Wait, are red lights a myth?

[kapuhy]

So, I was doing some googling on lighting inside U-Boats after recent somewhat heated discussions here about various U-Boat interior mods, and found something that really surprised me:

https://uboat.net/forums/read.php?3,...5810#msg-95810

A design study of the Type IXC uboat based on U505, dated 1946 and conducted by the U.S. Portsmouth Naval Shipyard, notes in chapter S64…

"In addition to the above the indicating face plates of practically all I.C. equipment, important gauges, meters, etc., particularly in the Control Room are treated with phosphorescent material so that they may easily be read in the event of a complete casualty to the lighting power supply. The number of units so treated in the Control Room provides enough illumination to allow personnel to move about freely.
Additional fixtures for low level illumination, either blue or red, are not provided for dark adaptation of the ship’s personnel. Use is made, however, of tightfitting red lens goggles."

Having no access to original study I can't verify this of course, and anyway it might just be the way it was done on Type IX's or even just this particular boat, but if true, this would mean that there was actually no red lighting inside U-Boat that we are so used to in all games and movies?