Hello!
Fright Level: There is nothing controversial about the operation of the rods and cones in one's eyes is well documented and fact. Once night vision is established, it's vital to keep it, hence the need for a red illumination.
That's what I was tought, too. But through my amateur astronomy hobby, I was confronted with other opinions, like the one expressed here:
Night Vision - The Red Myth. Honestly, I don't know what to believe... The (quite modern) aeroplanes (C560) that I'm mostly flying do not have red lighting, but dimmable white lights as this article suggests.
Greetings, Max