Psych Unit 3 Sleep (REM & NREM, Stages of Sleep)
REM Sleep
• A period of REM sleep of rapid eye movement sleep during which the eyeballs rapidly move beneath the closed eyelids, darting back and forth and up and down in jerky movements. • The EEG shows irregular brain wave patterns with short, high frequency beta waves like NWC however it's considered a deep stage of sleep because individual is hard to arouse. • The body's internal function is more active during REM sleep than NREM sleep. Heart rate is faster and more irregular, blood pressure rises and breathing is quicker and more irregular. • Adults spend approx. 20% of sleep time in REM sleep. Young babies spend up to 50% of their total sleep time in REM sleep, although this levels out to 20% by approximately 5 years of age. • Young babies spend a larger proportion of their total sleep in REM sleep is that REM sleep pays an important role in the MATURATION of the nervous system.
NREM Sleep
• Approx. 80% of the time is spent asleep is in NREM sleep. • The first half of the night has more NREM sleep than the second half.
Stage 1 of NREM Sleep
• Decreased heart rate, respiration, body temperature and muscle tension. • Stage 1 is when the sleeper may experience a hypnic jerk. Hypnic jerks are quite common in stage 1. • Approximately 5-10 minutes. • EEG pattern shows a decrease in ALPHA WAVE production as these brain waves are replaced by more irregular, medium frequency, THETA WAVES, which have a mixture of high and low amplitude.
Stage 2 of NREM Sleep
• Light stage of sleep. • Stage 2 lasts about 10-20 minutes. •Body movement lessens, breathing becomes regular, heart rate, blood pressure and temperature continues to fall. • In Stage 2 EEG shows SLEEP SPINDLES (brief bursts of high frequency periodically appear. The presence of these indicate that the person is truly asleep. • EEG patterns also show K COMPLEXES, which are bursts of low frequency and slightly higher amplitude waves. • EEG shows THETA WAVES (although lower in frequency and higher in amplitude than STAGE 1.)
States or Types of Sleep
NREM sleep and REM sleep.
Stage 4 of NREM Sleep
• Deepest stage of sleep. When muscles are completely relaxed and movement is minimal. • DELTA WAVES dominate the EEG pattern and are even slower and larger than in STAGE 3. • When the EEG shows that DELTA WAVES comprise more than 50%, the person has entered STAGE 4, the deepest stage of sleep. • Moving through the sleep cycle from STAGE 1 to STAGE 4 takes about 45-60 minutes before progressively moving back up through STAGES 3, 2, and then 1. • During the very deep sleep of STAGES 3 and 4 is when sleep phenomena, such as sleepwalking, sleep talking and night terrors occur.
Stage 3 of NREM Sleep
• Stage 3 is a moderate deep sleep stage and lasts for approximately 10 minutes. • Heart rate, blood pressure and body temperature still continue to drop and breathing becomes slow and steady. • An individual is external relaxed and becomes less and less responsive to external stimuli. • EEG shows reduction in brain activity and DELTA WAVES appear. DELTA WAVES make up 20-50% of the brain waves recorded during STAGE 3. They are lower in frequency and higher in amplitude than the alpha and theta waves of STAGE 1 and 2.
