Evolutionary aspects of sleep and its REM and NREM states

Abstract

Publisher Summary This chapter discusses the evolutionary aspects of sleep and its rapid-eye-movement (REM) and non-rapid-eye-movement (NREM) states. The neural adaptation of circuit multifunctionality confer great efficiency of brain function at early stages of evolution, in animals that lead relatively simple lives with few needs for long-term memories, such as many “lower” invertebrates. As more complex lifestyles and detailed focal vision evolved, needs for self-initiated and reflexive activities increased, and recognition of many locales, conspecifics, and other forms of life became essential. These developments are accompanied by greatly expanded needs for neural processing supporting sensory and motor activities, and establishing and storing long-term memories. Because these categories of neural processing occur largely in shared regions, brain functioning would have become increasingly maladaptive had the evolution of these more complex lifestyles not been accompanied by the evolution of compensating adaptations. In this treatment, the utility of an evolutionary approach has been illustrated—always seeking and mindful of differential adaptedness and underlying selective pressures—to guide research into the origin and functions of sleep and its REM and NREM states.