Oddly, our teenager did the "sleep in" thing for about six months, now he bounces out of bed at 6:45 most mornings and 6:00 when he is going to rugby training!
My school offered a few tracks. The earliest track had you out of school earlier, but classes started at 7AM. Everyone took that track at my school because people could get out earlier and do things when it's still light outside. I regularly woke up at 5:30AM with no trouble. It's not really uncommon for teenagers to wake up at 6AM. For some weird reason that changes in college, and everyone gets lazy and sleeps in. (despite college usually offering superior choice of schedule)