What are REM phases?

About every hour and a half, people who are asleep fall into a strange state: the heart beats faster, the respiratory rate and blood pressure rise, the eyes wander back and forth with the lids closed – the REM phase has begun.  REM sleep was only discovered about 50 years ago. The research team led by sleep researcher Nathaniel Kleitmann discovered the REM phases in 1953 in a sleep laboratory he set up in Chicago.

NON REM and REM phases

Our sleep is not the same depth all the time – it happens in phases that are repeated several times during the night. Sleep is divided into five phases, which can be distinguished by brain waves of different strengths: the NON-REM phases with stages 1 to 4 and the so-called REM phases (English: Rapid Eye Movement), which are caused by rapid movement of the eyes marked under the lids. While deep sleep is widely credited with helping the body recover, sleep researchers believe REM sleep is necessary for mental recovery. There is still no consensus in sleep research on the role played by rapid eye movements.

Die REM-Phase

During REM sleep we have the most and the most intense dreams – that’s why this sleep stage is also known as the dream phase. Eye movements are then particularly strong, heartbeat, blood pressure and breathing become faster and more irregular, and there are also signs of sexual arousal. In the REM phase, the electroencephalogram shows increased activity, but at the same time the muscle tone is greatly reduced. This process is actively controlled by our brain. Without the reduced muscle tone, the sleeper would actually carry out all the dreamed movements, which would of course be fatal. Those who are woken up from REM sleep are particularly good at remembering their dreams. In 8 hours of sleep, 3-6 REM phases are found, which is about 20% of the total sleep time.

sleep deprivation

If you wake up from REM sleep several nights in a row (at least 4 nights), the percentage of REM in the undisturbed nights increases from 20% to 27% to 29%. This effect is known as the  REM rebound effect .


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