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Later middle and high school start times

Evidence Rating

Some Evidence

Health Factors

Start times for middle and high schools are typically very early, often before 8 a.m., but can be delayed via policy change, often at the school or district level. Insufficient sleep is common among US adolescents; delaying school start times substantially, until after 8:30 or 9:00 a.m., can provide an opportunity for students to get the recommended 8.5-9.5 hours of sleep on school nights (CDC-School start, ). Biological sleep-wake cycles, or circadian rhythms, shift up to two hours later for adolescents at the onset of puberty (AAP-Teen sleep 2014).

Expected Beneficial Outcomes (Rated)

  • Improved student attendance

  • Improved on-task behavior

Other Potential Beneficial Outcomes

  • Increased sleep

  • Increased academic achievement

  • Reduced motor vehicle crashes

  • Improved mental health

  • Reduced risky health behaviors

Evidence of Effectiveness

There is some evidence that delaying school start times (SSTs) for middle and high school students by an hour or more, preferably after 9 am, decreases tardiness, improves attendance, and improves on-task behavior and classroom engagement. Later SSTs have been shown to increase sleep, primarily by delaying rise times, and reduce daytime sleepiness and caffeine use among adolescents (, , , Brown 2011). Insufficient sleep is negatively associated with academic performance in middle school, high school, and college (). Additional evidence, particularly longer term studies, is needed to confirm the effects of delayed start times ().

Later SSTs can improve academic indicators such as grades or state-level test scores (, Brown 2011, , CAREI-Wahlstrom 2014, Wolfson 2007). Delayed SSTs also appear to be associated with improved concentration and ability to pay attention in class (, ). The academic effects of later SSTs appear to be stronger for students with lower levels of academic achievement and increases in reading and math scores appear larger for disadvantaged students than more advantaged students (Brookings-Jacob 2011, ). However, rigorous evaluation of these effects remains challenging since class grades are not standardized, and some standardized tests (e.g., SATs and ACTs) are not taken by all students ().

Areas with later school start times have significantly lower teen crash rates than areas with earlier school start times (, ). Later SSTs may also reduce depression symptoms and improve mood (, , ). Delayed SSTs are a suggested strategy to reduce teen engagement in risky behaviors such as alcohol or drug use and sexual activity (, CDC-School start, AAP-Teen sleep 2014).

Case studies suggest that successful efforts to implement a later SST have strong leadership, community-wide education efforts, consensus building components, and policies to support new transportation and extracurricular activity logistics (). Including education about the importance of sleep while implementing a delayed SST may increase the number of students getting more sleep and maintain initial increases over the long-term (, NSF-School start).

The cost of changing bus schedules is frequently cited as an obstacle to later SSTs; however, several school districts have realized savings in transportation costs after delaying start times (). One cost-benefit analysis of later SSTs estimates a benefit to cost ratio of 9 to 1 (Brookings-Jacob 2011).

A Kentucky-based study suggests that early elementary school start times are also associated with poorer academic performance and increased absences. Starting elementary schools earlier to delay SSTs for middle and high schools may not be beneficial ().

Impact on Disparities

Likely to decrease disparities

Implementation Examples

The Centers for Disease Control and Prevention (CDC) estimate that less than 1 in 5 middle and high schools in the US start at 8:30 am or later (CDC-School start). Most public schools start before 8:30 am. Most schools in Alaska (76%) and North Dakota (78%) start after 8:30 am, and no schools in Hawaii, Mississippi, and Wyoming start after 8:30 am (CDC-School start). As of 2014, at least 70 public school districts, approximately 1,000 schools, have implemented a delayed school start time (); 44 states have shared examples of these successful efforts (SSL-Success). 

The federal ZZZ’s to A’s Act (HR 1306) was assigned to a congressional committee for consideration in 2015. If presented to Congress and passed into law, the Act would direct the Secretary of Education to conduct a study examining the relationship between SSTs and adolescent health, well-being, and academic performance (GovTrack-HR 1306).

Implementation Resources

CDC-Sleep - Centers for Disease Control and Prevention (CDC). Sleep and sleep disorders.

NSF-School start - National Sleep Foundation (NSF). Backgrounder: Later school start times.

Citations - Evidence

* Journal subscription may be required for access.

Minges 2016* - Minges KE, Redeker NS. Delayed school start times and adolescent sleep: A systematic review of the experimental evidence. Sleep Medicine Reviews. 2016;28:82–91.

Wheaton 2016* - Wheaton AG, Chapman DP, Croft JB. School start times, sleep, behavioral, health, and academic outcomes: A review of the literature. Journal of School Health. 2016;86(5):363–381.

Owens 2014* - Owens J, Drobnich D, Baylor A, Lewin D. School start time change: An in-depth examination of school districts in the United States. Mind, Brain, and Education. 2014;8(4):182–213.

Thacher 2016* - Thacher PV, Onyper SV. Longitudinal outcomes of start time delay on sleep, behavior, and achievement in high school. SLEEP. 2016;39(2):271–281.

Edwards 2012* - Edwards F. Early to rise? The effect of daily start times on academic performance. Economics of Education Review. 2012;31(6):970–983.

Carrell 2011* - Carrell SE, Maghakian T, West JE. A’s from Zzzz's? The causal effect of school start time on the academic achievement of adolescents. American Economic Journal: Economic Policy. 2011;3(3):62–81.

Wolfson 2007 - Wolfson AR, Spaulding NL, Dandrow C, Baroni EM. Middle school start times: The importance of a good night’s sleep for young adolescents. Behavioral Sleep Medicine. 2007;5(3):194–209.

CAREI-Wahlstrom 2014 - Wahlstrom KL, Dretzke BJ, Gordon MF, et al. Examining the impact of later high school start times on the health and academic performance of high school students: A multi-site study. St. Paul, MN: Center for Applied Research and Educational Improvement (CAREI), University of Minnesota (UMN); 2014.

Brookings-Jacob 2011 - Jacob BA, Rockoff JE. Organizing schools to improve student achievement: Start times, grade configurations, and teacher assignments. Brookings Institution, Hamilton Project. 2011.

Keller 2015* - Keller PS, Smith OA, Gilbert LR, et al. Earlier school start times as a risk factor for poor school performance: An examination of public elementary schools in the Commonwealth of Kentucky. Journal of Educational Psychology. 2015;107(1):236–245.

Brown 2011 - Brown RS, Presley A, Newton L, Davison C. Eastern Commerce Collegiate Institute’s late start: Year one interim report. Toronto: Research and Information Services Department, Toronto School District Board; 2011.

Wolfson 2003b* - Wolfson AR, Carskadon MA. Understanding adolescents’ sleep patterns and school performance: A critical appraisal. Sleep Medicine Reviews. 2003;7(6):491–506.

CDC-School start - Centers for Disease Control and Prevention (CDC). Schools start too early: Starting school later can help improve an adolescent’s health, academic performance, and quality of life.

AAP-Teen sleep 2014 - American Academy of Pediatrics (AAP). Let them sleep: AAP recommends delaying start times of middle and high schools to combat teen sleep deprivation. 2014.

NSF-School start - National Sleep Foundation (NSF). Backgrounder: Later school start times.

Morgenthaler 2016* - Morgenthaler TI, Hashmi S, Croft JB, et al. High school start times and the impact on high school students: What we know, and what we hope to learn. Journal of Clinical Sleep Medicine. 2016;12(12):1681-1689.

Citations - Implementation Examples

* Journal subscription may be required for access.

Owens 2014* - Owens J, Drobnich D, Baylor A, Lewin D. School start time change: An in-depth examination of school districts in the United States. Mind, Brain, and Education. 2014;8(4):182–213.

CDC-School start - Centers for Disease Control and Prevention (CDC). Schools start too early: Starting school later can help improve an adolescent’s health, academic performance, and quality of life.

GovTrack-HR 1306 - GovTrack.us. House of Representatives congressional bill H.R. 1306: The ZZZ’s to A's Act.

SSL-Success - School Start Later (SSL). Healthy hours: Success stories.

Date Last Updated

May 25, 2017