Dead Tired

Again. I did 7 and a half hours of studying today, most of it productive, but I can't seem to work my way up to a full 8h. On the one hand, I'm mentally exhausted, on the other, my mind craves stimuli that don't involve cells and names of long-dead doctors. When the high point in your day is a T-lymphocyte expressing CD69 on its cellular membrane, you know your life sucks.