Ambiance is important to followers of the macabre.
Regulating the comfort of our haunted homes, dungeons, and sinister laboratories (pretentiously read “la-BOR-a-tor-eez”) is imperative to making our “guests” feel as unwelcome as possible. Of course, no creepy castle is complete without abundant spider webs and hidden trap doors that open up into our crocodile-infested moats. But more than that, monsters depend on the right kind of lighting to create the right kind of mood.
Especially if that mood is “terrified.”