Studying vs. Sleep the age old question.

I am really really tired. All I want to do is lay down and nap, but its nine o'clock at night so I really would be going to sleep for the night, and I really have to get studying. I have like I think I have stated before 2 exams on Friday and Saturday, my Calc III, accounting followed by Stats I and Marketing. I need to study, but I think I am going to sleep instead.