I'm a reasonbly bright student, and I have set my sights high for the future. How do I make sure I study?

[pn243]

I know I can do it if I study hard enough.....I proved it to myself last year in my 10th grade board exams, for which i studied hard and got the results I expected. I'm now in my eleventh grade.....everything seems to have gone sour; especially physics. I make study plans every single day yet every single day, I go to sleep without even completing 50% of the planned work. I don't know what's happening to me. It's not like my grades have plummeted or anything; I'm still a topper in class, but i know I ought to study much more intensely to reach the goal I have set for myself, with all this competition.

I somehow manage to while away my time. Sleep seems to be my deadliest foe; I am unable to wake up early and unable to sleep late. I even sleep while studying sometimes.
Though i must do several problems to gain aptitude in physics and chemistry, i get too carried away reading theory. As for biology which used to be my passion, I have completely lost interest in it.

I have no distractions; i am an avid reader, and i sometimes take photographs of plants and animals around me. I have deactivated my facebook account, but i feel i must bring down my usage of email as well. my social life isn't soooo vibrant, just the way it should be.

My real problem is myself, i suppose. I am never able to control myself, assert myself to do what i want to do. Singing helps vent these frustrations, but i am getting more and more frustrated, more and more often.

Worst of all, the entrance exams are hardly 10 months away. I've not even started my preparations.

Can someone please help?