Isn't 4000k far more "natural"? A full moon is 4000k.
The night time lighting humans(and our non-human co-inhabitants of earth) have evolved with and known for a very longtime comes from fires of various types, flames with a much warmer color temperature.
Also, intensity is orthogonal to color temperature.
Consider the spread of lactose tolerance, a recent (no more than 10,000 years and perhaps less) mutation which has spread to 35% of humanity in that time. We have had plenty of time to co-evolve with fire, and doubtless, we have done so.
Its probably to do with cooked food, not vision - which is already co-evolved with the Sun, for when we are active/hunting/etc.
Wild animals very much do not. It's likely that our mucus membranes have also adjusted to the presence of more smoke: this doesn't prevent cancer, which is a post-reproductive problem for the most part, but it does keep smoke inhalation from being immediately debilitating.
Does it mean that fire doesn't fool our circadian rhythm into thinking it's still daytime? Sure, why wouldn't it? We've had a very long time to adjust, and getting appropriate amounts of sleep increases fitness in an obvious way.
We haven't had more than a hundred years of adjusting to bright blue-wavelength light after dark, however. So it could affect our circadian rhythm, and as studies show, it does.