Research during the past two decades has produced major advances in understanding sleep within particular species. Simultaneously, molecular advances have made it possible to generate phylogenetic trees, while new analytical methods provide the tools to examine macroevolutionary change on these trees. These methods have recently been applied to questions concerning the evolution of distinctive sleep state characteristics and functions. This book synthesizes recent advances in our understanding of the evolutionary origins of sleep and its adaptive function, and it lays the groundwork for future evolutionary research by assessing sleep patterns in the major animal lineages.

"This book is necessary reading for anyone working in sleep medicine. The reader will understand better why today, despite the abundant research reported in thisbook, we are far from understanding the entire function of sleep in humans. Yet at the same time, a good understanding can be gained about the evolutionary threads that can be perceived through phylogenetic analyses. We can use investigations of many different models to improve our knowledge of both animal and human sleep, and design protocols to pursue our quest to understand one of our vital functions.
Mia Zaharna Christian Guilleminault, Division of Sleep MedicineStanford University for American Journal of Human Biology