sleep cycle and sleep stages
- sleep cycle composes of different sleep stages
- normally person goes through 4-6 cycles
- cycle takes about 90-120 minutes
Stages
Awake
- alpha waves: relaxed
- beta waves: active concentration
N1
- first fall asleep
- short
- body not fully relaxed
- brain and body starts to slow
- easy to wake
- as night goes on, sleeper spends less time in stage 1
- theta waves
N2
- more relaxed, slower breath, slower heart rate
- eye movement stops
- brain activity slows
- short bursts of activity: helps wake up by external stimuli
- becomes longer as the night goes
- half of time in spent in N2
- teeth grinding (bruxism)
- K complex and sleep spindles
N3
- deep sleep
- harder to wake up
- even more relaxed
- delta waves or slow wave sleep (SWS)
- maybe critical for body recovery, growth, immune system
- more time in deep sleep earlier, then more time in REM later
- sleep walking and enuresis
REM
- brain activity higher
- paralysis of muscle, penile/clitoral erections
- increased pulse, blood pressure
- eyes move quickly
- essential for cognitive functions
- vivid dreams
- 10-40 min for every 90 min sleep
- REM rebound: body compensates with poor sleep by having higher REM sleep during next period
- sawtooth waves
Normal Changes
1
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