Physiology in Sleep
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Physiology in Sleep Section Gilles Lavigne 4 17 Relevance of Sleep 21 Respiratory Physiology: 26 Endocrine Physiology in Physiology for Sleep Central Neural Control Relation to Sleep and Medicine Clinicians of Respiratory Neurons Sleep Disturbances 18 What Brain Imaging and Motoneurons during 27 Gastrointestinal Reveals about Sleep Sleep Physiology in Relation to Generation and 22 Respiratory Physiology: Sleep Maintenance Understanding the 28 Body Temperature, 19 Cardiovascular Control of Ventilation Sleep, and Hibernation Physiology: Central and 23 Normal Physiology of 29 Memory Processing in Autonomic Regulation the Upper and Lower Relation to Sleep 20 Cardiovascular Airways 30 Sensory and Motor Physiology: Autonomic 24 Respiratory Physiology: Processing during Sleep Control in Health and in Sleep at High Altitudes and Wakefulness Sleep Disorders 25 Sleep and Host Defense Relevance of Sleep Physiology for Chapter Sleep Medicine Clinicians Gilles Lavigne 17 Abstract a process that is integral to patient satisfaction and well The physiology section of this volume covers a wide spectrum being. A wider knowledge of physiology will also assist clini- of very precise concepts from molecular and behavioral genet- cians in clarifying new and relevant research priorities for ics to system physiology (temperature control, cardiovascular basic scientists or public health investigators. Overall, the and respiratory physiology, immune and endocrine functions, development of enhanced communication between health sensory motor neurophysiology), integrating functions such as workforces will promote the rapid transfer of relevant clinical mental performance, memory, mood, and wake time physical issues to scientists, of new findings to the benefit of patients. functioning. An important focus has been to highlight the At the same time, good communication will keep clinicians in relevance of these topics to the practice of sleep medicine. A step with the expanding field of sleep medicine and will make keener understanding of physiological dysfunction helps clini- them well prepared to face the growing challenges in public cians to explain to patients how to cope with a sleep disorder, health issues. Why do doctors and scientists need to understand sleep physiology has resulted in innovations in the pharma- physiology? A thorough knowledge of sleep physiology is ceutical industry and in the design of diagnostic and central to improved accuracy and validity in the develop- therapeutic devices (e.g., recording and scoring systems, ment of diagnostic tools, to making innovations in patient continuous positive airway pressure, mandibular advance- management, and to keeping abreast of leading edge devel- ment appliances). But governmental agencies only grant opments in sleep medicine. For some clinicians, reading permission to market a given product following epide- chapters in sleep physiology may recall early years of train- miological findings, explorations of physiological and ing, but these days physiology is an integral part of many pathological mechanisms, and randomized control trials advancements in clinical practice (e.g., breathing and car- demonstrating efficacy and safety. The absence of objec- diovascular measurements, brain imaging), and it forms tive and valid measures to assess sleep improvement and the basis of translating genetics and proteomics into inno- safety can prevent developments and innovation from vation in diagnosis and therapeutics. being integrated into sleep medicine practices. Although The impact of poor sleep and of several sleep disorders questionnaires are used to screen patients for many sleep on societal and economic health is interrelated1; health disorders, it is the physiological (e.g., hormonal-endocrine governmental agencies are extremely sensitive to discover- release, heart rate by electrocardiogram, brain activity by ies that may improve the population’s quality of life and electroencephalography) and psychophysiological (reac- reduce health care costs. A greater understanding of sleep tion time, multiple sleep latency test, sensory perception) L 199 200 PART I / Section 4 • Physiology in Sleep measures that confirm the accuracy and validity of the understanding the clinical disorders described in this concepts. volume. In other words, we hope they will provide some Clinical science progresses sequentially. For example, answers about how disease affects physiology, how inter- using questionnaires, the prevalence of nonrestorative ventions work, why they do not work, and what remains sleep has been reported at 10% in the general population.2 to be done. Future editions of this volume will probably With polygraphy, the consequences of that nonrestorative integrate more knowledge on the relevance of nano infor- sleep consequences are characterized,3,4 interindividual mation, such as molecular and synaptic homeostasis,12 trait differences may be identified,5 and phenotypic deter- micro information, such as how tractography imaging is minants of vulnerability also recognized.6 used to assess cortical and brainstem networking activity The identification of gene polymorphism related to spe- during sleep or using mathematical modelling,13 and macro cific sleep disorders is another domain of intense interest information that integrates behavior with sleep disorders (see Section 3 of this volume). We are already in the post- and addresses issues related to cognition and placebo influ- genomic era with the advent of proteomics: the science of ence on sleep.14-17 protein characterization in relation to biological activity or 7 disorder/disease. Most sleep disorders, such as insomnia, REFERENCES sleep breathing disorders (e.g., sleep apnea), parasomnia 1. Léger D, Pandi-Perumal SR, editors. Sleep disorders—their impact (e.g., sleepwalking, enuresis, REM behavior disorder on public health. London, UK: Informa Healthcare; 2007. [RBD]), sleep-related movement disorders (e.g., restless 2. Ohayon M. Prevalence and risk factors of morning headaches in the leg syndrome/periodic limb movement), and circadian general population. Arch Intern Med 2004;164:97-102. rhythm sleep disorders have genetic and/or molecular 3. Bonnet MH, Arand DL. Clinical effects of sleep fragmentation 8,9 versus sleep deprivation. 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