The AHI is the actual measurement of sleep apnea severity from a sleep study, counting how many apnea or hypopnea events occur per hour of sleep — the diagnostic number itself, not a screening estimate.
Normal.
Mild obstructive sleep apnea.
Moderate sleep apnea.
Severe sleep apnea.
No — STOP-BANG estimates the risk of having sleep apnea before testing, while AHI is the measured result from an actual overnight sleep study.
Normal is under 5 events per hour, mild is 5–15, moderate is 15–30, and severe is above 30.
An apnea (near-complete airflow stoppage) or a hypopnea (a partial reduction in airflow with an oxygen drop or arousal), each lasting at least about 10 seconds.
Higher AHI, especially with symptoms or cardiovascular risk, supports therapies like CPAP. Mild disease may be managed with positional or lifestyle measures.