What apnoea-hypopnoea index (AHI) value per hour is considered normal?

• A. <5 events/hour.
• B. 5-14 events/hour.
• C. 15-29 events/hour.
• D. ≥30 events/hour.

Answer: (A)

The key idea is what the apnoea-hypopnoea index (AHI) tells us about breathing during sleep. AHI counts how many times per hour breathing is disrupted by either a complete stop (apnea) or a partial reduction (hypopnea). Normal breathing is defined as having very few of these events, usually fewer than five per hour in adults. That threshold is what separates normal from sleep-disordered breathing. When the AHI climbs above this level, the categories rise: mild sleep apnea starts around five per hour, moderate around fifteen, and severe around thirty or more. So, less than five events per hour best matches a normal result.