We suggest that you go through your text and highlight all the words that have to do with darkness. Words like "black" (there are eleven), "gray," "shadow," or "dark." Then go back and look for words that have to do with light. You’ll find "lusterless" (once in the first paragraph and once in the last – interesting, no?), "gleam," "brightness," "flame," "shimmering," and about two dozen more. (And keep a special look-out for anything "white.") In a short story of 39 paragraphs, this is not an accident.
The imagery of light and darkness sets a great mood for "The Return of Chorb." The blackness of night puts us in scary-movie-mode, and the unearthly appearance of bright lights of course makes us think of ghosts (or UFO’s, but we’re not in a Bradbury tale here). Because of the way Chorb’s wife died, we should already be thinking about whiteness and lights by the time Chorb gets to the creepy hotel room. Check this out: "Her death appeared to him as a most rare, almost unheard-of occurrence […], caused by the impact of an electric stream, the same stream which, when poured into glass receptacles, yields the purest and brightest light." Need we say more?