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Using pure red light for the night is a good idea, since it doesn't decrease our eye's ability to see in darkness. That's why it is used in submarines too (if the electricity is cut, night vision of the eye is already fully functional).

A bit more detail: the rods in our eyes responsible for night vision need ~45 mins of darkness for full adaptation (though some night vision is achieved after a few minutes already). Light disrupts this adaptation - but not red light! So with only red light on, both the night-vision rods and the red-sensitive cones are active the same time.

Source: https://en.wikipedia.org/wiki/Night_vision#Biological_night_...