California’s mandate requiring later start times for middle and high schools is yielding results, with students sleeping more, reporting better mental health and scoring higher math and English scores, according to a new study.
The new working paper from the National Bureau of Economic Research said Senate Bill 328, which went into effect in 2022, requires most middle schools to start no earlier than 8 a.m. and high schools no earlier than 8:30 a.m.
The study found that the new law increased the share of students sleeping at least eight hours per night by 13%, meeting the minimum recommended for adolescents by health experts. The largest jump was among boys.
Click Here to Subscribe to the California Political Review
The study shows that “rest and sleep are incredibly important in the function of schools,” said Osea Giuntella, an author of the report. Although the short-term increase in sleep is moderate, it has led to significant improvements in mental health and academic outcomes, he said.
Giuntella, a University of Pittsburgh researcher who studies sleep and economics, said the study’s first-year results are consistent with previous research linking better sleep to improved student well-being and academic performance. The study used changes in teachers’ commute arrival times from the American Community Survey as a proxy for later school start times, comparing sleep and mental health data before and after the law took effect in the 2022-23 school year and tracking academic gains from 2022 through 2025.
Gains in sleep, mental health, English and math
Students reported experiencing better mental health since schools shifted to later start times, with boys reporting the largest reductions in sadness, hopelessness and suicidal ideation, and Latino students reporting the biggest drop in difficulties concentrating.
Terra Ziporyn, executive director at nonprofit Start Schools Later and longtime advocate of later school start times, said the measure was a key part of California’s response to what schools have described as a student mental health crisis.
“The first step in addressing student mental health problems is to not create them in the first place,” Ziporyn said. “You can get a lot of counselors, but systematically depriving an entire adolescent population of adequate sleep is a surefire way to hurt their mental health.”
