I have these "jerks" when I'm sleeping. Like in the dream, I usually trip or something that, and somehow reflects in real life. I can feel it happening, but other people don't seem to notice me jumping like that.
Those are myoclonic jerks. Everyone has them, usually when just falling asleep. Your brain is basically checking up on the rest of your body which causes a jerk. This is where people get those feelings of "landing" as they wake up, or tripping in your case.
Anyways, it seems that you're looking for someone other than yourself to blame for you being unable to learn new material in class. It's completely on you, though. If it goes as far as you being unable to fix your sleep problems, then take responsibility and ask your parents or seek medical help.
I'm not the kind of person to express my problems to people.
You probably should.