Changing School Start Times: Impact on Student, Family, Teacher, and Community Health

The research team is conducting a multi-year, broad-based evaluation of how changing school start times impacts health and well-being for students in a diverse district in suburban Denver, Colorado. This study takes advantage of a natural experiment where the district changed school start times, with high school students starting at 8:20 a.m. (70 minutes later), middle school students starting at 8:50 a.m. (40-60 minutes later), and elementary schools starting at 8:00 a.m. (60 minutes earlier). The investigators are evaluating the impacts of the policy on the entire complex system that includes students in all grade levels, parents, school staff, and the greater community, utilizing quantitative data, contextual qualitative data, and community-based outcomes. The results of this project will be used to inform policymakers at the district, state, and national level about the community-wide impacts of changing school start times.


Shifting school start times to 8:30am or later for middle/high school students is a critical health policy that can quickly and effectively address significant adolescent sleep debt, with minimal impact on younger students, who often are required to start earlier in order to accommodate later secondary school start times.


Health: Sleep routine and schedule; diet; exercise; caffeine use; depression; anxiety; nurse-documented student health visits for sleepiness, headaches, nutrition, and stomachaches; mental health utilization of support services; motor vehicle crash rates; and pedestrian safety

Other: School attendance, tardiness, and grades


The investigators are taking a longitudinal analytic approach to compare quantitative data from before and after the policy change occurred. Data are drawn from a number of different sources, including online surveys, district information, and community statistics.  Linear mixed models are used to fit continuous outcomes, while generalized linear mixed models are used for non-normal (i.e. count or binary) outcomes. The investigators are also collecting qualitative data through open-ended survey questions and focus groups to provide additional contextual data. Registered on Open Science Framework

young teens walking down high school corridor
Grantee and Partner organizations

National Jewish Health
Cherry Creek School District

Grant status
Principal investigators
Lisa J. Meltzer, PhD
Amy Plog, PhD
Start date
Award amount
33 months

Stay Connected