Again, it probably is that he's a night person. I understand that on school nights he can't stay up till 1-3, but perhaps a later "bedtime" would help - and no bedtime on the weekends, if that's possible. As contradictory as it seemed, I would get MORE sleep if my bedtime was later rather than earlier, because I had more time to wear myself out and get all that excess energy out into something else - if I was forced to go to sleep at 9, I could easily lie in bed till 2 (ick!), but if I was allowed to go to bed at 11, I could fall asleep by midnight or 12:15. All my energy went into reading or drawing or playing on the computer rather than sinking slowly into madness in my bed. My parents never quite understood that, though, that if I wasn't tired, it could easily take 3, 4 or 5 hours to fall asleep, because my brain would be racing and producing very unpleasant thoughts. So yeah, probably just by virtue of being a night person, high school is not going to be easy getting up for, but earlier bedtimes will NOT help his sleep situation if he has the same sort of late-night thinking that I do when I'm bored and can't sleep!
If I REALLY need to get up the next day, or if I'm just tired of my brain keeping me up, I'll take Melatonin. Nothing stronger, though. I've been on enough prescription drugs, and Ambien messed me up quite a lot the one time I did try it. And to think that I laughed when the doctor told me that a side effect was drowsiness!