Most likely your deficit is waaaay too steep. You should not be starving to the extent that you have hunger pains, or are unable to sleep, or your reproductive system or your immune system shuts down :)

Hungry ape gets woken up early because he needs to go and invest his remaining calories from body fat in to digging up a tuber, or trapping a squirrel or whatever...

Edit. Because obviously the ones with the hunger -> no sleep behavioural repertoire survived to pass on their genes.