California鈥檚 mandate requiring later start times for middle and high schools is already 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 from the National Bureau of Economic Research examines the effects of Senate Bill 328, California鈥檚 statewide mandate for later school start times. The law, 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 . The largest jump was among boys.

The study shows that 鈥渞est and sleep are incredibly important in the function of schools,鈥� 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鈥檚 first-year results are consistent with previous research linking better sleep to improved聽student well-being and academic performance. The study used changes in teachers鈥� 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 SB 328 took effect in the 2022-2023 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 Hispanic 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 SB 328 was a key part of California鈥檚 response to what schools have described as a student mental health crisis.

鈥淭he first step in addressing student mental health problems is to not create them in the first place,鈥� Ziporyn said. 鈥淵ou 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.鈥�

The study also found significant improvements in academic achievement, with eighth grade students making measurable gains in math and English, particularly among Hispanic and economically disadvantaged students.

Giuntella, the study鈥檚 author, said the improvement in scores was likely 鈥渓argely driven by the change in sleep鈥� based on comparable where increased sleep led to higher GPAs. That鈥檚 also why Hispanic students, who are already less likely to get adequate sleep than white students due to lower family income and family and work responsibilities, improved their math and English scores the most, Giuntella said.

Parents struggle with new schedules

The state mandate is the only one in the nation.

鈥淐alifornia set a huge precedent for the whole nation by saying, 鈥榃e cannot leave what is essentially a public health decision in the hands of local districts,鈥� 鈥� Ziproyn said. 鈥淚t鈥檚 not just a negotiable school budget item that you trade off against anything else.鈥�

But some parents have said later start times complicate work commutes, push back sports and extracurricular activities and lead to some students simply pushing back the time they go to bed.

The study found that sports and extracurricular activities did start later after the change to later start times, but the changes were 鈥渕arginal and not statistically significant,鈥� Giuntella said.

鈥淎nd it鈥檚 true that, yes, students may even go to bed a little later than they were, but they are definitely sleeping in more in the morning,鈥� she said.

Guintella described later start times as just 鈥渙ne institutional factor鈥� that may help address a complex sleep-deprivation problem, pointing to issues like the rise in nighttime screen use.

鈥楾oo hard and too expensive鈥� for some districts

Some school districts found the transition to later school start times 鈥渢oo hard and too expensive,鈥� Ziporyn said. Ziporyn said district administrators could have received more guidance from the state Department of Education to explain the benefits of later start times, and involve families in finding solutions to logistical problems.

鈥�(Schools) have to fully understand why this is being done and communicate it with confidence to the community that they鈥檙e doing the right thing for kids,鈥� Ziporyn said.

San Francisco Unified, for example, worked with operations experts at the Yale School of Management, Georgia Tech University and Northwestern University to redesign their bus routes in response to the change. With more than 120 schools and 18 different start times, the district generated about 1,000 new feasible bus schedules, which ended up saving the district about $5 million and with a majority of families and staff members satisfied with the transition to later start times, according to a report by

But most schools in California did not have access to dedicated consultants to ease the transition, Ziporyn said.

鈥淐alifornia could have improved making these resources more readily available to the districts,鈥� Ziporyn said. 鈥淏uilt into the law was that there was supposed to be help from the state Department of Education about getting this done, and building that community buy-in is part of it.鈥�

Giuntella said the state can improve its implementation of SB 328 by collecting statewide data on later school start times to 鈥渁ssess the impact of the reform.鈥� In the meantime, schools can take from the study that later start times are 鈥渆ffective and powerful tools鈥� for student outcomes.

鈥淭his happens often with some shock to individual and families鈥� habits, and so it also requires the ability to navigate this transition in a way that doesn鈥檛 backfire,鈥� Giuntella said.

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California and Florida have become the first states to require later public school start times, a response to reams of research showing significant advantages for high school students who can get more sleep by beginning their day at 8:30 a.m. or later.

But such changes come with difficult ripple effects 鈥� upended bus schedules, later starts for extracurriculars and new schedules for teachers and staff 鈥� making many other states and localities hesitant to change.

California鈥檚 first-in-the-nation law, which requires that high school classes start no earlier than 8:30 a.m. and middle schools not before 8 a.m., took effect last school year. Florida overwhelmingly passed a law this year with similar requirements, which schools must meet by July 2026.

But similar efforts in other states have stalled or been reduced to legislation calling for studies of the issue, in the face of opposition from local school districts worried about budgets and parents concerned about upending family schedules. Lawmakers in Connecticut, Maine, Massachusetts, New Jersey, New Mexico, New York, Oregon and Texas all had bills up this year, according to Start School Later, an advocacy group that tracks the bills. But most didn鈥檛 pass; Maine, Maryland and Indiana approved studies, the group said.

鈥淭he fact that Florida passed it is a game changer; it shows this really is a bipartisan issue,鈥� said Terra Ziporyn Snider, the group鈥檚 executive director and co-founder. There has been legislation proposed in 25 states, she added, but getting these bills through legislatures won鈥檛 be easy.

Florida state Rep. John Temple, a Republican who sponsored his state鈥檚 measure, told the House Education and Employment Committee in March that when teenagers don鈥檛 get enough sleep, their health, safety and academics all suffer, and he noted a requirement for local input. The new law requires district school boards to 鈥渄iscuss local strategies to successfully implement the later school start times.鈥� The measure passed on overwhelmingly bipartisan votes.

But Florida state Rep. Patricia Hawkins-Williams, a Democrat who voted against the measure, said she was concerned about costs, especially for smaller school districts. The issue for many school districts is that allowing high schools to start closer to elementary and middle school start times means running more buses. The legislature set aside $5 million to plan, implement and evaluate the new start times, but Hawkins-Williams said she worries districts will be on the hook after that initial money runs out.

鈥淲hile the students are going back and forth [on buses to school], it鈥檚 the responsibility of the districts and it will increase the cost to the district and is a recurring cost every year,鈥� she said in an interview with Stateline. 鈥淭he state often puts these things together and pushes them down to the local school districts.鈥�

She said she understood the studies about the benefits to kids but added, 鈥淭he cost outweighed the benefits.鈥�

Studies agree on later starts

The average start time for public high schools was 8 a.m. during the 2017-2018 school year, according to by the National Center for Education Statistics published in 2020, the latest year for which the federal agency has comprehensive statistics.

But Kyla Wahlstrom, a senior research fellow and lecturer at the University of Minnesota, estimates that 1,000-2,000 individual school districts across the country, as well as the two states, have recently moved high school start times to approximately 8:30 a.m. That鈥檚 the earliest start time recommended for high schools and middle schools by the American Medical Association.

Numerous studies have concluded that the later start times are healthier for kids, reduce juvenile crime, improve grades, boost sports performance and even result in better teenage driving records, because sleepy teens cause more accidents.

The federal Centers for Disease Control and Prevention of sleep is 鈥渃ommon鈥� among high school students and is associated with increased risk of being overweight, drinking, smoking, using drugs and poor academic performance. The American Academy of Pediatrics recommends that high schools not start before 8:30 a.m., and says changing to later start times would result in better outcomes for teens, including reduced obesity risk, lower rates of depression, fewer drowsy driving crashes and improved quality of life.

The  recommends that kids 13-18 should sleep eight to 10 hours a day. The policy statement says adolescents of those ages have circadian rhythms that prevent them from falling asleep earlier in the evening. And a study by the Rand Corporation found that the economic benefit of later school start times 鈥渨ould outweigh the costs within five years after the change鈥� in the vast majority of states, mostly due to less use of mental health facilities and juvenile judiciary and detention.

But changing school start times affects more than just the students. After-school activities start later too, reducing teens鈥� availability for part-time jobs. Parents鈥� work schedules must be adjusted. Traffic patterns also shift, due to school bus schedules and associated crosswalk delays.

鈥淐ommunity life does revolve around school hours,鈥� said Start School Later鈥檚 Ziporyn Snider. 鈥淭his is why it鈥檚 so important to do it legislatively. It鈥檚 so hard to do at the local level. It鈥檚 hell on Earth dealing with people coming at you with pitchforks when you suggest changing the schedule.鈥�

California legislators first passed a bill in 2018, but then-Gov. Jerry Brown, a Democrat, vetoed it amid opposition by teachers unions and many local school districts. But by 2019, many teachers and the state PTA had come around to support the idea of later start times, and the bill was passed and signed by Democratic Gov. Gavin Newsom.

Part of the difficulty in passing the laws to change start times is a lack of education about teenagers鈥� sleep, said the University of Minnesota鈥檚 Wahlstrom, a leading expert on adolescents鈥� sleep patterns. Her seminal in 2017 noted that research as early as the 1990s showed teenagers are 鈥渦nable to fall asleep before about 10:45 p.m. and remain in sleep mode until about 8 a.m.鈥�

Of the more than 9,000 students who participated in the University of Minnesota study, those who slept eight or more hours each night were less likely to report symptoms of depression and to fall asleep in class. And the number of car crashes in the districts studied decreased by 13%.

鈥淚t鈥檚 about educating parents and teens, that they will look better and do better in school, and do better in sports if they will go to bed at 11:15 and get up at 7:30,鈥� Wahlstrom said in an interview with Stateline. Parents should also take cellphones and other electronic devices away after 11 p.m., she said.

Concerns in other states

Sometimes new start times come with a few hiccups.

In Howard County, Maryland, an affluent public school district with about 57,000 students, new start times, combined with a new bus company and an insufficient number of bus drivers, resulted in chaos in the opening weeks of class last month. Some buses never showed up or were hours late, leaving kids stranded. A new app that was supposed to allow parents to track bus whereabouts failed, leaving parents furious.

In response to queries from Stateline, Brian Bassett, spokesperson for Howard County schools, said district administrators were not aware until the first day of school in late August that all the routes were not being covered by the bus company, Zum, due to lack of drivers.

In a report to the community, Superintendent Michael Martirano said the new start times鈥� effect on transportation had been studied for six months, but that they were just one of a number of factors in the bus mess.

鈥淭he compression of the start times to support our goal of starting schools later has taken out any slack that we used to have in our routes and it is not realistically possible to keep [all] buses 鈥� on schedule due to the tight turnaround,鈥� he said. Further, he said, 鈥渋t is highly likely that an adjustment to some bell times, as well as pick-up times, will be necessary to make sure ALL buses can arrive on time and students do not have to endure long wait times in the afternoon to get picked up.鈥�

In an email to Stateline, Zum, based in Redwood City, California, said almost all of the Howard County bus routes had been covered by the end of the second week but acknowledged there were still delays due to route 鈥渟tacking,鈥� in which buses drop off students at school and immediately begin another route. The company blamed Howard County for the quick-turnaround schedules, which, it said in an email, 鈥渓eave no time for our drivers to safely unload their students and begin their next route.鈥�

No system changes had been implemented as of early September.

In Maine, Democratic state Sen. Mattie Daughtry has been pressing for later school start times since she was a student at Brunswick High School, where her yearbook goal was to 鈥済et more sleep.鈥� Now age 35 and representing the town where she went to high school, Daughtry has sponsored a later start time bill for several sessions without success.

This year, she got students to testify in favor, but was met with opposition from some lawmakers and the Maine Education Association, which testified that such a change would pose 鈥渙perational and logistical challenges.鈥�

鈥淥ur schools serve students whose parents do not have the workplace flexibility for a later drop off, and their experiences and schedules must be considered,鈥� the union said in written testimony to the legislature.

But Daughtry said such concerns pale beside the advantages, including reduction in obesity rates and diabetes, and less risky behaviors when kids get more sleep. She said she understands the challenges facing working families, and called for communities to take child care needs into account.

鈥淲e need to look at everything as a whole,鈥� she said. 鈥淲e have an opioid crisis in Maine, and that decreases when folks are well rested. This will boost test scores. The opposition isn鈥檛 even partisan. It鈥檚 just a lot of folks who say, 鈥榃hen I was that age, I did [start early] in school.鈥� There鈥檚 not enough awareness of medical science.鈥�

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After long-standing research showed the devastating impact of early classes on teens鈥� health, California鈥檚 district middle schools will start no earlier than 8 am; and high schools will start no later than 8:30 am. Rural district schools are exempted from the state mandate. 

Now, New Jersey, New York, Massachusetts and the Virgin Islands legislators are now considering mandated school start time changes. 

The California , passed in 2019, was debated for its effect on all students, parents, and teachers 鈥� but not without qualms over how it would disrupt families鈥� schedules and create other problems. 

 Cindy Velasco, a working California parent with two high school kids, said she supported the later start time law for several reasons, including the difficulty of juggling dropping off her kids for early classes and getting to work on time.  

鈥淚t鈥檚 difficult for parents because our work day starts earlier,鈥� Velasco said. 鈥淗aving to take my kids to school later is difficult for me. I had to rely on my family to help my daughter get to school.鈥�

Most important, Velasco said, was the negative effect on learning she saw early classes had on her children.  

Researchers who have been investigating the issue for years agree. 

鈥淭he school start time, when it’s early, is crushing adolescent sleep,鈥� said Mary Carskadon, director of sleep research and chronobiology at Bradley Hospital in Rhode Island.

鈥淲hen school starts very early, they [early teenagers] end up kind of stuck because they are biologically unable to sleep early,鈥� said Carskadon, who has studied sleep and circadian rhythms for decades.

鈥淚f they have to get up at 5:30 to 6 a.m. to go to school, they can鈥檛 fall asleep at 9 or 10 p.m. to get even 8 hours of sleep, which isn鈥檛 enough sleep for these early teenagers.鈥�

Kyla Wahlstrom, a professor of education administration policy at the University of Minnesota, who  researches school start times, said the brains of kids who are getting up as early as 6:30 a.m. to get to school starting at 8 a.m. 鈥渁re still in sleep mode.鈥� 

鈥淭here鈥檚 all this constellation of good outcomes 鈥� less depression, less drug use, less cigarette and alcohol use, less premarital sex鈥hen there is a later starting time for the students to get to school, which gives them more sleep in the morning,鈥� Wahlstrom said, adding other outcomes, including performing better at school and involved in less car accidents.

Troy Flint, the chief information officer of the California School Boards Association, said the CSBA opposed the law when it was being debated in the state legislature, in part, because of the 鈥渢remendous hardship for many families that had inflexible work schedules or that needed the student to work for financial reasons 鈥� siblings who have childcare responsibilities.鈥�

Flint said the California School Boards Association, which represents about 900 schools districts and county offices of education in California, did not oppose the law to change school start times 鈥渋n concept.鈥�

鈥淲hat we opposed was the universal mandate which required every school district to adopt the law regardless of individual situation,鈥� Flint said.

Research on school start times 鈥� and their effect on students 鈥� started in the 1990s as school districts across the country implemented later classes. 

Earlier this year, New Jersey State Senator Vin Gopal (D) and Assemblyman Craig J. Coughlin (D) introduced two in the Legislature to move the start times for high schools no earlier  than 8:30am beginning in the 2024-25 school year. 

 鈥淭here鈥檚 no real timeline. We鈥檙e still having conversations with stakeholders,鈥� said Gopal鈥檚 policy director Micharel Illiano. 鈥淲e are trying to make sure we are being cautious and responsible and not moving too quickly.鈥�

 New Jersey School Boards Association spokesperson Janet Bamford said the organization does not support a state mandate for school start times, and that the decision should be made locally because of the 鈥渉urdles to implementing later start times.鈥�

Bamford cited 鈥渢he potential for increased transportation costs, difficulty in scheduling after-school activities, unintended impacts on other students 鈥� particularly elementary school children 鈥� and programs, and disruption to family schedules.鈥� 

In New York, State Assembly member Harvey Epstein and State Senator Robert Jackson in 2021 that would require all New York state public schools to start no earlier than 8:30 a.m.

鈥淭he bill is taking a long time 鈥� I don鈥檛 know the timeline鈥� said Epstein. 鈥淭his is a conversation around health and safety because we know the science, the medical data is there, and I think we need to educate people about how important it is.鈥�

Massachusetts and the are also considering state mandated later school start times.