The topic of a new course at Mansfield Senior High School is one that teenagers across the country are having trouble with: How to Get to Sleep.

One ninth grader in the class says his method is to scroll through TikTok until he nods off. Another teen says she often falls asleep while on a late-night group chat with friends. Not everyone takes part in class discussions on a recent Friday; some students are slumped over their desks napping.

Sleep training is no longer just for newborns. Some schools are taking it upon themselves to teach teenagers how to get a good night’s sleep.

“It might sound odd to say that kids in high school have to learn the skills to sleep,” says Mansfield health teacher Tony Davis, who has incorporated a newly released sleep curriculum into a state-required high school health class. “But you’d be shocked how many just don’t know how to sleep.”

Adolescents burning the midnight oil is nothing new; teens are biologically programmed to stay up later as their circadian rhythms shift with puberty. But studies show that teenagers are more sleep deprived than ever, and experts believe it could be playing a role in the youth mental health crisis and other problems plaguing schools, including behavioral and attendance issues.

“Walk into any high school in America and you will see kids asleep. Whether it’s on a desk, outside on the ground or on a bench, or on a couch the school has allotted for naps — because they are exhausted,” says Denise Pope, a senior lecturer at Stanford Graduate School of Education. Pope has surveyed high school students for more than a decade and leads parent sessions on the importance of teen sleep. “Sleep is directly connected with mental health. There is not going to be anyone who argues with that.”

Adolescents need between eight and 10 hours of sleep each night for their developing brains and bodies.

But nearly 80% of teens get less than that, according to the federal Centers for Disease Control and Prevention, which has tracked a steady decline in teen sleep since 2007.

Today, most teens average six hours of sleep.

Research increasingly shows how tightly sleep is linked to mood, mental health and self-harm. Multiple studies also show links between insufficient sleep and sports injuries and athletic performance, teen driving accidents, and risky sexual behavior and substance use, due in part to impaired judgment when the brain is sleepy.

For years, sleep experts have sounded an alarm about an adolescent sleep crisis, joined by the American Medical Association, the American Academy of Pediatrics, the CDC and others. As a result, some school districts have shifted to later start times. But simply telling a teenager to get to bed earlier doesn’t always work, as any parent can attest.

That’s why Mansfield City Schools, a district of 3,000 students in north-central Ohio, is staging what it calls “a sleep intervention.”

The district’s high school is piloting the new curriculum, “Sleep to Be a Better You,” hoping to improve academic success and reduce chronic absences. Surveys of parents and students highlighted widespread problems with sleep and an intractable cycle of kids going to bed late, oversleeping, missing the school bus and staying home.

The students in Davis’ classroom shared insights into why it’s hard to get a good night’s sleep.

An in-class survey of the 90 students across Davis’ five classes found over 60% use their phone as an alarm clock. Over 50% go to sleep while looking at their phones.

During the six-part course, students are asked to keep daily sleep logs for six weeks and rate their mood and energy levels.

Freshman Nathan Baker assumed he knew how to sleep but realizes he had it all wrong. Bedtime meant settling into bed with his phone, watching videos on YouTube or Snapchat Spotlight and often staying up past midnight. On a good night, he got five hours of sleep. He’d feel so drained by midday that he’d get home and sleep for hours, not realizing it was disrupting his nighttime sleep.

“Bad habits definitely start around middle school, with all the stress and drama,” Baker says. He has taken the tips he learned in sleep class and been amazed at the results. He now has a sleep routine that starts around 7 or 8 p.m.: He puts away his phone for the night and avoids evening snacks, which can disrupt the body’s circadian rhythm. He tries for a regular bedtime of 10 p.m., making sure to close his curtains and turn off the TV. He likes listening to music to fall asleep but has switched from his previous playlist of rousing hip-hop to calmer R&B or jazz, on a stereo instead of his phone.

“I feel a lot better. I’m coming to school with a smile on my face,” says Baker, who is averaging seven hours of sleep each night. “Life is so much more simple.”

There are scientific reasons for that. Studies with MRI scans show the brain is under stress when sleep-deprived and functions differently. There is less activity in the pre-frontal cortex, which regulates emotions, decision making, focus and impulse control; and more activity in the emotional center of the brain, the amygdala, which processes fear, anger and anxiety.

Parents and teens often aren’t aware of the signs of sleep deprivation, so they attribute it to typical teen behavior: being irritable, grumpy, emotionally fragile, unmotivated, impulsive or generally negative. Think of toddlers who throw temper tantrums when they miss their naps.

“Teenagers have meltdowns, too, because they’re tired. But they do it in more age-appropriate ways,” says Kyla Wahlstrom, an adolescent-sleep expert at the University of Minnesota who has studied the benefits of delayed school start times on teen sleep for decades. Wahlstrom developed the free sleep curriculum being used by Mansfield and several Minnesota schools.

Social media has been blamed for fueling the teen mental health crisis, but many experts say the national conversation has ignored the critical role of sleep.

Nearly 70% of Davis’ students said they regularly feel sleepy or exhausted during the school day. But technology is hardly the only reason. Today’s students are overscheduled, overworked and stressed out, especially as they get closer to senior year and college applications.

Chase Cole, a senior at Mansfield who is taking three Advanced Placement and honors classes, is striving for an athletics scholarship to play soccer in college. He plays in three soccer leagues and typically has practice until 7 p.m., when he gets home and needs a nap. Cole wakes up for dinner, then dives into homework for at least three hours. He allows for five-minute phone breaks between assignments and winds down before bed with video games or TV until around 1 a.m.

“I definitely need to get more sleep at night,” says Cole, 17. “But it’s hard with all my honors classes and college stuff going on. It’s exhausting.”

There aren’t enough hours in the day to sleep, says sophomore Amelia Raphael, 15. A self-described overachiever, Raphael is taking physics, honors chemistry, algebra and trigonometry, and is enrolled in online college classes. Her goal is to finish her associate degree by the time she graduates high school.

“I don’t want to have to pay for college. It’s a lot of money,” says Raphael, who plays three sports, is on student council and in other clubs, and gets to bed between midnight and 2 a.m.

She knows she’s overscheduled. “But if you don’t do that, you’re kind of setting yourself up for failure. There is a lot of pressure on doing everything. I am giving up sleep for that.”