That's not how it works...
My suggestion is to take a suitable painkiller and just go to bed. Use the half awake state to let your mind wander.
It may be inefficient, but it's not counter-productive unlike some people's ideas...
@MoonCat: My schedule enabled me to go to bed and do homework in the morning before school... But from what I gather, yours does not. Which is a shame. Early morning sunrise is the best to write essays by.