A teenager’s slow crawl out of bed to start the school day is a long tradition. But increasingly the science is telling us that it’s not laziness, rebellion or teenage angst that’s the cause. It’s biology.

Teenagers need more sleep than adults, and early start times for school aren’t helping. The American Academy of Pediatrics recently began to advocate for starting high school at 8:30 a.m. in hopes of better meeting students’ sleep needs. This could also help combat depression, reduce car accidents and help with other health problems that can arise from insufficient sleep, the Academy said.

While acknowledging that there are other factors, starting high school before 8:30 a.m. is “a key modifiable contributor to insufficient sleep, as well as circadian rhythm disruption, in this population,” the Academy said in an August policy statement.

Other children’s health advocates are also weighing in. From a Yale YouTube video to the CDC, experts are calling for later start times.

The problem is that the recommendation doesn’t line up with most school schedules. And making changes to a high school schedule is the equivalent of rearranging the daily workings of a small city, educators say.

Early hours await California students

Many California schools start before 8 a.m., with an even earlier arrival time for those taking “zero period,” which is when many elective or advanced classes are offered. In some cases, like at Clovis East High School in the Central Valley, the start time of such classes is 6:40 a.m.

It’s an issue that parents deal with across the state. Irena Keller, an associate professor at San Jose State University, has a daughter in high school and a son in middle school. Her daughter takes honors classes, which can mean a zero period start time — before 7 a.m. Her son must also rise early to attend orchestra practice before regular classes begin.

The problem for her children, and others who attend California schools, is that their bodies are telling them to get anywhere from eight and a half to nine hours of sleep a night. Being jolted out of bed before the sun rises doesn’t match up with their circadian rhythm, Keller said.

“When teenagers have to wake up at 6 for school, it’s as if you’re waking up at 5 or even 4,” she said. “It’s not natural and they don’t complete the whole sleep cycle. Teens as a group are the most sleep deprived, and it’s because the school’s schedule is not synchronized with their biological schedule and an early start makes them wake up before they compete all the stages of sleep they need.”

The cycle of insufficient sleep

Keller said that research on teenage sleep matches her experience with her own children. Her son was an early riser as a young child, waking up the whole house. But now in the teenage years, he’s an extreme night owl. It’s a similar situation with her daughter, who tries to go to sleep early, puts away her electronic devices, but still stares at the dark ceiling and is unable to go to sleep at the hour needed to give her enough sleep for her early arrival time at school.

Part of the problem is that, as students get insufficient sleep, they tend to wake up at the wrong time in their sleep cycle. Mariana G. Figueiro, who studies the impact of light upon sleep at the Lighting Research Center, said such inconsistency can wreak havoc on the body’s natural patterns.

“Waking up at the end of REM (rapid eye movement) is actually when you wake up more rested,” she said. “If it’s in the middle of the REM or another of the non-REM cycles you’re going to wake up groggy.”

Parents who want to encourage their students to get more sleep should know that exposure to smartphones, tablets and other electronics as a light source can inhibit the production of melatonin, a chemical the body releases in the evening that tells you it’s time to sleep.

California schools inch towards changes

According to Matt Best, the Associate Superintendent of Administrative Services for the Davis Joint Unified School District, while the research regarding teenage sleep is compelling, making wide-scale changes that doesn’t disrupt the other workings of a school is another matter.

“You’re working against cultural norms and a bureaucratic system that is in place for good reasons, but you have to be thoughtful about the process and discussions.”

Because of the research on teenage sleep, some California high schools are starting to make changes. The Davis Joint Unified School District, for example, is switching its middle schools to an 8:30 a.m. start time at the start of the 2016-17 school year. The district’s later start initiative was driven by the school board’s interest in the growing medical evidence in support of later start times.

Maria Clayton, spokeswoman for the district, said the current effort is to move Davis Senior High School to an 8:30 a.m. start time in the fall of 2017. However, it’s not as simple as just adjusting the entire schedule down an hour, she said.

A high school has to consider sports practices, multiple co-curricular activities and coordination with other schools. The goal is to move back the time without significantly extending the school day. Finding places to squeeze out minutes without throwing off the entire schedule is the challenge.

“We’re looking at creative scheduling with blocks so they can work in that kind of structure that’s needed,” she said. “It’s a large campus, with a lot of classes that are offered there, so it’s something they have to look at and weigh carefully. That’s the objective and the course of this next year is to get us there.”

Other schools have already made the change: Gunn High School in the Palo Alto Unified School District moved its start times to 8:30 a.m. in 2012. There’s still talk about how to manage early class periods, which are still a fact of life for high schools that want to provide additional advanced classes or co-curricular activities.

Keller said she hopes more high schools in the state will change their start times soon.

“When kids are able to come to school later, then they actually get more sleep. They wake up later and are more refreshed. That’s why the results are good for the schools and the students. We see big changes in grades, performance, less anxiety, depression, suicides and car accidents,” she said.