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 and well-being. Dr Merijn van de 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 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.