When the Bell Tolls - The Effects of School Starting Times on Academic Achievement

Sep 14, 2026

A number of high schools across the United States have shifted to later bell times, motivated by concerns that early schedules misalign with adolescents’ biological clocks. The study evaluates whether such changes improve academic performance using individual ACT test score data for students in the Twin Cities metro area between 1993 and 2002. It also uses school-level starting-time and statewide standardized test data from Kansas and Virginia. Results show no effect on achievement, confirmed through robustness checks.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages29

Reading Time1 h 13 min

AccessFree to download

Abstract

Introduction

Motivation for later school starting times

Twin Cities comparison and identification strategy

When the Bell Tolls: The Effects of School * Starting Times on Academic Achievement Peter Hinrichs† First Draft: September 1, 2009 This Draft: July 23, 2010 Abstract: A number of high schools across the United States have moved to later bell times on the belief that their previous bell times were too early for the“biological clocks” of adolescents. This paper studies whether doing so improves academic performance. I first focus on the Twin Cities metropolitan area, where Minneapolis and several suburban districts have made large policy changes but St. Paul and other suburban districts have maintained early schedules. I use individual-level ACT test score data on all individuals from public high schools in this region who took the ACT between 1993 and 2002 to estimate the effects of school starting times on ACT scores. I then employ school-level data on starting times and test scores on statewide standardized tests from Kansas and Virginia in order to estimate the effects of bell times on achievement for a broader sample of students. The results do not suggest an effect of school starting times on achievement. This finding is unchanged by numerous robustness checks, and the Minnesota results are especially precise. Keywords: academic achievement, education policy, school starting times JEL Classification: I21, I28 * I thank Joshua Angrist, Duncan Chaplin, David Figlio, Nora Gordon, William Gormley, Daniel Hamermesh, Andrew Healy, Heinrich Hock, Harry Holzer, and two anonymous referees for helpful suggestions and discussions. I also thank lunch seminar participants at Georgetown University; seminar participants at Mathematica Policy Research; and conference participants at the 2010 American Education Finance Association, Eastern Economic Association, and Midwest Economics Association conferences. I thank Mohamad Alloush, Ryan Greenfield, and especially Thomas McCall for indispensable research assistance. I thank Eric Peterson, David Shawver, and Robert Ziomek at ACT, Inc.; and Tiffany Ellerman and Joycelyn Parish from the Kansas State Department of Education for data assistance. I also thank the 48 Minnesota school districts for agreeing to participate in the study, as well as everyone in Minneapolis Public Schools I spoke to about their policy change. I thank Georgetown University for funding.† Georgetown Public Policy Institute, Georgetown University, 3520 Prospect St NW \#308E, Washington [DC 20007. E-mail: plh24@georgetown.edu](DC 20007. E-mail: plh24@georgetown.edu) I. Introduction This paper studies a relatively inexpensive policy that may potentially raise academic achievement: moving the school day later. High school students in the United States generally begin the school day quite early. One recent random nationwide survey of schools found that the average high school began the school day at 7:54 AM in 2001- 02 (Wolfson and Carskadon 2005) . 1 At the same time, sleep scientists believe that adolescents undergo a phase shift of the sleep-wake cycle and that early school schedules are not consistent with the circadian rhythms of adolescents (Dement and Vaughan 1999) . Given the sleep habits of adolescents, it is certainly plausible that delaying the school day could increase the amount that students learn in school and consequently raise test scores. On the other hand, perhaps students are in fact able to adapt to early schedules or perhaps the later schedules chosen by some schools may still be too early. Either of these possibilities could explain why shifting the school day may not raise test scores. The possible benefits from shifting to a later school day have inspired legislation such as US Representative Zoe Lofgren’s (D-CA) ZZZ’s to A’s Act, which would encourage secondary schools nationwide to begin the school day after 9:00 AM, as well as a proposed law in Minnesota to prevent public schools in that state from beginning the school day before 8:00 AM. Although neither of those pieces of

FAQs

What policy change does the paper study?

The paper studies the effects of moving the school day later by changing high school start times.

How does the paper measure academic achievement?

Academic achievement is assessed using individual-level ACT test scores from public high schools, and statewide standardized test scores from Kansas and Virginia.

What do the results show about school starting times?

The findings indicate no meaningful effect of school starting times on academic achievement, and this result remains stable under robustness checks.

Sep 14, 2026

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