Sleep: Circuits and Functions PDF

Preface

Sleep is operationally defined as a specific behavior during which the organism adopts a recognizable posture (usually characterized by the relaxation of the antigravity musculature), the responsiveness to external stimuli is decreased, and which is regulated by a homeostatic process whereby the deprivation of sleep subsequently leads to a sleep rebound . Although the homeostatic process maintains the duration and intensity of sleep within certain boundaries, the circadian rhythm determines its timing. Sleep is not a unitary process. It is composed of at least two substrates, each named after its main distinctive features. One is characterized by the presence of low-amplitude, relatively fast rhythms on electroencephalographic (EEG) recordings and rapid eye movements (REMs), despite global muscular tonus abolition, and is therefore often referred to as REM sleep or paradoxical sleep (PS). The other main sleep type is known as non-REM (NREM) or slow-wave sleep (SWS). It is characterized by large-amplitude, low-frequency EEG oscillations. During the night, SWS and REM sleep periods alternate, following an ultradian rhythm of about 90 to 100 min.

It is now estimated that as many as 40 million Americans, and millions of others around the world, suffer from some type of sleep disruption or disorder, and the numbers are increasing. The potential economic costs to society are enormous and touch many facets of our lives from human health to traffic safety.

In order to treat these pathologies, basic and clinical researchers have seen tremendous advances in the last 40 years. Today new biomedical technologies are advancing our understanding of disease, functions, and regulation of SWS and REM sleep, but much remains to be done to meet the many needs and opportunities of this field. Recent years have seen major discoveries in the circuits responsible for SWS and REM sleep, narcolepsy, and the possible role of sleep in memory and developmental processes.

The aim of this book is to present these and other recent major advances in sleep research obtained by means of emerging new technologies and approaches. In particular, new data obtained by differential gene expression analysis, transgenic mice, and functional imaging are presented. New theoretical concepts about the mechanisms regulating sleep and new theories on its functions are also discussed.

This book should serve as an aid to identify future opportunities in the dynamic and growing field of sleep research. I expect that not only those seriously interested in the field of sleep and sleep disorders but also others in related disciplines will find this textbook valuable in their research and clinical practice.