Light is changing, dramatically. Our world is getting brighter – you can see it from space. But is brighter always better? Artificial light is voracious and spreading. Vanquishing precious darkness across the planet, when we are supposed to be using less energy. The quality of light has altered as well. Technology and legislation have crushed warm incandescent lighting in favour of harsher, often glaring alternatives. Light is fundamental – it really matters. It interacts with life in profound yet subtle ways: it tells plants which way to grow, birds where to fly and coral when to spawn. It tells each and every one of us when to sleep, wake, eat. We mess with the eternal rhythm of dawn-day-dusk-night at our peril. But mess with it we have, and we still don't truly understand the consequences. In Incandescent, journalist Anna Levin reveals her own fraught relationship with changes in lighting, and she explores its real impact on nature, our built environment, health and psychological well-being. We need to talk about light, urgently. And ask the critical question: just how bright is our future?