What apnoea-hypopnoea index (AHI) value defines severe sleep apnea?

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

Answer: (D)

AHI is the measure used to gauge how severe sleep apnea is, by counting the average number of breathing pauses (apneas) plus partial reductions (hypopneas) per hour of sleep. Based on these counts, sleep specialists categorize severity: fewer than 5 is normal, 5 to 14 is mild, 15 to 29 is moderate, and 30 or more is severe. Therefore, an AHI of 30 or more events per hour defines severe sleep apnea, reflecting very frequent breathing disruptions during sleep and greater associated health risks, which often necessitate more intensive treatment.