What is REM sleep?

The brain cycles through five distinctive phases: phase 1, 2, 3, 4, and rapid eye movement (REM) sleep. REM sleep represents 25% of the sleep cycle and first occurs 70 to 90 minutes after falling asleep. Since sleep cycles repeat, you enter REM sleep several times during the night. During REM sleep, the brain and body are energized and this is when we dream.1 It is considered that REM sleep participates in the process of storing memories and learning and also helps balance the mood,2 although it is not They understand the exact mechanisms well. REM sleep is initiated in response to signals sent to and from different regions of the brain. The signals are sent to the cerebral cortex, which is responsible for learning, thinking and organizing information. Signals are also sent to the spinal cord to stop movements, creating a temporary inability to move the muscles ("paralysis") of the arms and legs. An abnormal alteration of this temporary paralysis can cause people to move while dreaming. This type of movement during sleep can cause injuries, for example when a person bumps into furniture while dreaming about catching a ball.3 REM sleep stimulates brain regions used for learning. Studies have shown that when people are deprived of REM sleep, they fail to remember what they were taught before going to sleep.3 Lack of REM sleep has also been linked to conditions such as migraines.2 It is not known why we dream during REM sleep. While some of the signals sent to the cerebral cortex during sleep are important for learning and memory, other signals appear to be sent randomly. The cerebral cortex may try to interpret or make sense of these randomly sent signals and create a “story,” resulting in dreams.3