Abstract

Sleep is a physiological behaviour, cyclical and reversible, that occupies one third of our lives, even if some consider this time as regrettably wasted. But its ultimate explanation is still unknown, although multiple theories have tried to clarify it throughout the centuries. The issue of sleep and its abnormalities has attracted man’s interest from the beginning of time and many philosophers, poets and artists have addressed the topic. But the actual science of sleep, as we know it today, is relatively young. If we give Hans Berger, the father of electroencephalography, the merit of introducing a new technique to study the brain of the sleeper in 1929, then the history of somnology is less than 100 years old. Another significant discovery was the dichotomy between REM sleep, NREM sleep and their relation to wakefulness, encompassing the three stages of human consciousness. Sleep disorders comprise manifold phenomena affecting not only sleep itself but daytime functioning and some of them can implicate injuries or serious health outcomes. Some of these issues are reviewed in this chapter.