California law improves student outcomes
California's SB 328, which required middle schools to start no earlier than 8 a.m. and high schools no earlier than 8:30 a.m. in 2022, is linked to measurable student gains, according to a National Bureau of Economic Research working paper. The study found a 13% increase in students sleeping at least eight hours, improved mental health reports—especially among boys—and academic gains in eighth grade math and English, largest for Hispanic and economically disadvantaged students. Researchers used teacher commute changes as a proxy for start times and tracked outcomes through 2025; implementation challenges and district costs remain immediate consequences to monitor.
Later start times increased eight-hour sleep prevalence by 13 percent.
Context
California passed SB 328 in 2022 to require later school start times. A new NBER working paper links the change to more sleep and higher test scores. The state may collect more data and help districts next.
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