Bora Zivkovic finds evidence that hormones force teenagers to stay up late:
No amount of bribing or threatening can make an adolescent fall asleep early. Don’t blame video games or TV. Even if you take all of these away (and you should that late at night, and replace them with books) and switch off the lights, the poor teen will toss and turn and not fall asleep until midnight or later, thus getting only about 4-6 hours of sleep until it is time to get up and go to school again.
He argues that teenagers should be going to school later in the morning:
If [teenagers] are driving themselves to school at 6 or 7am, when their circadian clocks think is it 3 or 4am, it is as if they are driving drunk.