Association for Public Policy Analysis & Management

The American Academy of Pediatrics recommends that middle and high schools start at 8:30 or later, yet fewer than 15 percent of schools follow this recommendation. Estimating the benefit of a later start time has proven difficult as start times are not determined randomly. Using quasi-experimental variation embedded in the assignment process, we measure the causal impact of school starting times on student learning. Our instrumental variables strategy leverages exogenous variation arising from tie-breakers in the Deferred Acceptance algorithm. We use data on Wake County Public School System students who are entering middle school. These students may apply to magnet schools with start times ranging from 7:30am to 8:30am. For children whose counterfactual school starts the day at 7:30am, attending a magnet school that starts at 8:30am is associated with a large and statistically significant gain in reading scores. These results suggest that later school start times can substantially improve student learning.