AP Psychology Stages of Sleep

NREM Stage 1

alpha and theta waves

NREM Stage 2

theta and start of delta waves

NREM Stage 3 and 4

delta brain waves

REM sleep

beta brain waves

NREM Stage 1

lasts only a few minutes, person quickly gains consciousness, experiences hypnagogic hallucinations, vivid sensory experiences, sometimes/usually accompanied by a myoclonic jerk that often awakes the person

NREM Stage 2

start of true sleep, sleep spindles in EEG patterns - sudden bursts of brain activity

NREM Stage 3

considered this stage when 20% of brain activity shows delta waves, referred to as slow-wave sleep

NREM Stage 4

considered this stage when delta waves exceed 50% of brain activity. Person does not experience sensory stimulation - hard to wake up, referred to as slow-wave sleep

REM sleep

brain activity becomes more active, resembling that of an awakened state; approximately 85% of dreams occur during this stage. eyes move rapidly back and forth beneath eyelids