Stepping back from the world has always been part of human life. We're social animals but sometimes we want to be alone. That impulse is as old as civilisation but has never been more urgent. Today, mindfulness and meditation are everywhere and wellness tourism is booming. Whether it's a yoga break, an app or something more like boot camp, retreat is a feature of our lives now. Nat Segnit's book journeys into this human obsession, mining neuroscience, psychology and history to reveal why we seek solitude, what we get out of it, what is going on in our brains and in our bodies when we achieve it.