Vast majority of teens are sleep-deprived

Most adolescents can get by with at least eight hours of zzzzz’s a night, studies show, but ideally should garner at least nine. A new study tells us just how many kids meet their ideal slumber quota: a whopping 7.6 percent.

The number comes from a tiny paper published early online, this week, in the Journal of Adolescent Health. Danice Eaton led a research team at the Centers for Disease Control and Prevention that surveyed a statistically representative sample of more than 12,000 U.S. high school students. They probed a range of issues as part of a Youth Risk Behavior Surveillance. Among those questions: “On an average school night, how many hours of sleep do you get?”

Roughly one-quarter of the kids fell into the borderline-acceptable category, meaning they reported eight hours of shuteye nightly. The overwhelming majority fell short — with 30.2 percent reporting seven hours, 22.8 percent slumbering closer to six hours, 10 percent catching a mere five hours of sleep, and 5.9 percent claiming to nod off for no more than four hours most weeknights. Just the thought makes me yawn.

What the study didn’t explore is why kids aren’t sleeping enough. Certainly, schools don’t help the situation by starting classes earlier for teens than they do for younger kids — even though puberty and other developmental changes lead to adolescents needing more sleep than grade schoolers, not less.

But there could be other issues.

Like what share of teens don’t get enough sleep because they’re naturally night owls (like me) and find almost anything before 2 or 3 a.m. more interesting than slumber? Or what share suffer from a recurrent resetting of their biological clocks from exposure to night-time exposure to blue light — including that spooky glow given off by computer screens — so that their bodies no longer recognize when it’s bedtime? Or do today’s teens so drug themselves with caffeine to stay alert while doing homework that when it’s over they can’t immediately nod off?

Insufficient sleep impairs learning, impulse control, and judgment. It appears to even predispose people to disease. Indeed, one motivation for the survey was to probe kids’ behaviors and the extent to which these might help explain four leading causes of death among 10- to 24-year olds: motor-vehicle crashes, other unintentional injuries, homicide and suicide

Even a day’s sleepiness, recent studies have shown, can perturb hormone concentrations in the body in ways that not only foster hunger, but also can encourage the preferential use of calories to produce body fat, not heat and energy. And not surprisingly, 29 percent of the students in this study were overweight, if not obese. Other studies have also observed that kids who sleep less tend to be heavier.

If we want to find ways to encourage healthy habits, we need to understand what the obstacles to them are. And this new study certainly jolts us awake as to the magnitude of our kids’ potentially risky sleep deficits.