California’s Later School Start Times Are a Promising Experiment

California high schoolers returning to class can look forward to a welcome back-to-school gift: more time to sleep. A new state law will require that public high schools start classes no earlier than 8:30 a.m., a half-hour later than the national average. The shift has the potential to improve students’ mental health and academic performance — so long as schools commit the time and money necessary to make it work.

For much of the 20th century, schools opened their doors at 9 a.m., in line with most businesses. Yet today, more than 80% of high schools in the U.S. start before 8:30 a.m., and nearly half before 8 a.m. — a norm dictated by convenience more than pedagogy. Pushing up start times for older students allows school districts to save on transportation costs by running staggered bus schedules. It also means an earlier end to the school day, leaving sufficient daylight for non-academic activities, particularly organized sports.