Who Needs Sleep?

Apparently I do not.  For some reason, my body has decided that three to four hours of sleep a night is sufficient.  I tell you that it is not.  Yes, I tend to go to bed quite late, but once I am in bed I expect to actually go to sleep.  This last week, I have spent many hours awake in my bed.  One should not see that it is 4:30 in the morning as they lie in bed.  Last night I even went to bed utterly exhausted but I couldn't sleep.  I was pretty much delirious, that's how tired I was, you could even ask my roommates, I'm pretty sure that they got a good laugh out of it, but I couldn't sleep.  There was one night that I did get to sleep fairly quickly, I just woke up every hour or so.  I usually sleep like a rock, what is wrong with me?