Delayed high school start times later than 8:30am and impact on graduation rates and attendance rates

Sleep Health. 2017 Apr;3(2):119-125. doi: 10.1016/j.sleh.2017.01.002. Epub 2017 Feb 1.


Objectives: The first purpose of this study was to investigate changes in high school graduation rates with a delayed school start time of later than 8:30am. The second aim of the study was to analyze the association between a delayed high school start time later than 8:30am and attendance rates.

Design: In the current study, a pre-post design using a repeated-measures analysis of variance was used to examine changes in attendance and graduation rates 2 years after a delayed start was implemented.

Setting: Public high schools from 8 school districts (n=29 high schools) located throughout 7 different states. Schools were identified using previous research from the Children's National Medical Center's Division of Sleep Medicine Research Team.

Participants and measurements: A total membership of more than 30,000 high school students enrolled in the 29 schools identified by the Children's National Medical Center's Research Team. A pre-post design was used for a within-subject design, controlling for any school-to-school difference in the calculation of the response variable. This is the recommended technique for a study that may include data with potential measurement error.

Results: Findings from this study linked a start time of later than 8:30am to improved attendance rates and graduation rates.

Conclusions: Attendance rates and graduation rates significantly improved in schools with delayed start times of 8:30am or later. School officials need to take special notice that this investigation also raises questions about whether later start times are a mechanism for closing the achievement gap due to improved graduation rates.

Keywords: Adolescent sleep; Attendance rates; Delayed school start times; Graduation completion; Graduation rates; High school bell times; Inadequate sleep; Insufficient sleep; Student social–emotional health.

MeSH terms

  • Absenteeism*
  • Adolescent
  • Educational Status*
  • Female
  • Humans
  • Male
  • Schools / statistics & numerical data*
  • Sleep / physiology*
  • Students / psychology*
  • Time Factors
  • Wakefulness / physiology