The dark room is the one in the diagram with no furniture in it. The problem is the window for the that room is not very large and the room is a middle/internal room in the house. I have thought about taking the wall down (marked with red dotted line) and replacing it with crittle doors or putting in French doors for light but that’s not ideal. The blue lines are windows and there’s another room the other side of the ‘dark’ room that we can’t knock through to so there’s no scope to put another window in it.
The two problems are I want the two rooms to remain separate/private from each other as one is used for visiting guests (has a sofa bed in it) and also the sofa in the lounge needs to go against the wall which we could take down (furniture can’t be rearranged as it’s the only way it fits!) It’s already painted white and has a light coloured carpet.
I’m at a complete dead end on what I can do. Has anyone found a way round a similar problem with an internal room?