Hypersomnia. That i have to take.

Hello Doctor Usually I used to fall asleep anytime and in any condition. 2 year back when I was in my last high school and in order to pass my last exam I used to slept very late and I accumulated drowsiness, after that it's was very difficult for me to wake up each morning. I began to sleep usually in classroom and It's was difficult for me to be 100% active at school. Now I'm at university and the problem is becoming more than 2 year back, I sleep usually early and wake up each morning very tired, In the Bus I used to sleep, at school I used to sleep I can't take the control of myself, impossible for me to get concentrate in classroom because I usually feeling tired and getting sleep. I have so many drowsiness that I can't study, I always sleep on my books. Please Doctor tell me what I have to do in order to resolve this problem and if there any medicine that I have to take . Regards