What is severe sleep apnea and how do you treat it? (2025)

Severe sleep apnea might seem like a redundant phrase to many of us. After all, it’s hard to think of any condition that prevents you from sleeping — costing you energy and wakefulness during the day and connected to a host of other serious diseases likeheart failure andstroke— as anything other than “severe.”

But, as with most other health conditions, there are varying degrees of severity when it comes to sleep apnea. And we’re learning that more severe sleep apnea is strongly associated with more extreme health risks. So, with that in mind, what is generally considered to be severe sleep apnea, and what risks does severe apnea present to your health in general?

The apnea–hypopnea index (AHI) determines severe obstructive sleep apnea (OSA) by measuring the number of apneas (stopped breathing) and/or hypopneas (constricted breathing) that you experience during each hour of sleep, usually measured as part of a sleep study.

So, if you experience from five to 15 apneas and/or hypopneas per hour, your sleep apnea would be considered mild, according to this index. Moderate OSA is considered 15 to 30 apneas and/or hypopneas per hour of sleep, and 30 or more is classified as severe obstructive sleep apnea.

Why is it important to know if your OSA is considered severe apnea? As you can probably guess, severe sleep apnea presents greater risks to your health. Common comorbidities such asdiabetesandheart diseaseare connected to severe apnea. But more alarmingly, some recent studies have shown that people with severe obstructive sleep apnea may be at much greater risk for fatal events such as cancer.

Specifically, severe sleep apnea sufferers may be five times more likely to die of cancer according to research published last year. A study focusing on about 1,500 government workers in Wisconsin over a period beginning in 1989 “showed that those with the most breathing abnormalities at night had five times the rate of dying from cancer as people without the sleep disorder,”reportedThe New York Times.¹

Another study of thousands of sleep patients in Spain “found that those with the most severe forms of sleep apnea had a 65 percent greater risk of developing cancer of any kind.” TheTimesarticle specified that both studies looked at general and not specific cancer diagnoses and outcomes, and both came to their conclusions after taking into consideration the “usual risk factors for cancer, like age, smoking, alcohol use, physical activity and weight.”

Even so, findings showed that “people with moderate apnea were found to die of cancer at a rate double that of people without disordered breathing at night, while those in the severe category died at a rate 4.8 times that of those without the sleep disorder.”

That study supports earlier findings that severe sleep apnea increased the risk of death. In 2009, a studypublished byPLOS Medicinefollowed 6,441 men and women with and without sleep apnea “to see if there was any correlation between apnea and a higher risk of death,” asScientific Americanreportedat the time. ^2,3

During the 15 years of the research, 1,047 of the subjects passed away. “After adjusting for age, race, body mass index (BMI) and smoking, the authors found that men ages 40 to 70 with severe apnea … had about one and a half times higher risk of dying from any cause than those who did not.”

Of course, these are studies, and not conclusive proof. But they do reinforce long-standing beliefs about the dangers of severe obstructive sleep apnea, and they underline the danger of having that condition go untreated.

“This is really big news,” Dr. Joseph Golish, a Cleveland-based professor of sleep medicine, said in the Times article. “Until disproven, it would be one more reason to get your apnea treated or to get it diagnosed if you think you might have it.”

This blog post contains general information about medical conditions and potential treatments. It is not medical advice. If you have any medical questions, please consult your doctor.

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