I actually had this problem one year in college. For two weeks solid I wouldn't fall asleep until midafternoon and I'd be up for the next 18 or so hours. It sucked! I tried alcohol (heavy dark stout ales can fill you up enough to get you groggy if you can handle the taste), and I tried all sorts of "get me to sleep" ideas. None worked. What I ended up having to do was actually just the opposite.

Try keeping yourself awake for a full 14+ hour period. Get active and social - it helps to keep you from sitting around and inadvertantly falling asleep). After more than 24 hours pass, go to bed at an appropriate bed time. Now here's the part that's important -- set analarm to wake you up at a decent morning hour, like between 830 and 10 in the morning. Th
en go out and be active for the day so you come home exhausted by the time you go to sleep (SAME TIME AS THE NIGHT BEFORE). Wake up at the same time in the morning. Lather, rinse, and repeat the wake/sleep process for at least one more day and see if that forces your sleeping patterns back to normal.

Good luck! I know I hated feeling off like that!