Sleep has hardly changed since neolithic humans tossed and turned in their caves. In the past it was sabre-toothed tigers, now it is social media that keeps us awake. Human sleep as we know it today evolved hundreds of thousands years ago, to suit a hunter–gatherer lifestyle. It’s not always compatible with our modern lives, but remains an essential function, vital for our health, well-being and daytime functioning. In this groundbreaking new book, Dr Merijn van der Laar investigates the origins of sleep based on archaeological findings and anthropological studies in contemporary hunter-gatherers, looking at the major discrepancies between our primordial bodily needs and our current sleep-inhibiting behaviour. Cave dwellers lived in balance with the forces of nature. They had adapted perfectly to environmental influences such as light, temperature and seasonal variations. The way they ate and moved during the day must have had a positive effect on sleep quality. We need to look to their example, and adjust our eating, exercise, light, temperature and, last but not least: our expectations towards sleep. By taking on board the ancient wisdom of our ancestors, we will improve the quality of our sleep, the way our bodies were designed to do it.