issue of JBR is not only that they emanated from Latin American countries, but that they also include careful measures of chronotype, sleep duration, quality, and timing in adolescents attending school in systems with tiered instructional schedules. Another strength of both studies is that they were performed in naturalistic circumstances, where students were randomly assigned to shifts by the schools. Further, the students experienced different schedules concurrently. Both studies provide evidence for longer sleep duration and reduced social jet lag in those teens with later school days and an association of these outcomes to chronotype. These results in part mirror those of Koscec Bjelajac and colleagues (2020), whose work was performed in Zagreb, Croatia, where students’ school schedules rotated weekly between early and late. Again, later school days paralleled greater sleep.
These associations—school start time and sleep in adolescents–are well established and accepted by the scientific community. Medical and public health organizations and a number of school officials have also acknowledged the challenge of early school bells for adolescents. Less well examined are family and cultural factors associated with this interaction. Estevan and colleagues note the relevance of the Uruguayan culture of late-evening family dinner time to the findings. This study and its evaluation of cultural contributions is an important step.
Failure to acknowledge the current social/political atmosphere sweeping the globe with concern for systemic racial minority disparities would be an egregious oversight. As scientists concerned with circadian and sleep health in all humans, we cannot ignore and must explore and ultimately help to eliminate the exacerbation of educational disparities consequent to the adolescent sleep/school issue associated with racially and economically oppressed communities. Circadian and sleep researchers must start to lean in to measure the factors, with a goal to advise and develop strategies to implement changes for those teens at greatest risk due to social, cultural, racial, and economic disparities. If a child or teen needs to arrive at the school even earlier than the privileged students to access meals, that child is disadvantaged. If a teen oversleeps and misses the bus but has no parent who can drive them to school, that teen is disadvantaged. In the United States, Black youngsters are most likely to experience such economic disadvantages, and the schools in their communities are least likely to consider health issues of school start times. If we expand our science, we can help inform new policies that are equitable for all and reduce the unequal harm of requirements that are mistimed for students. [#BLM]
In the current era of Covid-19 lockdowns and school closures, school and sleep may be easier for certain adolescents to navigate, though more challenging for others. With asynchronous and remote learning, students not only no longer may confront early school bells, but they are also missing important temporal signals to regulate timing of their activities. Individual differences in teens’ responses to these factors are as yet unknown. The future of education is unclear for many communities, and no options seem to be off the table. Indeed, a looming assortment of teaching and learning plans offers the opportunity for research that expands the questions that can be asked and the approaches that can be implemented to address strategies for students’ adjustments. I challenge such science to assess the role of race, ethnicity, and economic status.