Chapter 33: Rest and Sleep
➢ Physiology of Sleep
○ RAS and bulbar synchronizing region control cyclic nature of sleep
○ RAS facilitates voluntary movements and cortical activities related to alertness
○ RAS relays im
...
Chapter 33: Rest and Sleep
➢ Physiology of Sleep
○ RAS and bulbar synchronizing region control cyclic nature of sleep
○ RAS facilitates voluntary movements and cortical activities related to alertness
○ RAS relays impulses into cerebral cortex and spinal cord
○ During sleep
■ RAS receives few stimuli from cerebral cortex and body
○ Wakefulness
■ RAS activated with stimuli from the cerebral cortex from periphery sensory organs and cells
■ Pain, pressure and noise produce wakefulness via organs and cells
○ Hypothalamus
■ Control center for sleeping and waking
■ Injury causes abnormally long sleeping periods
○ Neurotransmitters
■ Involved with sleeping process
○ Excitatory neurotransmitters
■ Norepinephrine
■ Acetylcholine
■ Dopamine
■ Serotonin
■ Histamine
○ Inhibition
■ Gamma-aminobutyric acid (GABA)
➢ Circadian Rhythms
○ Exists in plants, animals, and humans
○ Full cycle every 24 hours
○ Can fluctuate (depending on rhythms)
■ Heart rate
■ Blood pressure
■ Body temperature
■ Hormone secretions
■ Metabolism
■ Performance
■ Mood
○ Circadian synchronization
■ When physiologic and psychological rhythms are high or most active → person is awake
■ Opposite → person is asleep
■ Light and dark are powerful regulators
■ Chronodisruption
■ Night Shift chronodisruption
➢ Stages of Sleep
○ Polysomnogram: EEG, EOG, and EMG
○ NREM sleep
■ 75% of total sleep
■ Stage 1 → 5% of total sleep
■ Stage 2 → 50-55%
■ Stage III and IV → 10 % each
■ PNS dominates and decreases:
● Pulse
● Respiratory rate
● Blood pressure
● Metabolic rate
● Body temperature
○ REM sleep
■ Difficult to arouse than NREM
■ 20 - 25 % of nightly sleep
■ Dreams occur during this stage
■ Increases:
● Pulse
● RR
● BP
● Metabolic rate
● Body temperature
■ Decreases:
● Deep tendon reflexes
● Skeletal muscle tone
■ REM rebound
➢ Sleep Cycle
○ Consecutively passes through NREM
○ Pattern is then reversed IV → III → II → REM → II → III + IV
○ Once returned to sleep → return to sleeping starting at stage I
○ Four or five cycles of sleep each night
○ Each cycle lasts 90-100 on average
○ More deep occurs in delta stage NREM stages III and IV in first
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