What sleep is in our everyday life is probably not worth telling. Some people get enough sleep, some don’t, but one way or another, every person who is tired during the day dreams of a soft pillow. From a medical point of view, sleep is our adaptation, a state that, through certain neurophysiological, chemical, psychological changes, gives us the opportunity to be physically, mentally and emotionally functional the next day. Sleep is a clear sequential process of changing phases, stages of electrical activity of the brain. The stages of sleep are largely determined by the set of our genes and, interestingly, not all animals are endowed with the ability to sleep in the sense in which we are accustomed to perceiving sleep.
First things first
Complete, true sleep with phases and stages is characteristic only of the most developed warm-blooded animals: mammals (which include humans) and birds. The variety of phases and stages, their duration and depth in different animals is amazing. Some people sleep a few minutes a day, with changes in sleep stages occurring within seconds, as, for example, in the case of a giraffe. And in some species of bats, sleep can last up to 20 hours.
The separation of phases began relatively recently. The science of somnology itself began to take shape just over 80 years ago. Alfred Lee Loomis first described the stages of sleep in the mid-30s of the last century, then in 1953 scientists Dement and Kleitman identified the phase of rapid eye movements, and in 1968 all knowledge was combined by Rechtschaffen into one atlas, which was used by all sleep doctors until 2007, when numerous changes occurred. New methods of examining patients were developed. A path has been passed from the application of several electrodes (electroencephalography) with recording of signals in ink on paper to complex computer systems that, in addition to the electrical activity of the brain, make it possible to simultaneously evaluate many parameters of our body.
