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Sleep Study Level 2

(Polysomnography Level 2)

A sleep study (polysomnography) is a diagnostic test used to evaluate sleep patterns, disorders, and physiological functions during sleep. It is typically conducted in a sleep lab or at home, depending on the type and severity of the suspected sleep disorder. Below is a detailed breakdown:

Types of Sleep Studies

  1. In-Lab Polysomnography (Level 1)
    • Gold standard for diagnosing sleep disorders.
    • Conducted in a sleep clinic or hospital.
    • Measures:
      • Brain waves (EEG)
      • Eye movements (EOG)
      • Muscle activity (EMG)
      • Heart rate (ECG)
      • Breathing patterns (nasal airflow, chest/abdominal effort)
      • Oxygen levels (pulse oximetry)
      • Limb movements
      • Snoring and body position
    • Used for: Diagnosing sleep apnea, narcolepsy, restless legs syndrome (RLS), parasomnias (e.g., sleepwalking), and insomnia.
  2. Home Sleep Apnea Testing (HSAT) (Level 2, 3)
    • Portable devices used at home to primarily assess obstructive sleep apnea (OSA).
    • Levels:
      • Level 2: Measures 7+ parameters (similar to in-lab, but less comprehensive).
      • Level 3: Limited-channel devices (e.g., airflow, oxygen, effort, heart rate).
    • Advantages: Convenient, lower cost.

Why Are Sleep Studies Done?

  • Diagnose sleep apnea (obstructive or central).
  • Evaluate insomnia or unexplained daytime sleepiness.
  • Detect parasomnias (e.g., night terrors, REM sleep behavior disorder).
  • Assess narcolepsy or hypersomnia.
  • Monitor treatment efficacy (e.g., CPAP for sleep apnea).

Procedure

  1. Preparation:
    • Avoid caffeine/alcohol before the test.
    • Follow your normal sleep routine unless instructed otherwise.
    • Sensors are attached to your body (scalp, face, chest, legs).
  2. During the Study:
    • In-lab: Sleep in a private room while technicians monitor data.
    • At-home: Wear a portable device and follow instructions.
  3. After the Study:
    • Data is analyzed by a sleep specialist.
    • Results are reviewed in a follow-up appointment.

Key Metrics Analyzed

  • Apnea-Hypopnea Index (AHI): Number of breathing pauses per hour (diagnoses sleep apnea severity).
  • Oxygen Desaturation: Drops in blood oxygen levels.
  • Sleep Stages: Time spent in REM vs. non-REM sleep.
  • Limb Movements: Frequency of restless legs or periodic limb movements.

Interpretation of Results

  • Normal: AHI <5, regular sleep stages, no significant oxygen drops.
  • Mild Sleep Apnea: AHI 5–15.
  • Moderate Sleep Apnea: AHI 15–30.
  • Severe Sleep Apnea: AHI >30.

Who Needs a Sleep Study?

  • Loud snoring or gasping during sleep.
  • Daytime fatigue despite adequate sleep.
  • Witnessed breathing pauses (reported by a partner).
  • Unexplained insomnia or frequent awakenings.

Risks and Limitations

  • Discomfort: Sensors/wires may feel intrusive.
  • False Negatives: Home tests may miss mild or complex cases.
  • Cost: In-lab studies are more expensive (insurance coverage varies).

Follow-Up and Treatment

  • Sleep Apnea: CPAP, BiPAP, oral appliances, or surgery.
  • Insomnia: Cognitive behavioral therapy (CBT-I), medication.
  • Narcolepsy: Stimulants, sodium oxybate.