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23 Sep 2013

How Do You Determine the Severity of Sleep Apnea

This is Part 4 in series of blog posts on Sleep Apnea. Read Part 1, Part 2 & Part 3

Picture of a man snoring
Knowing the severity of sleep apnea is important when it comes to treating sleep apnea. There are three grades of sleep apnea: mild, moderate and severe.

The degree of severity is judged not only by symptoms, but also considering the obstruction to airflow and resulting reduction in oxygen level in blood (oxygen saturation)

Not all sleep experts agree on a single method to determine the severity. This is partly because there isn't much data on sleep habits and sleep apnea. This is nothing new in medicine. And as knowledge gathers, it becomes clear what is 'normal' and what is 'abnormal'. Also as we learn more about the health risks of sleep apnea, it will become possible to categorize sleep apnea based on its outcome on your health.

What is Apnea-Hypopnea Index (AHI)?

An apnea is the cessation of breathing for 10 seconds or more due to complete blockage of airway. This causes a drop oxygen saturation.

Hypopnea is partial obstruction in the airway with a reduction in airflow (by at least 30%) which results in a drop in oxygen saturation.

The AHI or apnea-hypopnea index is the number of apneas and hypopneas that occur in an hour of sleep.

What is oxygen saturation?

When blood is pumped through the lungs, it becomes saturated with oxygen. Usually this saturation is very close to 100 percent. But in sleep it can drop a little. In sleep apnea, partial or complete blockade of airways prevent gas exchange and saturation of blood oxygen.

Read the other posts in this series
Part 1 - What is sleep apnea?
Part 2 - Obstructive sleep apnea
Part 3 - Treatment options for sleep apnea


  1. HI nice Blog i have an study on your blogs and i found these very informative you share very helpful info about Symptoms Of Sleep Apnea

  2. That's a great table and very useful as I have just bought a oximeter to see if I get enough oxygen while I sleep. I have the meter but I didn't know how to interpret the reading until I saw your post.


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