What does the Apnea-Hypopnea Index (AHI) measure?

The Apnea-Hypopnea Index (AHI) specifically quantifies the severity of sleep apnea by calculating the average number of apneas (complete cessation of breathing) and hypopneas (partial cessation of breathing) that occur per hour of sleep. AHI is a crucial metric used in sleep studies to help diagnose the condition and determine the appropriate level of treatment.

In the context of sleep apnea, a higher AHI indicates more severe episodes of interrupted breathing, which can significantly impact a person's health and quality of sleep. Clinicians use the AHI to categorize sleep apnea into different severity levels—mild, moderate, or severe—allowing for tailored treatment approaches.

While other options touch upon aspects related to sleep, they do not pertain directly to the AHI's primary function. For example, duration of sleep focuses on how long an individual is asleep, oxygen saturation levels relate to the amount of oxygen in the blood during sleep, and heart rate variability during sleep measures fluctuations in heart rate but does not directly correlate with breathing interruptions. These factors can be important in the assessment of sleep disorders, but they are distinctly different from what the AHI measures.