Making Sense of Your Sleep Study Report
After your sleep study, you'll receive a detailed report with numbers, measurements, and medical terminology that can feel overwhelming. The most important number in your report is your Apnea-Hypopnea Index (AHI). Understanding this number is key to understanding your diagnosis and treatment plan.
What Is AHI?
The Apnea-Hypopnea Index measures how many times per hour your breathing is disrupted during sleep:
- Apnea — A complete pause in breathing lasting at least 10 seconds
- Hypopnea — A partial reduction in airflow (at least 30%) lasting at least 10 seconds, associated with an oxygen drop or arousal
Your AHI is calculated by dividing the total number of apneas and hypopneas by the total hours of sleep.
AHI Severity Classification
- Normal: AHI less than 5 — No significant sleep apnea
- Mild: AHI 5-14 — Some breathing disruptions; treatment may be recommended based on symptoms
- Moderate: AHI 15-29 — Treatment is generally recommended
- Severe: AHI 30+ — Treatment is strongly recommended
Other Important Numbers in Your Report
- Oxygen nadir — The lowest blood oxygen level recorded during sleep. Levels below 90% are concerning; below 80% is severe.
- Oxygen desaturation index (ODI) — How many times per hour oxygen drops by 3-4%
- Sleep efficiency — Percentage of time in bed actually spent sleeping (normal is above 85%)
- REM AHI — AHI specifically during REM sleep, which is often worse
- Supine AHI — AHI when sleeping on your back, often higher than side sleeping
- Arousal index — Number of brief awakenings per hour
- PLM index — Periodic leg movements per hour
How AHI Guides Treatment
Your AHI, combined with your symptoms and overall health, determines the treatment approach:
- Mild OSA (AHI 5-14) — May be treated with lifestyle changes, positional therapy, or an oral appliance. CPAP may be recommended if symptoms are significant.
- Moderate OSA (AHI 15-29) — CPAP is typically the first-line treatment. Oral appliances are an alternative option.
- Severe OSA (AHI 30+) — CPAP or BiPAP is strongly recommended. Inspire therapy may be an option for patients who can't tolerate PAP.
Myth vs. Fact
Myth: A low AHI means I don't need treatment.
Fact: Even mild sleep apnea (AHI 5-14) may warrant treatment if you have significant symptoms like daytime sleepiness, morning headaches, or cardiovascular risk factors.
Key Takeaways
- AHI measures the number of breathing disruptions per hour of sleep
- Severity ranges from mild (5-14) to severe (30+)
- Oxygen levels, sleep efficiency, and position data are also important
- Treatment decisions are based on AHI combined with symptoms and health risks
- Your sleep specialist will explain your results and recommend a personalized plan
