How-to guide
How to Read Your Sleep Study Results
Quick answer: The apnea-hypopnea index (AHI) is the average number of times an hour your breathing stops or becomes very shallow while you sleep. For adults, an AHI under 5 is normal, 5 to 14 is mild sleep apnea, 15 to 29 is moderate and 30 or more is severe. The lowest oxygen level (oxygen nadir) shows how far your oxygen dropped during those pauses; below 90% is low. We use these numbers, your symptoms and your health to choose treatment, such as CPAP, an oral appliance, Inspire, nasal surgery or weight loss.
What is the AHI?
The apnea-hypopnea index (AHI) counts how many times an hour, on average, your breathing stops (an apnea) or becomes very shallow (a hypopnea) while you are asleep. It is the main number used to tell whether you have sleep apnea and how severe it is.
| AHI (events per hour) | What it means for adults |
|---|---|
| Under 5 | Within normal limits |
| 5 to 14 | Mild sleep apnea |
| 15 to 29 | Moderate sleep apnea |
| 30 or more | Severe sleep apnea |
A home sleep test does not measure sleep itself, so its report may call this number the REI (respiratory event index) or pAHI. It is read the same way.
Children use different, lower limits, so a child’s results are read differently.
What is the lowest oxygen level?
The lowest oxygen level, or oxygen nadir, is the lowest point your blood oxygen reached while you slept. Awake, most healthy people have an oxygen level of 95% or higher. It can dip a little during normal sleep, but levels below 90% are considered low.
Drops in oxygen happen during breathing pauses. Repeated or deep drops strain the heart and blood vessels over time, which is one reason treatment matters.
What else is on my report?
- Oxygen desaturation index (ODI): how many times an hour your oxygen dropped by a set amount, usually 3% or 4%.
- Time below 90% (often shown as T90): how long your oxygen stayed under 90% during the night.
- Respiratory disturbance index (RDI): like the AHI, but it also counts smaller breathing disruptions that wake the brain briefly, so it is often a little higher than the AHI.
- Sleep position: how much of the night you spent on your back or side. If your apnea is much worse on your back, sleeping on your side may help.
- Snoring and sleep time: how loud and how often you snored, and about how long you slept.
What do my results mean for me?
Sleep apnea can cause loud snoring, waking up unrefreshed, morning headaches, and feeling tired, irritable or foggy during the day. Over time, untreated sleep apnea is linked to high blood pressure, heart disease, stroke, diabetes and drowsy-driving crashes.
Treatment is recommended for moderate or severe sleep apnea, and for mild sleep apnea when it causes symptoms such as daytime sleepiness or comes with high blood pressure. We look at your numbers together with your symptoms and health when we recommend a treatment.
What are my treatment options?
- CPAP: a machine that gently blows air through a mask to keep your airway open. It works for mild to severe sleep apnea. See How to Get Started With CPAP.
- Oral appliance: a custom mouthpiece that holds your lower jaw forward, made by a dental sleep specialist we refer you to. Often used for mild to moderate sleep apnea.
- Inspire: an implant that keeps the airway open during sleep, for adults with moderate to severe sleep apnea who cannot use CPAP. Weight and other measurements decide who qualifies. See Inspire.
- Nasal treatment: treating a blocked nose, such as a deviated septum, large turbinates or sinus problems, can make breathing and CPAP easier. See nasal surgery and sleep apnea.
- Weight loss: losing weight can lower the AHI. Tirzepatide (Zepbound) is approved for adults with obesity and moderate to severe sleep apnea. See GLP-1 medicines and sleep apnea.
- Sleep position and habits: sleeping on your side, and avoiding alcohol and sedating medicines in the hours before bed.
Other options, including surgery on the throat for some people, are covered on our CPAP alternatives page.
What happens next?
At your follow-up visit, we go over your results and decide on a treatment plan together. Bring your questions, and tell us about any trouble with daytime sleepiness, especially while driving.
When should I call?
Call us for
- You have not been scheduled to go over your results
- You have questions about your results or treatment options
- You feel very sleepy during the day, or nearly fall asleep while driving. Do not drive while you feel that sleepy.
Call 911 or go to the ER for
Chest pain or trouble breathing.
Austin 512-339-4040 · Lakeway 512-682-4798 · Marble Falls 830-992-2830
Questions patients ask
For adults, an AHI under 5 events an hour is within normal limits. 5 to 14 is mild sleep apnea, 15 to 29 is moderate and 30 or more is severe.
It is the lowest blood oxygen level reached during sleep. Awake, most healthy people are at 95% or higher; levels below 90% during sleep are considered low.
Treatment is recommended for mild sleep apnea when it causes symptoms such as daytime sleepiness or comes with high blood pressure. Moderate and severe sleep apnea are treated.
CPAP, an oral appliance from a dental sleep specialist, Inspire, treating a blocked nose, weight loss including medicines such as Zepbound, and sleeping on your side.
This guide is for educational purposes only and does not replace an in-person evaluation. If we gave you different instructions, follow ours.
Full guide: capitalent.com/sleep-study-results.html
Sources
- Kapur VK, Auckley DH, Chowdhuri S, et al. Clinical practice guideline for diagnostic testing for adult obstructive sleep apnea. J Clin Sleep Med. 2017. PubMed
- Patil SP, Ayappa IA, Caples SM, et al. Treatment of adult obstructive sleep apnea with positive airway pressure: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med. 2019. PubMed
- Malhotra A, Grunstein RR, Fietze I, et al. Tirzepatide for the treatment of obstructive sleep apnea and obesity. N Engl J Med. 2024. PubMed