Yeah - we doubt the veracity of what she was told at a cave tour as a child --my opinion is that her tour leader was out terrify en masse -- however, I totally believe that Bobby Hobbes would believe and obsess about that. Just because it is unlikely, does not mean our fanfic pretend heroes won't believe it. Bobby Hobbes also took that exact same cave tour as Snoo and now he is freaking out in absolute darkness.

Anyway - the dark of a cave is absolute - unlike the dark of a coma. I doubt an adult can be affected, but kittens kept in darkness at critical rod/cone development are blind. Maybe that is where he got confused?