I love refracted sunlight and spend a good amount of time staring at primary colors refracted from prisms and holographic film. I commonly experience a state change, as if otherwise dormant neural pathways get activated. I play around with Neopixels for this reason and modified my garage door so that my neighbors can get some color in their eyes, too. I believe our indoor, urban lifestyles starve our retinas of the full spectrum of visible light they evolved to process, robbing us of the opportunity to develop our full neurological potential. I would not be surprised if there is a treatment opportunity for OCD/ADD using primary color, as I experience improved self-regulation doing this. It is really unfortunate that UV is dangerous, as such a large portion of sunlight is in the near infrared (50%). Our organism evolved to function bathed in these frequencies, and I think it is likely that many of the pathologies we suffer result from our cells functioning sub-optimally from the chronic lack of this energy input. Living in San Francisco, I feel that I am far enough north to sit in the sun without risk and do so whenever the fog clears. I would note that absorption at shorter wavelengths is very shallow (<1mm), and I guess that the therapeutic effect of Cyan light would be through the retina.