Understanding Severe Sleep Apnea

Understanding Severe Sleep Apnea

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 like  heart failure  and  stroke — 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 as diabetes and  heart disease  are 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,” reported The 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.” The Times article 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 study published by PLOS Medicine followed 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,” as Scientific American reported at 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.”



  1. O’Connor, Anahad. 2012. Sleep apnea tied to increased cancer risk. New York Times, May 20, 2012. http://well.blogs.nytimes.com/2012/05/20/sleep-apnea-tied-to-increased-cancer-risk/ (accessed July 1, 2013).
  2. Punjabi NM, Caffo BS, Goodwin JL, Gottlieb DJ, Newman AB, et al. 2009. Sleep-Disordered Breathing and Mortality: A Prospective Cohort Study. PLoS Med 6(8): e1000132. doi:10.1371/journal.pmed.1000132. http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000132 (accessed July 1, 2013).
  3. Harmon, Katherine. 2009. Severe sleep apnea may bring greater risk of death for some. Scientific American, August 18, 2009. http://www.scientificamerican.com/article.cfm?id=sleep-apnea-death (accessed July 1, 2013).


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