Isn't there a theory that blue light helps the eyes adjust to night
vision
or something similar?
Your iris doesn't really react to red light. That's why it is used
for night-sight-safe lighting such as in military situations, your
irises will stay open so that your eyes don't need to readapt to
the dark after looking at something illuminated.
Red darkroom safelights are used because the red light is low-energy
light, and film (silver) doesn't tend to react to it. Not sure if
the same (or similar) mechanisms are at work there or not.
-- Jim
