[mwattsun]

I spent months underwater on a submarine and we used mostly red lights in the sleeping quarters and the control room. I don't know the theory, but I figured red lights don't produce the momentary blindness of looking at a white light.

[alephxyz]

Red light doesn't overlap as much with the sensitivity of the rod cells in our eyes which are responsible for night vision (see https://commons.m.wikimedia.org/wiki/File:1416_Color_Sensiti...)