This is what I do:

At school nothing is taught so I study for IIT in the school. I don't pay attention to the teachers. My schoolteachers are too busy trying to complete the syllabus to notice that I am not listening to them .

Don't try any sleeping pills or coffee. Your body needs rest. I would recommend at least 7 hrs of sleep (I sleep a minimum of 7hrs each day and upto 9hrs  on Holidays) . Where there is a will there is always a way. Just remember that 2 hrs of concentrated study is better than 4 hrs of a forced study. You should create an Interest in studies that u enjoy urself while studying (It seems strange)