Physiology of Sleep

By Bikash Paul

scientists believed that sleep is a physiological state characterized by the loss of active mental connections of the subject with the outside world. However, now physiologists consider sleep as the most important process of life, during which brain activity often exceeds daytime levels.

 

The book presents data on the physiological significance, phases, and evolution of sleep, discusses the mechanisms that ensure the regulation of sleep, sleep disorders, and highlights the features of sleep in various animal species and humans.

• Language: English
• Publisher: Bikash Paul
• Release date: Aug 16, 2022
• ISBN: 9798201935214

Bikash Paul

Close the door. Write with no one looking over your shoulder. Don’t try to figure out what other people want to hear from you; figure out what you have to say. It’s the one and the only thing you have to offer. Bikash Paul from India is a content writer and digital marketer, also working with My Recharge Ayurveda for several years. I helped people solve their problems. My education qualification is MBA in marketing and an HR minor. Writing books is another profession.

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INTRODUCTION

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In recent years, ethology, the science of behavior, has become increasingly important in the study of the physiology of farm animals. Since sleep is one of the main periodically emerging states of the body, knowledge about it allows one to correctly understand the behavioral features of animals and humans, the mechanisms that ensure the regulation of various body functions, and the endogenous component of biological rhythms. All of this enables veterinarians to correctly diagnose, prevent and treat diseases, and zoo engineers to provide physiologically sound conditions for keeping animals and their exploitation in accordance with the capabilities of the body.

The nature of sleep has always aroused great interest and served as an occasion for many conjectures and assumptions. This is not surprising, since a person spends a third of his life in a dream. In ancient cultures, there were various deities who patronized sleep. In Greek mythology, the god of sleep was called Hypnos, in Roman mythology Somnus. Morpheus, the god of dreams, was one of the thousand sons of Somnus. The god of sleep was considered the brother of the god of death, and both of them were sons of the goddess of the night.

The study of the problem of sleep has a rather long history, but information on this issue was first summarized only in 1893 by M. M. Manaseina, who, in essence, is the founder of the science of sleep - somnology. The first clinical and morphological studies of the role of damage to certain areas of the brain is the origin of pathological drowsiness belong to the French researcher Gaye (C. J. A. Gayet, 1875) and the Austrian doctor Mautner (L. Mauthner, 1890).

Tii made a great contribution to the physiology and pathology of the states of wakefulness and sleep. Economo showed in 1926, using the example of lethargic sleep in epidemic encephalitis, the importance of mesencephalo-hypothalamic structures in maintaining wakefulness and sleep. Later, in the 30-40s. In the 20th century, experiments on animals confirmed the importance of the structures of the mesencephalic-hypothalamic junction in ensuring wakefulness and the preoptic zone of the hypothalamus in the genesis of sleep.

A fundamentally new stage in research in the field of the problem of sleep was the work of IP Pavlov and his collaborators. In accordance with his theory of higher nervous activity, I. P. Pavlov considered sleep as a diffuse cortical inhibition, believing that internal inhibition and sleep are, on a physical and chemical basis, one and the same process.

In 1944, the Swiss physiologist W. Hess discovered that electrical stimulation of the visual tubercles caused in experimental animals behavioral sleep that did not differ in external manifestations from natural sleep.

For many centuries, sleep was considered precisely in terms of external signs, i.e. state of rest and reduced reactivity. Even the formation of ideas about two states inside natural sleep, fundamentally different from each other and from wakefulness (slow-wave and paradoxical phases), could not interfere with such an approach. Recently, however, an increasing number of facts have appeared that do not fit into such ideas.

Similarly, we can consider such a generally accepted characteristic of sleep as unresponsiveness, i.e. mental retardation, and lack of response to external stimuli. Firstly, this is an a posteriori sign of sleep, since the awakening threshold can only be determined by waking a person. Secondly, unresponsiveness, like immobility, is not a sufficient sign, since it is characteristic of a number of diseases and other pathological conditions: pharmacological sleep, anesthesia, coma, etc.

The next stage in the development of ideas about the mechanism of sleep is associated with an analysis of the role of the brainstem reticular formation in the mechanisms of brain activity. In the studies of J. Loruzzi and X. Megun (1949), the ascending activating influences of the reticular formation of the brainstem and hypothalamus on the overlying sections in maintaining wakefulness were found to be of great importance. In this case, sleep was considered as a consequence of a temporary blockade of ascending activating influences with the simultaneous switching on of thalamocortical synchronizing processes. Somewhat later, the role of the caudal parts of the brain stem in the onset of sleep was shown. These studies laid the foundation for the development of ideas about the active nature of sleep, which was then confirmed in experiments on animals, as well as on humans.

The emergence of electroencephalography in the second half of the XX century. made it possible, finally, to strictly delineate the phases of sleep and thereby approach the elucidation of their physiological role. Physiologists identify sleep, its phases, and stages on the basis of generally accepted, so-called polygraphic criteria, polygrams - registration of brain electrical activity - electroencephalogram (EEG), muscle activity - electromyogram (EMG), eye movements - electrooculogram (EOG). Currently, rhythm is considered a necessary and sufficient sign of sleep, i.e. the alternation of certain physiological signs (printing pictures) that make it possible to distinguish normal sleep from monotonous dream-like states.

Modern research has greatly enriched the understanding of sleep. In laboratories that study sleep, special conditions are created to assess the effect of certain factors (experimental variables) on sleep. The studies are carried out in a sound-insulated, temperature-controlled room, and the data obtained are based on objective measurements and continuous monitoring. Monitoring is usually carried out at night for 8 hours. Such studies are important for diagnosing and treating sleep disorders, as well as for analyzing the effects of drugs on the central nervous system.

1.SLEEP AND ITS PHYSIOLOGICAL SIGNIFICANCE

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SLEEP (Somnus) is a special genetically determined functional state of the brain and the whole organism of humans and animals, which has specific qualitative features of the activity of the central nervous system and the somatic sphere that are different from wakefulness, characterized by inhibition of the active interaction of the organism with the environment and the incomplete cessation of the conscious mental activities. Physiological sleep differs from dream-like states - coma, stupor, anesthesia, hibernation, and hypnosis - in that it occurs under the influence of internal rather than external factors, and it retains the ability to awaken.

Sleep is as much a need as being awake. The alternation of sleep and wakefulness is a necessary condition for the life of the body. These are two states of the body aimed at optimizing the life regime. The general meaning of sleep can be defined as a physiological restoration of functions under conditions of introverted consciousness when there is a temporary disconnection from external information, and the conscious filter does not interfere with the analysis of information, it is ordered, stored in long-term memory.

Sleep in many animals is confined to the daily change of day and night (monophasic sleep), while in other animals, for example, in mammals from the order of carnivores, the change of sleep and wakefulness occurs several times a day (polyphasic sleep). In some animals,