On Tuesday, U.S. News and World Report released its annual public high-school rankings, with the School for the Talented and Gifted in Dallas earning the top spot for the fifth year in a row. The rankings are based on a wealth of data, including graduation rates and student performance on state proficiency tests and advanced exams, as well as other relevant factors—like the percentage of economically disadvantaged students the schools serve. But there’s one key metric that isn’t tracked despite having a proven impact on academic performance: school start times.

First-period classes at the School for the Talented and Gifted start at 9:15 a.m. That’s unusually late compared to other schools but is in keeping with the best practices now recommended by public health experts.

Teens require more sleep than adults and are hardwired to want to sleep in. Eight hours a night may be the goal for adults, but teens need between 8.5–9.5 hours, according to the American Academy of Pediatrics. Unfortunately, few teens meet that minimum: Studies show that two out of three high school students get less than eight hours of sleep, with high school seniors averaging less than seven hours.

Sure, kids could go to bed earlier. But their bodies are set against them: Puberty makes it hard for them to fall asleep before 11 p.m. When combined with too-early start times, the result is sleep deprivation.

While body clocks may be hardwired, school start times are not. In the last two years, both the AAP and the Centers for Disease Control and Prevention have grown so alarmed about teen sleep deficits that they are urging middle schools and high schools to shift start times to 8:30 a.m. or later.

The side effects are severe: Sleep-starved teens are more likely to misbehave, be tardy for class, and underperform academically. They’re also more likely to be overweight, suffer from depression, drink alcohol and use drugs, and get in more car accidents. Moreover, their sleep habits now raise their risk later in life for diabetes, cardiovascular disease, and even Alzheimer’s.

Unfortunately, the CDC’s most recent report showed that nationally, less than 20 percent of middle and high schools had start times of 8:30 a.m. or later. The average? 8:03 a.m.

This average masks some of the pain. In my district, the middle schools begin at 8:45 a.m. but the high schools, including the one where my son is a student, start at 7:30 a.m.

It’s true that altering middle-school and high-school start times often presents a few major hurdles for school districts: Bus schedules and athletic programs must be retooled, and resistance to change from parents, coaches and others must be overcome. And yet districts from Seattle to Cape Cod, Massachusetts, are doing it. In fact, Seattle will be the largest district to date to make the shift, which will take effect this fall.

More important, the potential longterm gains—students who are well-rested and better performing—far outweigh the short-term logistical headaches. Even school athletics stand to benefit, given that sleep deprivation drags down peak physical performance.

Until schools make these shifts, kids will be forced to do what they can to feel less drowsy, like sleeping in on weekends to try to make up for sleep lost during the week. Unfortunately, a teen sleep study published last month showed that this strategy doesn’t work. Instead, the researchers found even two nights of recovery sleep do not undo some of the many cognitive impairments caused by just one week of partial sleep deprivation.

Other teens load up on caffeine before class. Earlier this spring, a new Starbucks opened a block from my son’s high school. On school days, there’s a pre–7:30 morning rush. It’s mostly teens.

There are doubtless many reasons why the School for the Talented and Gifted landed in the top spot—for the fifth straight year—in the U.S. News and World Report rankings. That its start time allows students to get a good night’s sleep is likely just a part of the equation—but it’s one that we can easily implement elsewhere. Our students deserve it.