I have noticed that when all the lights are on, people tend to talk about what they are doing - their outer lives. Sitting round in the candlelight or firelight, people start to talk about how they are feeling - their inner lives.
They speak subjectively, they argue less, there are longer pauses.
To sit alone without any electric light is curiously creative. I have my best ideas at dawn or nightfall, but not if I switch on the lights - then I start thinking about projects, deadlines, demands and the shadows and shapes of the house becomes objects, not suggestions, things that need to be done, not a background to the thought.