The reason that red lights are used in making and producing pictures from film is that when the process of making the picture is taking place in the darkroom, a vast majority of the pictures are able to stand the color and not show any kind of sensitivity to the color like it would do with other colors. Red light is mainly associated with the making of black and white pictures.
Too much light would mean that the pictures would become overexposed and you would not want to have that happen. The the exact opposite would be the standard when it comes to the producing and making of colored photos. At that time, the darkroom would have to be completely void of any kind of light. When it comes to making black and white photos though a red light would be needed in order for the picture to come up like it should.
Red lights are used for developing films in a darkroom because most films used are sensitive to all colors except for red. When you are developing a film in a bright room or you use a standard light, the film will absorb all the light and will only produce overexposed photos.
Red lights are usually used in developing black and white photos as black and white films are not sensitive to red light. However, if you are going to develop colored films, a completely dimmed room is required. But there are special lights nowadays that you can use in developing colored photos. If you are planning to obtain black and white photos, you can safely use a red light in your room.