I cant sleep at night?

[ARIEL]

I am a male at 16 and Ive been only getting 4 hours of sleep for the past 3 nights. ive been trying to sleep earlier because of school but its just really hard to fall asleep. I think it has to do with the whole sleep cycle thing cause during the summer i would go to bed at 3 in the morning and get up at 12 in the afternoon now since school is here i have to go to bed at 11:30 and get up at 7:50 how long will it take for my body to change its cycle !

[Ivers]

Hi Ariel,
Manage stress with regular and early workouts and be modest about food and drinks. Don’t over indulge, quit alcohol, smoking and caffeine. Create a restful sleeping schedule and environment and try to relax before going to bed.

What if you get critical illnes?

[Rinek]

That can be because sometimes we go over the top which makes the body a bit uncomfortable and that can be the reason behind what you have mentioned.
I advice you to moderate your workout routine and other activities you do that will surely help you.