Abstract: The invention is directed to improved methods of optimizing light for therapeutic or well-being effects. The invention also provides materials, methods, computer programs and systems for the creation and use of optimized Sight filters and illuminants. The methods of the present invention also include the use of optimized light filters and illuminants for use in treating diseases sensitive to modulation of intrinsically photosensitive retinal ganglion cells. The usefulness of the present method is that it results in the treatment of diseases and/or conditions related to light.