Association of Delaying School Start Time With Sleep–Wake Behaviors Among Adolescents

Kaitlyn M. Berry, Darin J. Erickson, Aaron T. Berger, Kyla Wahlstrom, Conrad Iber, Kelsie M. Full, Susan Redline, Rachel Widome

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Purpose: Few adolescents spend enough time asleep on school nights. This problem could be addressed by delaying high school start times, but does this translate to reduced prevalence of sleep–wake problems like awakening too early or feeling sleepy during the day? Methods: The START study (n = 2,414) followed a cohort of students from five Minnesota high schools to evaluate impacts of school start time delays. Participants were enrolled in ninth grade (Baseline) when all schools started early (7:30 or 7:45 A.M.). At Follow-Up 1 (10th grade) and Follow-Up 2 (11th grade), two schools had delayed their start times by 50 and 65 minutes while three comparison schools started at 7:30 A.M. Six sleep–wake behaviors were assessed at all three time points via survey. Generalized estimating equation models were used to investigate changes in sleep–wake problems between policy change and comparison schools. Results: The prevalence of sleep–wake problems at Baseline ranged from 11% for being late to class due to oversleeping to 48% for needing to be told to wake multiple times in the morning. Compared to students from comparison schools, students at policy change schools reported smaller increases in the prevalence of feeling sleepy daily and oversleeping and being late to class between 9th and 11th grade. After implementation of the delayed start, awakening too early was more common among students at policy change schools compared to the comparison schools. Conclusions: This longitudinal study provides evidence that delaying high school start times reduces daytime sleepiness and school tardiness.

Original languageEnglish (US)
Pages (from-to)831-837
Number of pages7
JournalJournal of Adolescent Health
Issue number5
Early online dateJun 5 2021
StatePublished - Nov 2021

Bibliographical note

Funding Information:
The authors would like to thank the adolescents participating in the START study, the districts that welcomed us to do research in their schools, the START data collectors, and Bill Baker for his work to manage the data. Thank you to Kate Bauer for sharing your great ideas. The START study was supported by grant R01 HD088176 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) of the NIH. Ms. Berry's time was supported by a NICHD training grant (T32 HD095134); Dr. Full's time was supported by a National Health Lung and Blood Institute (NHLBI) training grant (T32 HL007779). The authors also gratefully acknowledge support from the Minnesota Population Center (grant P2C HD041023), which is funded by NICHD. Funders did not play any role in the study design; the collection, analysis, and interpretation of the data; the writing of the manuscript; or the decision to submit the manuscript for publication.

Publisher Copyright:
© 2021 Society for Adolescent Health and Medicine


  • Adolescents
  • High school
  • School start times
  • Sleep
  • Sleep–wake problems

PubMed: MeSH publication types

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


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