AHI Sleep Study Results: How to Read Your Report
What the AHI on a home test or sleep lab report counts, how guidelines grade it, what else the report shows and why one number does not decide therapy.
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Your home sleep test or sleep lab night is over. The report is full of abbreviations: AHI, ODI, SpO2, supine. Often you see the number before anyone explains it. Keep the report in a folder or as a PDF in Sam's Health Vault, your own copy apart from any patient record.
This guide covers what the AHI counts, how guidelines grade it and what else the report shows. What to write down before the test is in Sleep Apnea: What to Log for Your Sleep Doctor. How snoring differs from sleep apnea is explained in Sleep Apnea vs Snoring: What Sets Them Apart. What Sam keeps for sleep apnea, such as symptoms in the symptom diary, is on the sleep apnea page. None of it replaces going through the results with your doctor.
What does the AHI actually count?
AHI stands for apnea-hypopnea index. An apnea is a breathing pause that lasts longer than ten seconds, according to InformedHealth.org. A hypopnea is a stretch of shallow breathing. The S3 guideline of the German Sleep Society (DGSM) defines the AHI as apneas plus hypopneas per hour of sleep.
A made-up example: 120 apneas and hypopneas over six hours of sleep give an AHI of 20 per hour.
What the hour refers to matters. In a sleep lab, brainwave recording (EEG) shows when you are actually asleep. A home test has no EEG. It divides by the time it was recording, awake time included. The American Academy of Sleep Medicine (AASM) says this can underestimate the true AHI. It calls the home-test figure the respiratory event index (REI). The German guideline adds that a home test grades severity less precisely.
If your report shows an RDI, it also counts brief arousals caused by breathing effort, according to the AASM. Those can only be scored with an EEG.
How is the AHI graded?
The cut-offs differ by a point or so between sources. Here are three side by side, all per hour:
| Band | AASM guideline 2009 | NHS | German S3 guideline, 2017 short version |
|---|---|---|---|
| mild | 5 to under 15 | 5 to 14 | no band of its own (therapy chapter: mild up to 15) |
| moderate | 15 to 30 | 15 to 30 | over 15 to under 30 |
| severe | over 30 | over 30 | over 30 |
The AASM sets its bands for the RDI. At exactly 15 or 30, the sources do not agree.
Whether you have obstructive sleep apnea at all follows the International Classification of Sleep Disorders (ICSD-3). The AASM sums it up: 5 or more with typical symptoms, or 15 or more even without them. The German guideline puts the second threshold at more than 15, so the sources differ at exactly 15. Typical symptoms include daytime sleepiness, unrefreshing sleep, fatigue, insomnia, waking up gasping or choking, loud snoring and witnessed pauses. The German guideline also counts relevant other conditions. It requires that nothing else, such as a medicine, explains the breathing problem.
These are criteria for doctors, not a test to run on your own report. None of the sources defines a "normal" AHI. Below 5 meets none of the definitions. That is no all-clear if symptoms continue: a home test cannot reliably rule out sleep apnea, says the German guideline. The AASM recommends a sleep lab study when a home test is negative, inconclusive or technically inadequate. Whether that applies to you is your sleep doctor's call.
What else is on a sleep study report?
The German guideline lists the usual home test channels: airflow, breathing effort, blood oxygen, pulse and body position. A sleep lab also records your brainwaves and your eye and leg movements, with a video camera, says InformedHealth.org. That gives the report more lines:
- Recording time or sleep time: the hours the AHI is based on.
- Obstructive and central apneas: in the obstructive kind the upper airway collapses. In the central kind there is no breathing effort, per the German guideline.
- ODI, the oxygen desaturation index: how often per hour blood oxygen briefly dips. A Sleep Research Society task force says the report should state whether it counts dips of 3 or 4 percent.
- Oxygen figures such as the average, the lowest reading or the share of time below 90 percent (T90).
- AHI by body position: at least twice as high on your back usually counts as supine-dependent sleep apnea, per the German guideline.
- From a sleep lab, also sleep stages, broken sleep and arousals.
- A note on scoring: the German guideline wants trained staff to score the recording by eye. It does not recommend automatic scoring alone.
None of the sources cited here grades the oxygen figures the way it grades the AHI. What they mean for you is for your doctor to explain. How far a watch's blood oxygen reading goes is covered in Apple Watch blood oxygen: normal range and accuracy.
How do you read a report with real numbers?
A made-up extract from a home test, not a real person:
| Line on the report | Value |
|---|---|
| Recording time | 7 h 05 min |
| AHI | 18 per hour |
| of which obstructive apneas, central apneas, hypopneas | 9, 1 and 8 per hour |
| AHI on your back, in other positions | 34 and 9 per hour |
| Time on your back | 38 percent |
| ODI (3 percent dips) | 16 per hour |
| Blood oxygen average, lowest | 93 and 83 percent |
| Time below 90 percent (T90) | 4 percent |
| Scored by eye | yes |
Because a home test divides by recording time, the figure per hour of sleep could be higher. On the back, the AHI is more than twice as high. The German guideline calls that pattern supine-dependent. The sources give no bands for the oxygen figures.
The numbers are invented and not a benchmark. Your sleep doctor judges whether sleep apnea is present, how marked it is and what follows. Your symptoms and other conditions are part of that. A result that looks harmless is no reason to put off an appointment.
Why is the AHI not the whole story?
The German guideline says the AHI sets severity together with your symptoms and other conditions. There are reasons for that:
- Scoring rules: one rule counts a hypopnea with a 3 percent oxygen dip or an arousal. Another needs a 4 percent dip. Depending on the rule, the AHI can differ considerably in the same person, says the AASM.
- Variation: the figure changes from night to night. The Sleep Research Society task force lists this as one source of measurement error.
- Symptoms: the same task force says the AHI explains little of how strong symptoms are. In population studies, fewer than half of people with moderate to severe sleep apnea reported excessive sleepiness.
- Heart and circulation: per a 2025 DGSM position paper, the AHI does not capture cardiovascular risk well. Measures such as hypoxic burden, how deep and how long oxygen dips, suit that better.
In 2023, the German Sleep Society said that doctors treat individual people with their symptoms and risks, not AHI figures. The AASM's 2009 guideline wants options discussed with severity, risk factors, other conditions and your expectations in mind. It also says you should take an active part in the decision on the type of therapy.
What can you ask about your report?
Write your questions down before the results appointment. For example:
- Which index is it, AHI, RDI or REI, and per hour of sleep or of recording?
- Which rule was used to count hypopneas?
- How many hours could be scored?
- Were there central apneas, and what does that mean for me?
- How does the AHI on my back compare with other positions?
- What do the oxygen figures mean for me?
- Is the home test enough, or would a sleep lab study help?
Bring your symptom notes too, such as sleepy days and what a bed partner saw at night. What belongs in them is in our guide on what to log for your sleep doctor.
Are Apple Watch breathing disturbances an AHI?
No. Apple says the watch uses its accelerometer to look for breathing disturbances while you sleep. It rates them "Elevated" or "Not Elevated". Apple's page on the feature does not describe an AHI. A home test records airflow, breathing effort and blood oxygen, and a doctor reviews it.
Apple says its sleep apnea notifications are not intended to diagnose. Not all people with sleep apnea receive one, it adds. What to do after a notification is in our post on the sleep apnea notification. Sam does not read Apple's breathing disturbances or notifications from Apple Health and does not show them.
What does Sam do with a sleep study report?
Sam keeps the report as a document. You scan it, pick photos or import a PDF into the Health Vault. The app shows how many documents you can store. Text recognition runs on your iPhone. Once you consent, the recognized text is sent to an AI model on EU servers. It writes a recap of at most two sentences and lists details as they are printed. The rule it follows is to restate what the document says and interpret nothing. You can edit both. Check them against the original. Sam hosts health data in the EU; which service providers are involved is listed on the sub-processors page.
Sam has no field for the AHI and does not calculate it. If your report prints the AHI, it can appear in the recap or the list of details as text, exactly as printed. That is a line from your report, not Sam's measurement. If your report names a severity or a recommendation, that can appear there too. It comes from the report, not from Sam. The Health Vault knows about 33 lab values from blood tests by name. Sleep study figures are not among them. So there is no AHI trend, no grading by Sam and no comparison of two sleep reports. The comparison of your last two reports covers blood tests only. When you save the report, check that its type is not set to Blood panel. Sam reads only a blood panel as a table of values. The AHI would then appear there as a value with its printed range.
You can ask Sam Chat questions about the document. Sam Chat repeats what the document says. What a value means for your health is for your doctor to say. The recap and the answers are not medical advice.
Sam does not count breathing pauses and makes no diagnosis. Sleep duration and sleep stages from Apple Health and your symptoms in the symptom diary are in the same app.
When should you not wait for the results appointment?
If you get drowsy or nod off while driving, pull over, stop driving and do not drive again until a doctor has looked into the sleepiness. Book that appointment now and do not wait for the results appointment: InformedHealth.org notes that dozing off at the wheel can be dangerous. The same applies if you are so sleepy during the day that you could nod off at the wheel. Repeatedly witnessed breathing pauses and sleepiness that limits your day are also reasons to see a doctor soon. If symptoms get worse, contact your doctor earlier.
For sudden severe shortness of breath or chest pain, call your local emergency number (112 in the EU, 999 in the UK, 911 in the US). Do not wait for it to pass.
Keep your sleep study report in Sam and bring it to the appointment
At the appointment, your report and your symptoms are in one app, not in a stack of paper.
- Instead of a folder in a drawer: the report sits in the Health Vault as a photo or PDF. You open the original in the exam room.
- Instead of copying it out: once you consent, Sam lists the report's details as printed. You check them against the original.
- Instead of memory: you log daytime sleepiness, snoring or headaches per day in the symptom diary.
- Instead of screenshots: sleep duration and sleep stages from Apple Health are in the same app, a few taps away.
Sam does not store the AHI from a sleep report as a value, does not grade it itself and does not interpret it. The recap and Sam Chat are not medical advice. More on the sleep apnea page.
Try Sam for freeSam is a wellness companion, not a medical device. The app does not diagnose, treat, cure or prevent any condition or health state. Always consult qualified professionals for medical decisions.
Related reading
- Sleep Apnea: What to Log for Your Sleep Doctor
- Sleep Apnea vs Snoring: What Sets Them Apart
- Apple Watch sleep apnea notification: what to do
- Apple Watch blood oxygen: normal range and accuracy
- Apple Watch sleep stages vs. polysomnography: how accurate?
Sources
Updated: October 2026
- AASM, Epstein LJ et al.: Clinical Guideline for the Evaluation, Management and Long-term Care of Obstructive Sleep Apnea in Adults, J Clin Sleep Med 2009
- AASM, Kapur VK et al.: Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea, J Clin Sleep Med 2017
- Sleep Research Society task force, Malhotra A et al.: Metrics of sleep apnea severity: beyond the apnea-hypopnea index, Sleep 2021
- NHS: Sleep apnoea (last reviewed 11 May 2026)
- InformedHealth.org (IQWiG): Obstructive sleep apnea (updated 25 August 2026)
- German Sleep Society (DGSM): S3 guideline on sleep-related breathing disorders in adults, short version (PDF) (2017, in German)
- German Sleep Society (DGSM): Partial update of the S3 guideline, AWMF 063-001 (PDF) (2020, in German; under revision according to a DGSM statement of October 2023; we could not open the AWMF register to confirm its current status)
- German Sleep Society (DGSM): Statement on the AHRQ review of positive airway pressure therapy (PDF) (5 October 2023, in German)
- Nilius G et al.: Position paper of the DGSM on polysomnography (PDF), Somnologie 2025 (in German)
- Apple Support: Sleep apnea notifications on your Apple Watch (published 14 September 2026)
More on Sleep Apnea
Frequently Asked Questions
What is a normal AHI?+
None of the guidelines defines a normal AHI. They define when sleep apnea is present: an index of 5 or more per hour with typical symptoms or other relevant conditions, or more than 15 even without (the AASM, citing the international classification, says 15 or more). A result under 5 is no all-clear if symptoms continue, because a home test cannot reliably rule sleep apnea out. Your sleep doctor reads it with your symptoms.
What AHI counts as mild, moderate or severe sleep apnea?+
The AASM's 2009 guideline grades 5 to under 15 as mild, 15 to 30 as moderate and over 30 as severe. The NHS uses 5 to 14, 15 to 30 and over 30. The German S3 guideline (2017 short version) calls over 15 to under 30 moderate and over 30 severe; it sets no mild band there, but its therapy chapter calls an AHI up to 15 mild. These bands are for doctors, not a test to run on yourself.
What is the difference between AHI, RDI, REI and ODI?+
The AHI counts apneas and hypopneas per hour of sleep. The RDI also counts brief arousals caused by breathing effort, which needs brainwave recording. The REI is the AASM's term for the same count from a home test, per hour of recording. The ODI counts how often per hour blood oxygen dips, and the report should say whether it counts dips of 3 or 4 percent.
Why can a home sleep test show a lower AHI than a sleep lab?+
A home test records no brainwaves, so it cannot tell when you were asleep. It divides by the whole recording time, awake time included, which the AASM says can underestimate the true AHI. The German guideline adds that a home test grades severity less precisely.
Does the AHI alone decide on therapy?+
No. The German guideline says the AHI sets severity together with your symptoms and other conditions. A 2023 statement from the German Sleep Society says doctors treat individual people with their symptoms and risks, not AHI figures. What fits you is something to discuss with your sleep doctor.
Are Apple Watch breathing disturbances the same as an AHI?+
No. Apple says the watch uses its accelerometer to look for breathing disturbances and rates them Elevated or Not Elevated; Apple's page does not describe an AHI. Apple also says its sleep apnea notifications are not intended to diagnose. Sam reads neither the breathing disturbances nor the notifications from Apple Health.
Can Sam read the AHI from my sleep study report?+
Only as a line of text. Sam has no field for the AHI and does not calculate it. Once you consent, an AI model on EU servers writes a short recap and lists details as they are printed, without interpreting them. If the AHI is printed in your report, it can appear there as a line of text. Sam does not store it as a value as long as the report is not filed as a blood panel, and it has no grade of its own and no trend for it. The recap and Sam Chat are not medical advice. Always check the details against the original report.
Do I have to wait for my results appointment?+
Not in these cases. If you get drowsy or nod off while driving, pull over, stop driving and do not drive again until a doctor has looked into the sleepiness. Book that appointment now. The same applies if you are so sleepy during the day that you could nod off at the wheel. Repeatedly witnessed breathing pauses and sleepiness that limits your day are also reasons to see a doctor soon. For sudden severe shortness of breath or chest pain, call your local emergency number (112 in the EU, 999 in the UK, 911 in the US) and do not wait for it to pass. If symptoms get worse, contact your doctor earlier.