Sleep apnea has been generally viewed as an evil that negatively affects all aspects of your life. Here at Medical Daily, we have written articles about how sleep apnea can cause greater amounts of brain damage in women, mothers' sleep apnea can cause newborns to have breathing problems, and even that the condition may increase sleepers' risk of cancer. However, there may be a silver lining to the perils of sleep apnea: for some heart attack patients, it may boost the number and ability of rare cells that can repair and build new blood vessels.

A new study looked at sleep-disordered breathing, which is characterized with apnea-induced hypoxia when the sleeper experiences a temporary drop in oxygen levels. Though somewhat rare in the general population, occurring in just 5 to 10 percent of people, it is fairly common in patients who have suffered heart attacks. In fact, 40 to 60 percent of heart attack patients suffer from sleep-disordered breathing. Sleep apnea has been linked to an increased risk of cardiovascular problems, but researchers were mystified when they realized that patients with sleep-disordered breathing tend to recover just as well as patients without it.

The researchers studied 40 patients who had suffered from heart attacks days earlier. Some had sleep-disordered breathing; others did not. Researchers drew blood samples from all of the participants and found that the patients with sleep apnea had greater numbers of endothelial progenitor cells (EPCs), which help to repair and construct new blood cells, than the healthy sleepers. Sleep-disordered patients also had higher levels of growth-enhancing proteins and immune cells that boost the production of blood vessels. In fact, researchers were able to recreate the same body effect in 12 other healthy men and women by withholding oxygen from them for short periods of time.

The finding indicated that sleep apnea may indeed stress the heart, but it may also enhance conditions for repair. Researchers noted in a statement that patients with sleep apnea "are essentially better prepared to harness the recruitment of EPCs when [a heart attack] comes knock at the door."

The study was published in the American Journal of Respiratory and Critical Care Medicine.

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