Sleep Apnea: What Do My AHI Numbers Mean?

Sleep apnea is when you stop breathing for short periods of time while you’re asleep. You might wake up often during the night to "catch your breath," but you probably won’t know it.

If your doctor thinks you might have sleep apnea, he may ask you to spend the night at a sleep center, where you’ll be hooked up to equipment that checks your heart rate, breathing patterns, brain waves, blood oxygen levels, and other vital signs while you sleep. This test is called a sleep study, or polysomnography. In some cases, your doctor might give you a device to wear at home to measure your breathing and blood oxygen levels.

“Apnea” means a complete loss of breath for 10 seconds or longer. “Hypopnea” is a partial loss of breath that lasts 10 seconds or longer. The sleep tests will tell your doctor how many times each hour you have apnea or hypopnea. Your doctor will use a scale called the apnea-hypopnea index (AHI) to tell if you have the sleep disorder and, if so, how serious it is.

What Do the Numbers on the AHI Mean?

Here's a breakdown:

  • Normal sleep: Fewer than 5 events per hour
  • Mild sleep apnea: 5 to 14 events per hour
  • Moderate sleep apnea: 15 to 29 events per hour
  • Severe sleep apnea: 30 or more events per hour

This scale is only for adults. Children are less likely to have any sleep apnea episodes, so most specialists see an AHI above 1.5 as abnormal in children. They typically need treatment if their AHI is 5 or higher.

Treatment of Sleep Apnea

If you have a moderate or severe AHI score, you might need to use a CPAP (continuous positive airway pressure) machine while you sleep. That’s a mask you wear over your nose, attached to a machine with a hose. The CPAP blows air into your nose, and that should help keep you from waking up often during the night. It also may record your AHI.

Your doctor typically will suggest lifestyle changes, too, like losing weight, exercising, quitting smoking, and sleeping on your side or stomach instead of your back. He’ll probably recommend these changes if your AHI score shows you have mild sleep apnea as well.

WebMD Medical Reference Reviewed by Melinda Ratini, DO, MS on January 30, 2018

Sources

SOURCES:

Mayo Clinic: "Sleep Apnea."

National Heart, Lung, and Blood Institute: "What is Sleep Apnea?"

American Sleep Apnea Association: "Getting a Sleep Apnea Diagnosis."

Division of Sleep Medicine, Harvard Medical School: "Apnea: Understanding the Results."

American Sleep Apnea Association: "Children's Sleep Apnea."

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