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Good-night, teen. Too little sleep can harm young brains

Across the country each morning millions of groggy teens are dragging themselves out of bed and trudging sleepily off to school. NBC's Dr. Nancy Snyderman reports on some surprising findings about the toll sleep deprivation has on our kids.
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Across the country each morning, groggy teens are dragging themselves out of bed and trudging sleepily off to school. These bleary-eyed young people are often too tired to take in much of what’s being taught in their early morning classes.

But that’s not the only downside to a nation of chronically tired teens — researchers now worry there may be other, more serious consequences. As part of the NBC Nightly News with Brian Williams series "The Teen Brain: A Work in Progress," Dr. Nancy Snyderman examines the toll sleep deprivation can have on our kids.

Young people are sleeping just seven-and-a-half hours on weeknights, a full two hours less than experts recommend for adolescents, a new poll by the National Sleep Foundation has found. Such sleep deficits may interfere with brain development and increase the chance that a teen will develop attention deficit disorder and other cognitive problems, along with heightened risks for obesity, immune problems and depression, scientists now believe.

“Our 18-year-olds need at least as much sleep as our 10-year-olds,” says Dr. Mary Carskadon, a professor of psychiatry and human behavior at Brown University and director of Chronobiology and Sleep Research at Bradley Hospital. That’s because this is an age when major construction is going on in the brain, Carskadon explains.

New research, including Carskadon’s, has shown that the body uses sleeping hours to hook up critical new circuitry in the developing brain.

“We can see during sleep the emergence of new networks,” she says. “So, we know that sleep has a fundamental role in protecting and growing and strengthening the brain — and strengthening what we’ve learned.”

The theory is that the brain constructs connections to an important brain structure, the frontal lobes, during sleep, says Dr. Jay Giedd, a neuroscientist and chief of the Unit on Brain Imaging in the Child Psychiatry Branch.

“The sleep changes that we’re seeing in ages 16 to 18, I think, reflect this really busy time in the frontal lobe parts of the brain,” Giedd says. “All the things that the frontal lobes of the brain help us do — control impulses, make long term decisions, sort out complicated priorities — get worse with sleep deprivation.”

Sleep is also critical for the brain to assimilate the day’s experiences, experts say.

Tech temptations
Studies have shown that the brain uses sleep to organize the deluge of information that floods in during waking hours. Not every experience needs to be remembered and it’s the brain’s job, when consciousness goes offline, to sift through every bit of information and decide which items are important enough to stash away in long-term memory. Then, like a librarian with a stack full of new books, the brain files memories away for easy access later.

Scientists like Carskadon worry that the fallout associated with poor sleep may go far beyond forgetting what happened in early morning classes.

“When kids seriously limit their sleep, any number of bad consequences can ensue,” she explains. “There’s evidence that things like attention deficit disorder can be caused by insufficient sleep. There’s evidence that some of the overeating and obesity we’re now seeing in young children and adolescents can also be attributed to not getting enough sleep.”

Studies have also linked sleep deficits in teens with a host of other problems, including a lack of motivation, inattention in class, susceptibility to infection, Carskadon says.

What makes it more challenging is teen brains are wired so that they resist early bed times, experts say. And all the tempting technologies that can be found in many teens’ bedrooms — TVs, computers and cell phones — can keep kids too wired to sleep for hours after they turn in.

The solution, experts say, is for parents to set a firm bedtime for their teens and to ban high tech entertainment from the bedroom. That doesn’t guarantee that kids won’t find a way around the rules, of course.

“When I was a teenager, I would be under the covers with my flashlight if I was reading past bedtime,” Carskadon says. “So teenagers are always trying to push the envelope.”