"No, we don't have the lights on because it's dark. We have them on because the power company needs the money."Ever notice that in TV land, people rarely use a light switch? It doesn't matter which room of a house the character(s) currently occupy; when they move to another room, the lights are already on. And when they leave a room, the lights stay on. Sometimes, characters will even arrive home after a night out, and the lights in the house are already on. The only time the lights go out is when everyone goes to bed, or when darkness is essential to the scene (for instance, an allegedly amusing "fumbling about in the dark" sequence, or to facilitate The Reveal). Or, if a character does turn out the lights upon leaving a room, it's usually symbolic. Most common in Sit Coms and Soap Operas, where it can be externally justified by the fact that, since such shows often employ Three Wall Sets depicting an "open" architecture, they utilize shared lighting rigs. Further, as anyone who has ever used a klieg light can tell you, big studio lights don't flick on and off in the same manner as 60-watt bulbs; they require long periods of warm-up and cool-down, and turning them on and off during a shoot could be distracting. Furthermore, these sets will typically feature numerous practical lights (table/floor lamps, sconces, etc). No matter how many such lamps are present, every last one will be burning, day or night. This could be seen as perhaps an attempt to justify the amount of illumination the studio lights are pumping out. One of the few times this trope gets a mention is the Christmas Episode, where there are so many more lights than usual that someone will feel the need to, er... hang a lampshade. Of course, if they ever do switch off the lights, it's not like it gets dark anyway. See also Law of Conservation of Detail .
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