I remember one week of college, that for some reason, my body wouldnt let me get more than 2 hours a night, and generally I was only getting 45-60 minutes per 24 hours.  I would just wake up, and even though I was still really tired, I couldnt get back to sleep.  Possibly it was my body rebelling over my activities of the past weekend, because I was not under any extra stress that I can think of.  Anyways, this started on a Sunday, and continued for the entire week, until I hit Friday.  I got progressively more pissed off at everything.  Walls pissed me off, furniture... you name it.  When Friday classes ended, I got myself a bottle of Jameson, some beer, and was passed out by 8PM.  I woke up at 10AM the next day, and still felt frigging tired.  However, that was the end of my little adventure with insomnia, and what I (and my roommates) learned was... you dont want to be near me when I have gotten very, very sleep deprived.