II. Physiology

  1. Sleep Stages defined by Electroencephalogram changes

III. Epidemiology

  1. Sleep cycles normalize after 6 months of age
  2. Average sleep per day
    1. Infants and children: 16 to 20 hours per day
    2. Young Adults: 7 to 8 hours per day
    3. Adults over age 60 years: 6.5 hours per day

IV. Stages: Light Sleep (Non-REM Sleep)

  1. Stage I of Sleep: Sleep Onset (Drowsy Phase)
    1. Lowest threshold for arousal
    2. Time spent in Stage I increases with age
      1. Accounts for more brief awakenings
      2. Accounts for fragmented sleep
  2. Stage II of Sleep: Light Sleep

V. Stages: Deep Sleep or Delta Sleep (Non-REM Sleep)

  1. General (Stages 3 and 4)
    1. Deepest, most refreshing and restorative sleep type
    2. Diminishes with age
    3. Highest threshold for arousal
    4. Associated with diffuse dreams
      1. Dream about color or emotion
    5. Associated Conditions
      1. Night Terrors (Sleep Terrors)
      2. Sleep Walking
      3. Confusion on arousal
  2. Stage III of Sleep
  3. Stage IV of Sleep

VI. Stages: Rapid Eye Movement Sleep (REM Sleep)

  1. Timing
    1. REM occurs cyclically every 90 minutes of sleep
    2. Infants spend 50% of sleep time in REM Sleep
    3. Adults spend 20% of sleep time in REM Sleep
  2. Dream Characteristics
    1. Most recallable dreams during this stage
    2. Bizarre and detailed dreams during this stage
  3. Signs
    1. Suppressed voluntary motor activity ("paralyzed")
    2. Rapid eye movements
  4. Associated Sleep Conditions
    1. Nightmares and Frightening Dreams
    2. Sleep-related painful Erections
  5. Provocation of Medical Symptoms
    1. Coronary Artery Disease (Angina)
    2. Chronic Obstructive Pulmonary Disease (Apnea)
    3. Peptic Ulcer Disease (Abdominal Pain)
    4. Gastroesophageal Reflux Disease (Abdominal Pain)
    5. Migraine Headache or Cluster Headache

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