After a sleep study, you may get a report full of numbers and abbreviations. Your sleep physician will explain your results and what they mean for you, but it helps to understand the basics. Here’s a plain-English guide to the terms you’re most likely to see.
AHI: apnea-hypopnea index
The AHI is the main number used to diagnose and grade sleep apnea. It’s the average number of breathing events per hour of sleep.
- Apnea: your breathing stops or nearly stops for at least 10 seconds
- Hypopnea: your breathing becomes shallower for at least 10 seconds, usually with a drop in oxygen or a brief awakening
For adults, AHI is generally grouped like this:
- Under 5: normal
- 5 to 15: mild sleep apnea
- 15 to 30: moderate sleep apnea
- 30 or more: severe sleep apnea
RDI: respiratory disturbance index
Some reports also list an RDI. It includes apneas and hypopneas plus other, subtler breathing disruptions that disturb your sleep. It can be a little higher than your AHI.
Oxygen levels
Your report will show your oxygen saturation during the night, often including the lowest level reached and how long you spent below certain levels. Repeated drops in oxygen are one of the reasons untreated sleep apnea affects your heart and overall health.
Sleep stages and efficiency
- Sleep efficiency: the percentage of time in bed you actually spent asleep
- Sleep stages: how much time you spent in light sleep, deep sleep and REM (dreaming) sleep
- Arousals: brief awakenings, often too short to remember, that fragment your sleep
Central vs. obstructive events
Most sleep apnea is obstructive, meaning the airway is blocked. Some events are central, meaning the brain briefly doesn’t send the signal to breathe. The difference matters because treatment can differ.
Leg movements
Your report may list periodic limb movements, repeated leg movements during sleep that can be related to restless legs syndrome.
What happens next
Your numbers are just one part of the picture. Your sleep physician will consider them together with your symptoms and health history to recommend treatment, which may include PAP therapy, an oral appliance or other options. If you need CPAP, you may also be scheduled for a CPAP titration study to find the right pressure.
Book a sleep study in Deerfield Beach
Ready to get answers and better sleep? Call 1-800-481-3870 or request an appointment online. International Institute of Sleep is headquartered at 2151 W. Hillsboro Blvd., Suite 100, Deerfield Beach, FL 33442, and serves patients throughout Broward and Palm Beach counties.
This article is for general information and is not medical advice. Talk to your healthcare provider about your symptoms, and don’t stop or change a prescribed treatment without their guidance.
