IT’S Monday morning, and you’re having trouble waking your teenagers. You’re not alone. Indeed, each morning, few of the country’s 17 million high school students are awake enough to get much out of their first class, particularly if it starts before 8 a.m. Sure, many of them stayed up too late the night before, but not because they wanted to.

Research shows that teenagers’ body clocks are set to a schedule that is different from that of younger children or adults. This prevents adolescents from dropping off until around 11 p.m., when they produce the sleep-inducing hormone melatonin, and waking up much before 8 a.m. when their bodies stop producing melatonin. The result is that the first class of the morning is often a waste, with as many as 28 percent of students falling asleep, according to a National Sleep Foundation poll. Some are so sleepy they don’t even show up, contributing to failure and dropout rates.

Many of our presidential candidates have been relatively silent on how they plan to save our troubled education system. For those still searching for a policy that might have a positive impact, here’s an idea: stop focusing on testing and instead support changing the hours of the school day, starting it later for teenagers and ending it later for all children.

Indeed, no one does well when they’re sleep-deprived, but insufficient sleep among children has been linked to obesity and to learning issues like attention deficit/hyperactivity disorder. You’d think this would spur educators to take action, and a handful have.