Pacman frogs are pretty tough. I regularly have nights in the mid 60s and mine still eats like a pig. "hibernating" usually happens when the tank dries out so the frog will burrow and create a mucous cocoon to conserve water. but since the frog is splayed out its legs, im not too sure. if you answer the questions Lija provided, we will be able to get an answer. keep us posted!