We would like to invite you to the Empirical Seminar series organized by the Institute of Economic Research, Slovak Academy of Sciences, Šancová 56 that will be held in hybrid form (online and at the library of the Institute of Economic Research, Slovak Academy of Sciences). The seminar will take place on April 29th, 2026 at 11.00 (CET).
The speaker will be Jakub Lonsky (School of Economics, University of Edinburgh, Scotland).
The topic of the seminar is: Breaking the Early Bell: Lessons from the First Statewide Mandate on School Start Times
Authors: Jakub Lonsky
Abstract:
This study investigates the effects of California’s Senate Bill 328 (SB 328)—the first state legislation requiring later school start times for middle and high schools—on adolescent sleep, mental health, and academic outcomes. Drawing on data from the Youth Risk Behavior Surveillance System (YRBS) for high school students (grades 9–12) and the American Time Use Survey (ATUS), which includes sleep duration for adolescents aged 15 above and bedtimes and wake-up times for children under 13, we analyze shifts in sleep patterns and mental health metrics. We then examine the impact on academic performance using district-level data from the Stanford Education Data Archive (SEDA) for students in grades 3–8 and SAT scores for high school students. Employing difference-in-differences (DID) and matched DID methods, we find that SB 328 led to a 14% increase in the share of students sleeping at least 8 hours per night, consistent with CDC recommendations for adolescents. We find suggestive evidence of a reduction in certain mental health problems, particularly difficulties concentrating, though the results are imprecisely estimated and not robust across specifications. Finally, we find evidence of significant improvements in math and English scores in grades 3–8 (approximately a .1 standard deviation increase), while SAT scores rose by 2%. We uncover substantial heterogeneity in the policy’s effects, with larger improvements in sleep and mental health among boys and Hispanic students, and larger academic gains among Hispanic students.
The seminar will be co-chaired by Filip Ostrihoň.
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