This is the Second Edition of a book that has been very popular since its introduction in 2008. Since then there have been many studies that confirm that using ordinary light at night is damaging to sleep and increases the risk of deadly illnesses like diabetes, obesity, heart disease, and breast, colon and prostate cancer. The author introduces the dawning of a new epoch in lighting, "Lighting for Health." But this book is also a very personal book. It describes how the medical profession is slow to embrace new ideas without years of clinical testing but how simple changes in your life style (changing to light bulbs that don't make the blue light that suppresses melatonin) can greatly improve the quality of your sleep and may reduce your risk of serious illness. It documents the dangers associated with the use of sleeping pills and reviews in detail the evidence that maximizing natural melatonin has many health benefits. It summarizes the results of many recent studies concerning how melatonin fights cancer in so many different ways including reduction in the risk of metastasis in cancer survivors. The author provides suggestions to shift workers for ways they can preserve their circadian rhythm and their supply of melatonin while working different shifts. You will learn that we are beginning to have some completion in providing low blue light products including a project funded by the Department of Health and Human Services to develop a safe light source, i.e., one that does not suppress melatonin.