Sleep Study (Polysomnogram)

• An In-lab sleep study measures heart, lung, and brain activity, breathing effort and patterns, arm and leg movements, and oxygen levels. These measures are used to evaluate many aspects of breathing in sleep.
• A home sleep study measures breathing patterns, oxygen levels, and airflow and can also measure sleep apnea severity.
• Apnea Hypopnea Index (AHI) is one measure of sleep apnea severity that is commonly used. It estimates the number of times per hour that airflow stops or is reduced.
  • Normal: AHI < 5
  • Mild apnea: AHI 5-15
  • Moderate: AHI 15-30
  • Severe: AHI >30
• Respiratory Disturbance Index (RDI) incorporates another measure of breathing pattern change into the sleep apnea scoring. This is often best measured with an in-lab sleep study.