How did I do that?

I woke up pretty early this morning and since I was awake, I decided to go ahead and start getting ready for school. Which worked out well, because I got dressed and ate a decent breakfast, but at the end of all of that, I was still very tired. I figured that it wouldn't be a big deal if I took a twenty minute nap because normally, if I take a nap like that, I'll be pretty invigorated. Well, that did not happen today! My twenty minute nap turned into a TWO hour nap making me late for school!! It turned out alright in the end because we were just watching a documentary in that class today, but I wasn't really happy with myself. I never like to be late, who does, and I am usually early if anything. I guess that I must have been really tired... at least when I got up, I stayed up!

Does that ever happen to any of you?