Rapid eye movement sleep is one of the most distinctive stages of the sleep cycle. During this stage the brain becomes highly active while the body remains mostly still. REM sleep is closely associated with dreaming and plays an important role in cognitive and emotional health.
What happens during REM sleep
REM sleep typically begins about ninety minutes after falling asleep. During this stage several physiological changes occur.
- The brain becomes highly active.
- Eyes move rapidly beneath closed eyelids.
- Breathing becomes irregular.
- Most skeletal muscles temporarily lose their ability to move.
This temporary muscle paralysis prevents the body from physically acting out dreams.
How REM sleep supports memory
REM sleep is strongly linked with memory consolidation. During this stage the brain processes information gathered during the day and strengthens neural connections associated with learning.
Studies have shown that individuals deprived of REM sleep may struggle to retain new information or perform complex tasks requiring memory.
Emotional processing during REM sleep
REM sleep also appears to play a role in emotional regulation. Brain regions associated with emotions, such as the amygdala, remain active during this stage.
Researchers believe REM sleep helps the brain process emotional experiences and maintain psychological balance.
Why REM sleep occurs later in the night
Sleep cycles earlier in the night contain more deep sleep, while cycles later in the night contain longer periods of REM sleep. This pattern allows the body to prioritise physical repair early in the night and cognitive processing later.
References
Stickgold R. Sleep Dependent Memory Consolidation. Nature
Harvard Medical School Division of Sleep Medicine
Walker M. Why We Sleep