I found the same with both O. mercatoris and the macropus I’ve had. The O. briareus have all seemed to be happy to become more crepuscular and less nocturnal when living in a busy upstairs tank.I have wondered about light slightly differently. How much and how total is their dark time? I noticed with O. mercatoris, it seemed that never giving them full darkness (always with a place to hide and red lights on at night but not ever all lights off) seemed to help with training a reasonable and observation time. It appeared that if all lights were off during part of the night, that is the time the animals would come to hunt.
Are there any windows in your basement, or is all the lighting artificial? If artificial, do you have a regular “photoperiod” for the lights outside of the tank?What I find strange about my friend Maurice is that he seems to stay about 20 hours in his rocks, caves and housing and then in the early morning he may be out for a few hours. I recently saw him outside once in the afternoon but the very most of the time he is not to be seen. Kind of strange, isn't it?
Can you set up a light on a timer in your basement, not too far from the tank- so you can simulate daytime? That might help a crepuscular animal (you have an aculeatus, right?) want to spend more time out of his den...There is a big celler window but that's 6 meters away. There is not extremely much light shining into. If I wanted to read in the room I had to switch on the light even at daytime. The lights are usually shut down.