It really isn't important for BP's. Some reptiles truly require a day/night cycle to thrive... but since BP's in the wild spend most of the day hiding in termite mounds or rodent burrows and come out at night to hunt light/dark cycles are more or less irrelevant. BP's aren't huge fans of bright white light. I think most people would say that it is better to keep a BP in a dark cage vs a cage that is too bright.