Red light is used to preserve night vision

http://wiki.answers.com/Q/What_is_the_purpose_of_the_red_lights_used_in_submarine_control_rooms

What is the purpose of the red lights used in submarine control rooms?

Red light is supposed to be easier for the eyes to transition to darkness. Red lights are also used on the bridge or pilot house of boats and ships. It does allow you to regain your night vision quicker.

http://en.wikipedia.org/wiki/Red

Red light is also used to preserve night vision in low-light or night-time situations, as the rod cells in the human eye aren't sensitive to red. 

http://en.wikipedia.org/wiki/Night_vision

In biological night vision, molecules of rhodopsin in the rods of the eye undergo a change in shape as light is absorbed by them. Rhodopsin is the chemical that allows night-vision, and is extremely sensitive to light. Exposed to a spectrum of light, the pigment immediately bleaches, and it takes about 30 minutes to regenerate fully, but most of the adaptation occurs within the first five or ten minutes in the dark. Rhodopsin in the human rods is less sensitive to the longer red wavelengths of light, so many people use red light to help preserve night vision as it only slowly depletes the eye's rhodopsin stores in the rods and instead is viewed by the cones.