According to Science Daily, "Teenagers' morning drowsiness is often caused by out-of-tune body clocks, in a condition known as "delayed sleep phase syndrome." Scientists now say that timing exposure to blue light -- avoiding it during the first two hours of being wake, then getting a good dose of it -- can help restore the sleep cycle, so teens feel sleepy earlier at night and are more awake in the morning.
TROY, N.Y.--Teenagers are notorious for staying up late, hitting the snooze button and always running late. Now, however, new research shows they can adjust to a schedule simply by sitting in front of a light". For more see: Waking up Teens
Scientists Show Blue Light Can Help Reset Sleep Cycle