Night time is more complicated still because you have to give a much more direct sense of where these lights are coming from. Since light sources are limited during the night it would not make sense to have stray lights dotting around. Instead you will have to show some light sources, such as light coming through a window into a dark room. You have to provide a second layer of logic in situations such as these and decide if you want it to be moonlight, a streetlight, or another source. Each of these decisions will affect the color temperature you will go for, the exact position of the light, whether or not you will place an object in front of the light source, or whether or not you will be applying gels. When outdoors at night you have to do the same thing, but you may get away with sourcing large lights from blanket areas of the city where ambient and bright lights persist even at night.