We may have to just agree to disagree on this one. I see what your saying about some rack systems. Some do not have clear tubs but do have viewing window, for instance the freedom tubs. I am not familiar with the systems that do not have clear tubs so I can't speak on that subject. But I will say that the day light changes with the seasons just as the temps do. The day light may not be as important in ball pythons seasonal changes as the temps are .... But I believe day light effects ALL natures creatures. With the ball python I believe that it allows them to know when to come out and roam and when to hide and rest, therefore effecting their activity. On a much more in depth level I believe it to effect their behavior, activity and quality of live (health).