There is a standard of how comfortable or pleasant light is to human eyes. We call it CRI – The Color Rendering Index. The authority that determines this quantitative measure is The International Commission on Illumination (CIE) and it deals with issues of light, illumination, color and color spaces.
In simple terms, what CRI determines is: how natural do colors of objects look under different kinds of lighting. Natural in this case means, as they would appear under light that appears color free (such as sunlight or some types of incadescent light) and thus possible for the human spectator to identify all shades of color of the given object.
