Although our body rests during sleep, our body functions don’t just get turned off. Some organs reduce their work, others are even more active than during the day. To regulate all natural processes the brain works at full blast.
Sleep science differentiates five different sleeping phases in total. The non-REM-sleep (orthodox or synchronous sleep) has four sleep stages: the phases of falling asleep and light sleep in which even soft sounds may wake up a sleeping person, as well as middle and deep sleep.
REM-sleep (paradoxical or asynchronous sleep):
REM is the abbreviation for “Rapid Eye Movement”. In this dream-active phase, heavy eye-movements are recognizable underneath the closed eyelids. During this sleeping phase, our brain processes daily events, sorts information, saves new and erases old learning contents, especially motoric skills. Out of this reason, REM-sleep plays an important role for our memory. When someone gets woken up during this sleeping phase he normally remembers his dreams.
These phases and “wave motions” are repeated three to five times per night. The depth of the sleep decreases, the duration of dreams increases during the night.
Course of the stages
After a short period of calm wakefulness the phase of falling asleep starts. After 60 to 90 minutes the sleeping person is wandering through the different sleeping stages without waking up. “This night-time pattern is just as universal as sleep is and just as regular like the movements of the planets”, so the American Dr. Diamond. But, the deepest sleep is not the most restful one. During REM-sleep we are completely relaxed, measurements of the electric brain activity showed that the brain is very active during this phase and rather resembles the waking state than the other sleep -– out of this reason, this phase is also called “paradoxical sleep” (in contrast to “orthodox sleep”). At the same time, during these REM-phases the responsiveness for outer stimuli is nearly zero. The younger a human being is the more time he spends in REM-sleep.
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