Strangely enough, I removed the night light from the back of the tank last night and at 6:00 AM (late night side - still) she was out on the front glass. After eating her crab she chose a FRONT den and started digging in so I am more confident with the thought that she is making underground daytime places. What is interesting is that she chose to make a den on the most lighted side. Time will tell if this is just her acclimating to the tank or if lighting has some impact but it is the first time she did not go to the back of the tank at bed time. I am getting the impression that this species may be very near sighted.