I don't understand

I really don't understand... I woke up shortly after 6 this morning, and felt awake. This wouldn't have bothered me, except that never happens, and I didn't get to bed until after midnight. I tried lying in bed for a while to see if my body wanted to go back to bed, but it doesn't seem to want to. (Although now that I've gotten up, I'm starting to feel a bit sleepy again.) So, the question is, if I get up now, will I be tired for the rest of the day?