Book excerpt: Sleep and Aging provides a unique and timely collection of review articles that cover the gamut of basic and clinical aspects of sleep and the abnormalities in sleep associated with aging and neurological disorders that occur during aging. From the evolutionary basis of sleep and its normal functions in processes such as learning and memory, to considerations of the roles of sleep abnormalities in neurological disorders such as depression, Alzheimer's and Parkinson's diseases, the chapters are written by experts in the field. Several chapters focus on signalling pathways involved in sleep regulation and abnormalities in sleep, including those activated by serotonin and BDNF. Basic and clinical research on insomnia, sleep apnea and other disorders of sleep, are covered thus providing students and scientists at all levels with a valuable source of information to advance their understanding of this important topic in aging, biology and medicine. The circuits in the brain involved in sleep regulation, their neurochemistry, how they are altered in disorders of sleep and current clinical treatments of various sleep disorders are reviewed. The important role of sleep disturbances in neurodegenerative disorders is described and research in this particular area is leading to a better understanding of the relationships between synaptic plasticity, neuronal degeneration and the clinical manifestations of disorders such as Alzheimer's disease, Parkinson's disease and depression. This book is a must for scientists, as well as non-scientists, who are interested in the neurobiology of aging, sleep and neurodegenerative disorders.