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Replay chat: What makes the teen brain tick?

NBC's Dr. Nancy Snyderman takes a look at the latest science suggesting that multi-tasking may not be that bad for teens after all—unless it's keeping them from getting enough sleep.

According to Dr. Jay Giedd at the National Institute of Mental Health, the teen years are critical years for brain development, and this period of change for our brain has effects into adulthood. Will all this multi-tasking during the teen years make them less able to focus on one thing when they have to? Or do digital distractions make their minds stronger?

And we all know that it’s difficult for teens to wake up. But new research by pioneering sleep researcher Dr. Mary Carskadon looks at what’s happening in the teen brain while they’re asleep. She found that late adolescents have a reshaping brain chemistry during sleep, requiring them to sleep even more than previous research. During these years, key brain connections are happening in the areas of the brain that deal with decision making.

In a live chat moderated by NBC's Dr. Nancy Snyderman, Dr. Giedd and Dr. Carskadon responded to readers' questions about what's really happening inside their teenagers' minds.

See more health reporting from NBC's Nightly News with Brian Williams, MSNBC and msnbc.com.