The chapters in this book reflect leading edge ideas, reflections and observations. Even though the modern era of sleep research evolved from Aserinksky’s observations of rapid eye movements in the sleep of babies, most work is nonetheless done in adults. There is much less formal work done in youngsters and virtually none in utero and pregnancy itself is virtually unexplored. So, Dr Miller et al’s chapter reviewing sleep in pregnancy is particularly welcome as it incorporates current thinking in how disordered sleep impacts other adult pathological processes. Dr Tomoda and Dr Yamakazi’s datadriven chapter on adolescents with sleep disturbance focuses on metabolic and endocrine data which sheds light.