Study Snapshot: Students Enrolled in Late-Start-Time Districts Report Higher Academic Achievement and Sleeping More

For Immediate Release: April 10, 2021

Tony Pals,
(202) 238-3235, (202) 288-9333 (cell)

Tong Wu,
(202) 238-3233, (202) 957-3802 (cell)

Study Snapshot: Students Enrolled in Late-Start-Time Districts Report Higher Academic Achievement and Sleeping More

Study: “Students Enrolled in Late-Start-Time Districts Report Higher Academic Achievement and Sleeping More"
Authors: Julio Caesar (Bloomington Public Schools), Rik Lamm (University of Minnesota), Michael C. Rodriguez (University of Minnesota), David J. Heistad (Bloomington Public Schools)

This study will be presented today at the AERA 2021 Annual Meeting.
Session: Organizational Effects Examining Academic Achievement and Student Support
Date/Time: Saturday, April 10, 2:30 p.m. - 4:00 p.m. ET

Main Finding:

  • Later school start times are linked to higher grade point averages and higher proportions of students getting the recommended number of hours of sleep.


  • The authors note that there is currently a large push across the country from researchers and public health experts for delayed or later school start times. According to the Centers for Disease Control and Prevention, the average start time in the United States was 8:03 a.m. in the 2011–12 school year. The majority of schools (76 percent) had a start time between 7:30 a.m. and 8:29 a.m. and only 18 percent of schools had a start time after 8:30 a.m.
  • Although prior research has shown that getting more sleep at night results in reduced daytime sleepiness, improved motor functioning, improved reaction time, and better mental health, previous research on the effects of delaying school start times on academic outcomes is limited and their findings were mixed.
  • For their study, the authors analyzed data from the 2016 and 2019 Minnesota Student Survey, which is administered in schools in grades 5, 8, 9, and 11. Four school districts were identified as transitioning from an early to late start time between the 2016 and 2019 administrations.
  • These four districts transitioned from start times of 7:25 a.m., 7:30 a.m., 7:33 a.m., and 8:10 a.m. to 8:35 a.m., 8:20 a.m., 8 a.m., and 8:30 a.m., respectively. The authors compared these districts to four other early-start-time school districts that closely matched the transitioned districts on measures of student race/ethnicity, English learner status, special education participation, and free- or reduced-priced lunch status. Data from a total of 38,019 students from these eight districts were analyzed.
  • The authors found that students in school districts that moved to a later start time reported higher grade point averages and higher proportions of meeting the recommended hours of sleep in 2019, after controlling for sociodemographic variables and students’ self-reported commitment to learning (a measure composed of caring about doing well in school, paying attention in class, going to class prepared, and being interested in learning).
  • The authors found a small increase in average GPA—0.14—in the school districts with delayed start times over those school districts that kept early start times. Overall, predicted GPA increased for all grades for the school districts with delayed start times, ranging from 0.10 to 0.17 GPA points.
  • “Although the change to a later start time had a small effect on GPAs, it is still meaningful for every student whose grades were helped by only the policy decisions of district leaders,” said coauthor Rik Lamm, a doctoral student at the University of Minnesota.
  • The study findings indicate that pushing back start times made a difference in the number of hours students slept. The odds of students meeting the recommended number of hours of sleep—nine or more for students in grades 5 and 8, and eight or more for students in grades 9 and 11—increased by 16 percent for students in districts with delayed start times from 2016 and 2019, compared to no change for the early-start-time school districts.
  • “These findings, together with the positive physical health and mental health outcomes found by other colleagues, will provide school districts additional insight to guide them in making appropriate decisions about school start-time changes,” said coauthor Julio Caesar, research scientist in the evaluation and assessment department at Bloomington (MN) Public Schools.
  • The authors added that school start-time changes have been reported to result in short-term as well as long-term financial savings. “At a time when school budgets are tight, this is an inexpensive option to increase academic outcomes as well as the physical and mental health of students that’s fairly easy to implement,” said Caesar.

To request a copy of the working paper, or to talk to study authors, please contact AERA Communications: Tony Pals, Director of Communications,, cell: (202) 288-9333; Tong Wu, Communications Associate,, cell: (202) 957-3802


About AERA
The American Educational Research Association (AERA) is the largest national interdisciplinary research association devoted to the scientific study of education and learning. Founded in 1916, AERA advances knowledge about education, encourages scholarly inquiry related to education, and promotes the use of research to improve education and serve the public good. Find AERA on FacebookTwitter, and Instagram.