I've had a theory that different color can affect people due the the way colors are created from lightwaves.
The basic concept is that regular white light is made up of all light waves in the spectrum but they can be split by a prisim into all the different colors of light. When we see a red apple or yellow tennis ball what's actually happening is that the white light is hitting the object and it is absorbing that light except for a narrow spectrum which bounces off. So the apple is absorbing all spectrums of light except for red while the tennis ball is absorbing all but the yellow spectrum. If something absorbs all the spectrums it looks black.
We know that some people are sensitive to different spectrums of light. For example they might get a headache or feel nausea when exposed to UV light or florescent light. These types of non natural light produce an incomplete spectrum compared to sunlight. Whi h makes me wonder if the incomplete spectrum coming from certain colors can affect people in the same way.