About every one and a half hours sleepers fall into a strange state: The heart beats faster, the respiratory rate and blood pressure rise, the eyes wander with their eyelids closed - the REM phase has begun. The discovery of REM sleep is only about 50 years back. The research team led by sleep researcher Nathaniel Kleitmann discovered the REM phases in 1953 in a sleep laboratory in Chicago set up by him.
NON REM and REM phases
Our sleep is not the same throughout the entire time - it runs in phases that repeat several times during the night. The sleep is divided into five phases, which can be distinguished by differently pronounced brain waves: the NON-REM phases with the stages 1 to 4 and the so-called REM phases (English: Rapid Eye Movement), by rapid movement of the eyes are marked under the eyelids. While deep sleep is largely attributed the task of physical regeneration, sleep researchers believe that REM sleep is necessary for mental recovery. The role of fast eye movements is still not fully understood in sleep research today.
The REM phase
During REM sleep, we have the most and the most intense dreams - so this sleep stage is also called the dream phase. The eye movements are then particularly strong, heartbeat, blood pressure and breathing are faster and more irregular, signs of sexual arousal are also noted. In the REM phase, the electroencephalogram indicates increased activity, but at the same time the muscle tone is greatly reduced. This process is actively controlled by our brain. Without the lowered muscle tone, the sleeper would actually perform all the dreamed movements, which of course would be fatal. Who is awakened from the REM sleep, can remember his dreams particularly well. In sleep of 8 hours, 3-6 REM phases are found, which is about 20% of the total sleep time.
If you wake up several nights in a row (at least 4 nights) from the REM sleep, the percentage REM increases in the undisturbed nights from 20% to 27% to 29%. This effect is called REM rebound effect.