Hospital and clinic documents
Sleep study (polysomnography) report explainer
A sleep study turns one night into pages of indices: events per hour, oxygen dips per hour, minutes in each stage of sleep. The abbreviations (AHI, RDI, ODI, WASO, REM) are seldom spelled out. Add your report below to see each one named, with a note on what it counts.
Explain your sleep study (polysomnography) report
- 1. Add itDrop a PDF, take a photo or paste the text.
- 2. Check itPersonal details are removed on your device. You approve what is sent.
- 3. Read itSummary, table of results, terms and questions to ask.
The explainer opens on its own page with no adverts and no outside scripts. Your file is read on your device and is never uploaded.
What you get
- Sleep time, sleep efficiency and the minutes or percentage spent in each stage, in one table.
- Breathing events separated into apneas and hypopneas, with the index your report calculates.
- Oxygen figures such as ODI, lowest SpO2 and time below a stated level explained.
- The severity wording and recommendations from the summary, quoted as written.
Lines you will usually see on a sleep study report
- Total sleep time (TST) and sleep efficiencyHow long you slept, and that time as a share of the time in bed
- Sleep stages N1, N2, N3 and REMLighter sleep, deep sleep and dreaming sleep, each as minutes or a percentage
- Apnea and hypopneaA pause in breathing, and a spell of shallow breathing
- AHIApnea-hypopnea index, the average number of those events per hour of sleep
- Obstructive, central and mixedWhether breathing effort continued during an event, stopped, or did both
- ODIOxygen desaturation index, the number of times per hour the blood oxygen level dipped by a set amount
- Lowest SpO2 (nadir) and arousal indexThe lowest oxygen reading of the night, and the number of brief awakenings per hour
What this tool cannot tell you
One night in a sleep laboratory or with a home kit may not match a usual night, and home studies that do not record sleep itself count events per hour of recording instead. The rules for scoring a hypopnea also differ between laboratories, which changes the index. MedicDecode names each figure and repeats the severity grade your report gives without applying a grade of its own. Whether the result calls for treatment is a decision for your sleep physician.
Common questions
What is the difference between AHI, RDI and REI?
All three count breathing events per hour. AHI counts apneas and hypopneas per hour of sleep, RDI may add other breathing-related arousals, and REI is used by home tests that measure recording time instead of sleep.
Why are supine and REM figures listed separately?
Breathing events can vary with body position and sleep stage, so reports break the index down for time on your back and for REM sleep. This shows the reader where in the night the events were counted.
My study was done at home. Is the report different?
Home studies record breathing, oxygen and heart rate, and most do not record brain waves. There are then usually no sleep stages on the report, and the index is worked out against recording or monitoring time.
Words you may see on this report
Tap a word for its plain-English meaning, an example line and what it does not mean.
- Dialysis
Dialysis is a treatment that removes waste and extra fluid from the blood when the kidneys can no longer do this well enough.
- Directly observed therapy
Directly observed therapy (DOT) means a health worker watches you take each dose of a medicine, most often for tuberculosis treatment.
- Discharge summary
A discharge summary is a document written when you leave hospital that explains why you were there, what was done, and what happens next.
- Follow-up appointment
A follow-up appointment is a planned visit after a test, treatment or hospital stay to check progress and decide next steps.
- Hemodialysis
Hemodialysis is a treatment where a machine filters the blood to remove waste and extra fluid when the kidneys cannot do it well enough.
- Nil by mouth
Nil by mouth means a person should not eat or drink anything, usually before surgery, a procedure or certain tests.
- Palliative
Palliative means care or treatment focused on easing symptoms and improving quality of life, rather than on removing the illness itself.
- Referral
A referral is when one health professional asks another, usually a specialist or service, to see you or carry out a test.
- Triage
Triage is the process of sorting patients by how urgently they need care, so the most urgent are seen first.
- Vital signs
Vital signs are basic body measurements, such as heart rate, blood pressure, breathing rate, temperature and oxygen level.