Many millennia, actually. A million years at least, quite likely more. Co-evolving to be comfortable with a certain quality of light, is a good argument for ma

Many millennia, actually. A million years at least, quite likely more. Co-evolving to be comfortable with a certain quality of light, is a good argument for maintaining that quality of light, and for not using light with a quality which triggers subconscious (or conscious) discomfort.