procastrinating and cramming....?

why do i feel so lazy today...? my brain is telling me to work my butt off for tomorrow's physio unit exam while my body is telling to relax! is this one mechanism of my body telling to chill in order to remain sane for the rest of the semester?.. last week i work my butt off and i hardly get any sleep. this morning i think i catching a flu and was little light headed. I guess I'm now use to the trill of having to make up in the middle of the night to study? I'm suppose to feel lucky that i wouldn't be cramming but no matter what i do I can't seem to open my book and start reading.. I feel like i know everything there is to know and at the same time i fell like there's so much still i do not know.. how do one master topics in a particular subject? they say repetition is the key.. honestly truth be told, I do not know what I'm doing.. I don't know if my study habits are working.. Unfortunately my study habit in college doesn't work in medicine. They say I'm still adapting.. well I better adapt fast!.. need to wake up early hopefully then my brain will reach threshold and fire an action potential.. right now still in local potential.. haha its physiology!