The work is devoted to the study of physiological and mental changes in animals and humans in various isolation conditions. The urgency of the problem of isolation in conditions of loneliness for modern psychology and psychiatry and the lack of generalizing domestic works in this area prompted the authors to write this book. On the basis of literary material and their own experimental data, the authors try to highlight the problem of loneliness in the psychological, psychiatric, philosophical and sociological aspects. The book also includes preventive measures of nervous-mental diseases .. The monograph is intended for psychologists, psychopathologists, physiologists, psychiatrists, and is also of interest to doctors of various specialties.