Stages of Sleep
Art & Research: Xiaoying Wu
Further Reading Literature: Xiaoying Wu
Stages of Sleep
Stage 1: N1 (NON-REM)
The N1 stage is the transition from wakefulness to sleep (NINDS). People are easily woken up in this state. Alpha waves and theta waves are produced in the brain, which are low frequency waves that cause relaxation and drowsiness (NCBI). The brain waves, heartbeat, breathing, and eye movement begin to slow down (NINDS). Some people may experience sudden muscle contractions in this stage (American Sleep Association).
Stage 2: N2 (NON-REM)
The N2 stage is a period of light sleep where theta waves begin to appear (NINDS). There are bursts in brain activity called sleep spindles, and K-complexes appear to signify transition to deeper sleep (NCBI). K-complexes are large brain waves that help with arousal to maintain sleep (NCBI). Heart rate and breathing slows down more (NINDS). The body’s temperature lowers and eye movement stops (NINDS).
Stage 3: N3 (Non-REM)
The N3 stage is when deep sleep occurs (NINDS). Slow waves called delta waves increase in the brain, making it difficult to wake up the person (American Sleep Association). Heart rate and breathing reaches its lowest in this stage, and the muscles become fully relaxed (NINDS).
Stage 4: R (REM)
The R stage is the REM period where dreams occur (NCBI). This stage is important for memory skills as it stimulates the brain to send signals to the thalamus, then to the cerebral cortex; the cerebral cortex is the brain region responsible for “learning, thinking, and organizing information” (UPMC). As indicated in the name, rapid eye movement (REM), the eyes rapidly move during this sleep stage. Heart rate and breathing increases, while the limb muscles become temporarily paralyzed (NINDS).
The importance of sleep
During sleep, our body grows/recovers by producing and breaking down proteins (American Sleep Association). Adults should be getting 7-9 hours of sleep per night (American Sleep Association). Make sure you are getting the sufficient amount of sleep every night to properly recover from your day of work!