Hi there, I see you are new here and you asked this question the very first thing - actually, I don't know the history except my own, and that rainbows are very powerful light healers so I think there should be a Rainbow Therapy! It is not an exact practice, nor do I say it is in my article. I sell prisms that make rainbows and believe everyone should experience pure spectral colors as often as possible. I have them in my shower sky light so take rainbow showers - it's awesome! We are all made of energy, of light if you will, so being able to witness the vibration a rainbow of light makes is a very healing, restorative practice.