Can't Sleep!!!

I seem to have this problem when it's really late on a school night. I just can't seem to fall asleep tonight for some odd reason. I don't know what it is. Usually on a school night when it's late before I go to bed my mind seems to go on overdrive. I seem to think about a ton of things like right before I go to bed. It is weird how I do most of my thinking out of an entire day when I'm laying in bed minutes before I fall asleep. I think if I could do all of my school assignments like really late at night I think I would make all A's. That goes to show how much time I spend late at night thinking. Nothing else. Just thinking. It drives me crazy! I need sleep. My over active mind needs to chill. I'm losing sleep so much all because my mind seems to be running on a treadmill. That's how much it over activates. I need MORE SLEEP, MUCH MORE SLEEP!!! But I can't seem to FALL ASLEEP!!! Why? Why does this happen to me?