Well I know many people do keep theirs in pitch black, and my does too. I still see my ball moving around the moment the lights come on though. It could be possible that there still is some light I cant pick up, but in your case lets say it really IS pitch black. Snakes still sense their environment in other ways, including through their version of thermal imaging, or so I think. And these are really sensitive, so I believe they still more or less can see what theyre doing.