Question of the Day

I go to bed at the same time every single night. So, why is it that I have to force myself to wake up at 7:30am every weekday morning so that I can go to class, but then when I want to sleep in Saturdays, my eyes automatically pop open at 7am? I don't get it. Is my brain telling me that it would rather watch Saturday morning cartoons rather than go watch videos about constitutional law?