If you divide the solar spectrum roughly into half, you will have: the reds,
oranges, and yellows on one side and the purples, blues, and greens on the
other. The former being roughly the warm and the latter the cool colours.
Warm colours are stimulating. The reds, oranges, yellows and all the off whites
that tend to this direction possess all the qualities of warmth in that they are
hot, stimulating and soothing to our EMOTIONS, which crave warmth.