Mild to moderate sleep apnea

Mild to moderate sleep apnea is a term used to describe all forms of obstructive sleep apnea (OSA) that are classified as less than severe. But why do clinicians sometimes lump mild and moderate sleep apnea together as one condition, instead of two separate categories?

First, let’s review the definitions of these types of sleep apnea. Sleep apnea is classified according to the apnea-hypopnea index (AHI), which is a scale that measures the severity of sleep apnea based on the collective number of “hypopneas” (periods where breathing is excessively shallow) and “apneas” (periods where breathing stops altogether) that occur during each hour of sleep.

According to the American Academy of Sleep Medicine (AASM), the AHI defines mild, moderate and severe sleep apnea as follows:

Mild sleep apnea is 5 to 15 on the AHI scale. (This means that you experience 5 to 15 periods of stopped or shallow breathing every hour that you’re trying to sleep.) The AASM lists common symptoms as “involuntary sleepiness during activities that require little attention, such as watching TV or reading.”

Moderate sleep apnea is ranked as 15 to 30 on the AHI scale, meaning 15 to 30 instances of stopped or shallow breathing per hour. Those with moderate sleep apnea commonly experience “involuntary sleepiness during activities that require some attention, such as meetings or presentations,” reports the AASM.

Severe sleep apnea is more than 30 on the AHI scale — in other words, your breathing stops (or is very shallow) more than 30 times every hour while you’re trying to sleep. According to the AASM, this causes “involuntary sleepiness during activities that require more active attention, such as talking or driving.”

Mild to moderate sleep apnea as a separate medical category

So, given these three clear degrees of sleep apnea, why do medical experts sometimes lump mild and moderate sleep apnea together? It’s basically a means of separating severe sleep apnea from the other types. Some researchers find it beneficial to pursue remedies or treatment options for mild and moderate sleep apnea that isn’t thought to be effective for severe sleep apnea.

For instance, a 2007 study from the journal Sleep and Breathing categorizes mild to moderate sleep apnea patients together in an attempt to determine the effects of ramelteon as a treatment option. A 2002 study from Laryngoscope studied the effects of radiofrequency on mild to moderate sleep apnea patients, and a 2012 study published in Respirology analyzed the characteristics of both mild and moderate sleep apnea patients.

Mild to moderate sleep apnea is also considered as something that’s separate from severe sleep apnea when it comes to prescribing treatments. Oral appliances are generally recommended for mild to moderate sleep apnea patients, and not for those with severe sleep apnea.

If you think you have symptoms of mild to moderate sleep apnea, we encourage you to speak to your doctor. We’ve looked at common mild sleep apnea symptoms in a past blog post; in our next article, we’ll explore moderate sleep apnea symptoms.