Natural light surrounds us. Yet not getting enough of the right forms of natural light causes disease. Using decades of clinical research, this text reveals the history of natural light therapy and the newest evidence showing that light therapy heals naturally. This text discusses the basics of light radiation, light waves, sun- and moonlight, and how to produce the best form of vitamin D. The science of using light boxes, infrared therapy, saunas, UV light lamps and sunlight therapy for insomnia, chronic fatigue, depression, cardiovascular issues, dementia and many other conditions is examined, with practical strategies to enhance our moods and help us thrive physically and mentally.