That is a good question.

Depending on the aircraft cruise alt cabins can be kept between 5-6k. 5k is a general guideline, hypoxia will affect people in many different ways.

(Opinion) Also night vision unfortunately isn't as stressed in airplanes heading for class A airspace. Many of these cockpits are designed with lots of white light too. Night vision is important but not as import as in a c152 around 1000 feet.