Neuro – EP

Master answer

Stages of sleep

• Slow-wave
  • Deep, restful sleep occuring during first hour
  • Stage I
    • As person drifts to sleep
    • α waves replaced by theta waves of low frequency (4~8Hz)
  • Stage II
    • Occasional bursts of high frequency waves (sleep spindles)
  • Stage III
    • High voltage, low frequency (1~2Hz) δwaves with bursts of high frequency K complexes
  • Stage IV
    • Deepest sleep
    • High voltage δ waves
• REM
  • Rapid Eye Movements
    • Occurs every 90 minutes and lasts 30 minutes
    • β brain waves resembling alert wakefulness

Respiratory changes during sleep

• Tidal volume
  • Declines progressively as slow wave sleep progresses → minimal in REM sleep
  • V_t 25% of awake volume during REM sleep
• Respiratory Rate
  • Remains relatively unchanged
  • Irregular pattern during REM sleep
• Response to pO₂ and pCO₂ dampened
  • PaCO₂ increases 3mmHg
  • PaO₂ decreases 3mmHg
• Upper airway resistance
  • Increased
    • Especially in REM sleep
    • At hypopharynx and soft palate
  • Loss of tonic activity of tensor palati

Sakurai 2016

Answer by Sakurai