A small study in the journal Circulation revealed that almost 60 percent of pacemaker patients also had undiagnosed sleep apnea. The researchers involved in the study posit that patients' sleep apnea could possibly contribute to their heart problems.

What is sleep apnea? Here's the Cliff Notes description: it's a sleep disorder characterized by 30 or more periods of interrupted breathing each hour during sleep. Usually, a person suffering from sleep apnea may wake-up or at least partially wake-up during these breathing interruptions. Considering the importance that sound sleep plays in cardiovascular health, it is quite clear that sleep patterns of this kind are dangerous.

As for the above mentioned study, researchers looked at 98 British, French and Belgian pacemaker patients and noted that thirty-six of of them had sinus node disease, in which a heart chamber pumps too slow or too fast. Furthering the connection, it is known that abnormally slow heart rhythms (known as Bradycardic rhythm disorders) are common among patients with obstructive sleep apnea. The tricky part is that the researchers could not determine if the sleep apnea came before the pacemaker, or if it developed after the pacemaker therapy began.