It is not uncommon for people with guns to peek around doorways into dark rooms. There is a problem with that, of course, because the “peeker” is illuminated by the hallway or room he may be standing in. If you can’t turn the other guy’s room light on, at least turn yours off. If the darkness is equal but there is some ambient light, you will be able to see as well as the criminal and not have to give yourself away with a flashlight. Always use the tools under your control.