It is indeed about the sunset and especially the last phases of it. It's also why red light is recommended for night feeding when breastfeeding.
Works for me, both reducing the blue light and worked for my baby, too, using only deep orange and red light of a cheap LED color change lamp. Apparently works for many, since red nursing lights are suddenly sold everywhere.
I thought red light was recommended for nighttime because it doesn’t interfere with natural night vision.
The sunset and also fires. Humans have been making fires for a million years and in addition to allowing us to evolve much smaller guts they've also had time exert pressure on our behavior.