Sleep HealthFebruary 18, 2026·4 min read
By the CIRRUS Editorial Team — how we write and source this
The AHI number explained: mild, moderate, and severe sleep apnea
Your sleep study report boils down to one number. Here's what it's actually counting.
AHI stands for Apnea-Hypopnea Index — the average number of breathing interruptions per hour of sleep, combining full pauses (apneas) and partial reductions in airflow (hypopneas) that also drop blood oxygen or trigger a brief arousal.
The standard severity bands: mild is 5–15 events per hour, moderate is 15–30, and severe is above 30. A count above 30 means, on average, a breathing disruption roughly every two minutes of sleep.
AHI alone doesn't fully capture symptom burden — some people with a moderate AHI feel significantly impaired, while others with a similar number feel comparatively fine, which is why treatment decisions weigh oxygen desaturation levels and daytime symptoms alongside the raw count.
The number also isn't fixed for life. Weight change, alcohol use, sleep position, and nasal congestion can all shift AHI meaningfully between studies, which is part of why a repeat study is sometimes warranted after a significant life change.
This article is general health information, not medical advice, and doesn’t replace evaluation by your own physician. Talk to a doctor about anything specific to your own diagnosis or treatment.