Book excerpt: The introduction of artificial lighting extends the time of wakefulness after dark and enables work at night, thus disturbing the human circadian rhythm. The understanding of the physiological mechanisms of visual and non-visual systems may be important for the development and use of proper light infrastructure and light interventions for different workplace settings, especially for shift work conditions. Visual and Non-Visual Effects of Light: Working Environment and Well-Being presents the impact of lighting in the working environment on human health, well-being and visual performance. The physiological explanation of the visual and non-visual effects of light on humans which discusses the biological bases of image and non-image forming vision at the cellular level may be of particular interest to any professional in the field of medicine, physiology, and biology. It is one of the intentions of this book to put forward some recommendations and examples of lighting design which take into account both the visual and non-visual effects of light on humans. These may be of particular interest to any professional in the field of lighting, occupational safety and health, and interior design. "What effects on health can a light ‘overdose’ or light deficiency have? What is bad light? The authors of the monograph provide answers to these questions. Just as for a physicist, the dual nature of light comprises an electromagnetic wave and a photon, the duality of light for a physician comprises visual and non-visual effects." --------------------------------------------------------Prof Jacek Przybylski, Medical University of Warsaw "This is a unique publication in the field of lighting technology. The authors have skillfully combined both the technical and biomedical aspects involved, which is unprecedented in the literature available. As a result, an important study has been created for many professional groups, with a significant impact on the assessment of risks associated with LED sources." --------------------------------------------Prof Andrzej Zając, Military University of Technology, Warsaw