If a goy shuts off the light in a room on Shabbos I can sleep in it because its not call being nehene from the melocho, since a lack of light is not a considered hanahah. Does this also apply to a mumar who shut off the lights, meaning can I now sleep in that room or is there a knas when it comes to a mumar.
If possible please include sources.
If a mumar shuts off the light other people may sleep in the room, like you mentioned, because he isn’t benefiting from the melacha. The knas regarding other people benefiting from the action when a Jew does melacha is less than when a goy does it. This is because we are not afraid that a Jew will tell another Jew to do melacha. Therefore here it is certainly permitted.
I looked around to see if anyone specifically addresses your question, but the only thing I found was a more stringent case in “Aliba D’hilchasa” vol 61 pg. 172, a question was asked to Horav C. Kanievsky Shlit”a, if someone turned off the lights if he may sleep there, and he answers that although it is preferred that he not sleep there it is halachically permitted.