School start time delays and high school educational outcomes: Evidence from the START/LEARN study

Sarah A. James, Darin J Erickson, Sara Lammert, Rachel Widome

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Introduction: Delaying high school start times extends adolescents' nightly sleep, but it is less clear how it affects educational outcomes. We expect links between school start time delays and academic performance because getting enough sleep is a key input to the cognitive, health, and behavioral factors necessary for educational success. Thus, we evaluated how educational outcomes changed in the 2 years following a school start time delay. Methods: We analyzed 2153 adolescents (51% male, 49% female; mean age 15 at baseline) from START/LEARN, a cohort study of high school students in the Minneapolis—St. Paul, MN, USA metropolitan area. Adolescents experienced either a school start time delay (“policy change schools”) or consistently early school start times (“comparison schools”). We compared patterns of late arrivals, absences, behavior referrals, and grade point average (GPA) 1 year before (baseline, 2015–2016) and 2 years after (follow-up 1, 2016–2017 and follow-up 2, 2017–2018) the policy change using a difference-in-differences analysis. Results: A school start time delay of 50–65 min led to three fewer late arrivals, one fewer absence, a 14% lower probability of behavior referral, and 0.07–0.17 higher GPA in policy change schools versus comparison schools. Effects were larger in the 2nd year of follow-up than in the 1st year of follow-up, and differences in absences and GPA emerged in the second year of follow-up only. Conclusions: Delaying high school start times is a promising policy intervention not only for improving sleep and health but for improving adolescents' performance in school.

Original languageEnglish (US)
Pages (from-to)751-763
Number of pages13
JournalJournal of Adolescence
Issue number4
StatePublished - Jun 2023

Bibliographical note

Funding Information:
The authors thank the adolescents who participating in the START study, the districts that welcomed us to do research in their schools, the START data collectors, Bill Baker for his work to manage the data, and Kate Bauer for sharing great ideas. This study is supported by funding from the National Institutes of Health's (NIH) Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) through awards R01 HD088176, P2C HD041023, and T32 HD095134.

Publisher Copyright:
© 2023 The Authors. Journal of Adolescence published by Wiley Periodicals LLC on behalf of Foundation for Professionals in Services to Adolescents.


  • attendance
  • behavior
  • grade point average
  • late arrivals
  • school start time
  • sleep

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural


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