i think this book should be required reading for heads of any kind of institution. and an excellent read for everyone else. really good info. it was surprising to me how different types of light affected so many different things. amazing. if a person really cares about their own health and that of their loved ones, two legged, four legged, feathered or plants, read this book. i plan to reread it very soon. i have told several people about it and got a "ho hum, boring, not interested" type response. i am going to locate the lights, try it out for myself. they are not available at the local big box or little mom and pop stores.