People suffering from sleep apnea are three to four times more likely to die prematurely, according to the results of a study published in the August 1 issue of the journal Sleep.

Obstructive sleep apnea (OSA) is caused by a blockage of the airway, usually when the soft tissue in the rear of the throat collapses and closes during sleep. Actually, the Greek world “apnea” literally means “without.”

According to the National Institutes of Health, sleep apnea is very common, affecting more than twelve million Americans. Risk factors include being male, overweight and over the age of forty, but sleep apnea can strike anyone at any age, even children. Worrisome is the fact that around 80 percent of men and 93 percent of women with sleep apnea are unaware they have this disorder, despite the fact that it can have significant consequences.

Untreated, sleep apnea can cause high blood pressure and other cardiovascular disease, memory problems, weight gain, impotency, and headaches.

Now a new study shows that sleep apnea puts people at risk of death as well. For the study, researcher Nathaniel Marshall, a postdoctoral fellow at the Woolcock Institute of Medical research in Sydney and colleagues followed 1522 generally healthy men and women who participated in the Wisconsin Sleep Cohort study for about 13.8 years. The participants were tested for sleep-disordered breathing at the beginning of the study. Those diagnosed with sleep apnea were divided into groups according to the severity of their condition.

The researchers found that about 19 percent of those with severe sleep apnea died during the follow-up period compared with only 4 percent of those without the condition. The risk of death rose along with the severity of the condition. The risk of death was also increased in people who did no treat their sleep apnea.

What put people with sleep apnea more at risk? The researchers found a strong link between sleep apnea and heart-related disease. More exactly, about 42 percent of deaths in the group of people with severe sleep apnea were due to heart disease. Moreover, the risk of heart-related death was more than five times higher among those with untreated severe sleep apnea compared with those without sleep apnea.

“Our findings ... remove any reasonable doubt that sleep apnea is a fatal disease. People who have, or suspect that they have, sleep apnea should consult their physicians about diagnosis and treatment options,” Marshall said.

The study was supported by the National, Heart and Blood Institute of the National Institutes of Health.