Streetlamps, neon signs – an ever-present glow that has changed the natural world and adversely affected our health; Paul Bogard illuminates the problems caused by a lack of darkness. We live awash in artificial light. But night's natural darkness has always been invaluable for our spiritual health and the health of the natural world, and every living creature suffers from its loss. Paul Bogard investigates what we mean when we talk about darkness. He travels between the intensely lit cities – from glittering Las Vegas to the gas-lit streets of Westminster – and the sites where real darkness still remains, such as the Brecon Beacons and the island of Sark. Encountering scientists, physicians, activists and writers, Bogard discusses how light is negatively affecting the natural world; how our well-being is significantly influenced by darkness or its lack; and how it's not a matter of using light at night or not, but rather when and where, how and how much. A beautiful invocation of our constant companion, the night, which returns every day of our lives, this book reminds us of the power and mystery of the dark.