Comment by pwg

> This is why our streetlights used to be orange, until the LED companies stole the old light companies’ business without realizing there was a reason behind outdoor lights’ usual spectrum.

Ah... No... The yellow streetlights were not yellow because the particular color was a choice, or because "yellow" was better for humans in some way. They were yellow simply because those were sodium vapor lamps and the sodium emissions spectrum is in the yellow range. And they were sodium vapor lamps because sodium vapor lamps were more energy efficient that mercury vapor lamps (the whiter looking street lamps as compared to the yellow sodium ones).

And both mercury vapor and sodium vapor were used because they were the high energy efficiency offerings for street lighting before LED's came along and offered even greater energy efficiency.

And when you count out how many street lights exist, even small amounts of energy efficiency improvements per lamp multiply quickly into large cost savings in paying for the energy usage (street lamps are not free, someone, typically the local government, is paying for the energy consumption).