take a 30 minute break, open the window, get fresh air in, watch tv or listen to music, then wash your face and start studying. take 10-15 min. breaks every 1.5-2 hours
Go work out. Take a break and come back to it. If you want it bad enough, you will focus and do it; sans drugs ffs!
shut off the world, and meditate for twenty-minutes.....hit it refreshed and enlightened...
Need focus? Spend sometime with (or call them) those less fortunate than you (like drunk neighbors, silly relatives or gang bangers). That should help.
get new P- ost H -ole D -igger