I read Dr. Ott's books back in the 80's and spoke with him by phone once or twice before he died. This extremely important 1974 documentary on the health effects of full spectrum light and often feared the ultra violet frequencies has been almost lost to humanity as few have ever seen it. He told me that he wished he had a way to have everyone learn this important information. So now, 40+ years later with the internet that he never really had, I am fulfilling his request to make it available to everyone. The quality of movie film recording was not great back then but it is pretty good considering when it was shot. Watch and learn. I have been recommending, selling and installing full spectrum lighting for many decades.