AHI (Apnea-Hypopnea Index)
Calculate events per hour. Understand your sleep study.
AHI result
Display capped at 45; thresholds use the full calculated value.
PAP assessment depends on symptoms and the full sleep report. Do not change device settings using this result.
Understanding the result
Apnea: airflow stops
Scored respiratory pauses lasting at least 10 seconds in adults.
Hypopnea: airflow reduces
Reduced airflow with oxygen desaturation or an arousal, per scoring rules.
Scored events are divided by hours actually asleep.
Frequently asked questions
What does AHI measure?
AHI is the number of scored apnea and hypopnea events per hour of actual sleep. It describes breathing interruptions; a sleep specialist interprets the full report.
Is sleep time the same as recording time?
No. AHI uses actual sleep time. Home sleep tests may use monitoring time and report REI instead. Do not substitute time in bed for sleep time.
Can AHI diagnose OSA on its own?
No. Event type, symptoms, oxygenation and a qualified clinical assessment matter. A low AHI does not rule out other sleep disorders. Children use different criteria.
Can I use a CPAP device AHI?
Device-reported AHI is useful in follow-up, but proprietary algorithms and usage time differ from laboratory scoring. Do not treat it as a new diagnostic sleep study or adjust PAP settings from this page.
Sources & References
AASM manual for the scoring of sleep and associated events.
NHLBI resources on diagnosis and management of sleep apnea.
Adult AHI ranges and the wider clinical context.
References provide context, not endorsement. No institutional certification or review is claimed.
Calculate events per hour. Understand your sleep study.