The last students around the country are making their way back to school this week. But regardless of the virtues of starting a new school year in August or in September, one thing is still almost uniformly true: Most of the nation’s public middle schools and high schools still start far too early—in the morning, that is. The latest data, part of the 2015–2016 National Teacher and Principal Survey (conducted by the U.S. Department of Education’s National Center for Education Statistics), show an average high-school start time of 7:59 a.m. and an average middle-school start of 8:04 a.m. That’s unchanged from the previous NCES survey for the 2011–2012 school year—and much earlier than the 8:30 a.m. start time recommended by the American Academy of Pediatrics, and others, based on the myriad health and academic risks too-early start times pose.

It isn’t that these recommendations aren’t well-known. Overall, though, changing school start times—and changing public opinion—has been slow. For one thing, teens are often still seen as the root cause of their own chronic sleepiness. As a parent volunteer who’s been advocating for healthy start times as part of Start School Later California, I spend a lot of time answering questions like, “Why can’t teens just go to bed earlier?” The answer? Kids’ body clocks shift when they hit adolescence, making it harder for them to fall asleep until about 11 p.m. They can’t get the recommended 8.5–9.5 hours of sleep their growing bodies need if they have to wake at dawn because of too-early start times.

Others see the current start times as good practice for the real world. As one commenter noted on a Slate article I wrote on the topic: “Most workplaces expect you to set your alarm, get up in the morning, and haul you’re a$$ to the office on time, despite the urgings of your circadian rhythms.” But this ignores the reality that there isn’t actually a uniform start time for work, and that adults need less sleep than teens.

Still others think that just getting teens to use their smartphones less at night might help them get more sleep.

“No one is arguing that there aren’t multiple causes of adolescent sleep loss,” says Wendy Troxel, a senior behavioral and social scientist at the RAND Corp. “However, school start times are the only policy-level issue that has been identified as directly contributing to the problem. Certainly addressing individual factors such as technology use and blue light is important, but we know from a significant amount of research that solely addressing major public health issues via individual-level interventions is not sufficient to solve the crisis.”

Troxel cites efforts to combat obesity as an example, noting that while encouraging individual-level behavior such as eating more fruits and vegetables and fewer processed foods has had an impact, stemming the nation’s rising obesity levels ultimately requires broader actions such as targeting soft-drink consumption.

The shift to later start times has been gathering momentum since 1996, when Edina, Minnesota, became the first district in the nation to switch its start times based on the research, and the pace has increased markedly in the last few years. In 2014, the American Academy of Pediatrics issued its landmark policy statement, noting that “the average adolescent in the United States is chronically sleep deprived and pathologically sleepy.” The following year, the Centers for Disease Control and Prevention released the first-ever federal recommendation on school start times, underscoring that school start times are a public health issue and should be treated as such.

About 400 districts around the country have made the shift to date, with schools in at least 19 states doing so this year. But that still leaves too many schools that start too early: 87 percent of the nation’s public high schools and 81 percent of middle schools, according to the 2015–2016 data.

Many schools recognize the validity of the research and evidence but still find the change to be burdensome. But soon they may have to take the plunge: In California, for example, pending legislation could require a minimum 8:30 a.m. start time for the state’s public middle and high schools. The bill, introduced by state Sen. Anthony Portantino, D–La Cañada Flintridge, has already passed the state Senate and will be voted on by the state Assembly in the next couple of weeks. It would give schools until July 2020 to make the change—providing nearly three years for them to address logistics and other related concerns.

If California passes this legislation, it may well set the standard for other states to follow. And if not, we shouldn’t be surprised if the next report again shows that we still aren’t doing enough for our pathologically sleepy teens.