Why am I always tired? Why can't I sleep at night? Why do I suffer from jetlag? We all have a body clock; a biological structure that controls how we feel, our mental and physical performance, and whether we are active or asleep. Sometimes it can go wrong, producing some forms of insomnia and even depression. This book explains how the body clock works, how and why it can work against us, and the measures we can take to optimise our feeling of health and wellbeing. An essential book for anyone who wants to better understand their body.