Sleep apnea is a potentially serious health condition that, if untreated, can contribute to high blood pressure, increased stroke risk and a number of other cardiovascular ills.

But according to a study published Wednesday in the journal Sleep and Breathing, obstructive sleep apnea may actually help protect against damage to the heart in the event of a myocardial infarction, or heart attack.

Researchers led by Neomi Shah, associate director of the Pulmonary Sleep Lab at the Montefiore Medical Center in the Bronx, N.Y., tested blood samples for people who’d been hospitalized for heart attacks. They analyzed the blood for the presence a protein called troponin-T, which is released into the bloodstream when heart muscle tissue is damaged; the more troponin-T, the greater the severity of the heart attack. They found that people with sleep apnea had low levels while the others had high levels of that telltale protein, suggesting that those with sleep apnea incurred less heart damage than those without apnea.

Obstructive sleep apnea occurs when a person’s airway is blocked or collapses when he or she is sleeping. The repeated interruption of the normal breathing pattern can deprive the body of oxygen and lead to all kinds of problems, from daytime drowsiness to obesity. In this study, 35 percent of the 136 participating patients had obstructive sleep apnea. Myocardial infarction occurs when blood flow to the heart is blocked for so long that the muscle tissue is damaged because it’s not getting enough oxygen. The study suggests that it’s possible that obstructive sleep apnea could protect against such damage by acclimating the heart muscle to oxygen deprivation ahead of time. (It’s also possible, the authors note, that people with sleep apnea and related health conditions may be quicker than others to seek medical care when suffering a heart attack.)

This study only looked at non-fatal cases of myocardial infarction, the authors note.

The authors note that their findings are in keeping with those of earlier animal studies and that they highlight the complexity of the relationship between obstructive sleep apnea and cardiovascular health.