There are several obstructive sleep apnea (OSA) side effects your doctor may ask you about at your next visit—daytime fatigue, snoring, and waking up with dry mouth—but there's another OSA side effect no one might be bringing up that could seriously be impacting your personal life. We're talking about erectile dysfunction (ED). OSA is among the least studied risk factor in erectile dysfunction. So even if you went to your doctor with an ED problem in the first place, they might not have even mentioned sleep apnea. They're probably more likely to ask about your stress levels and how that could impact your sex life. And on the other side of the equation, your sleep doctor may have heard of the associations between OSA and a man's sexual function, but if he or she doesn't mention it, you might not think there's a correlation. But, this side effect is just as important to get resolved as all of the other serious health risks you might be facing with OSA. As OSA is studied more and found in ED patients, researchers are discovering that when OSA is managed with CPAP treatment, it can help with ED. A 2009 study out of Germany found that OSA was diagnosed in over 90 percent of the study subjects that had ED. Those researchers suspected the sexual function issue was due to the low levels of oxygen in the blood caused by the effects of sleep apnea. A 2018 study of ED prevalence in male patients with OSA in the 18 to 70-year-old age range found that 51 percent of the patients diagnosed with OSA were experiencing erectile dysfunction. The good news is, the researchers evaluated how three months of CPAP treatments impacted the men's sexual function, as well as their sexual satisfaction and psychological profiles. There were significant increases in erectile function, sexual satisfaction, and the man's reported overall satisfaction after getting CPAP treatment. So what does one's OSA and breathing at night have to do with their sexual function? It may have to do with not having enough oxygen in the blood, as the earlier study mentioned, which can impact sexual function. It's also a problem with testosterone. In the 2018 study, the men who had ED issues had lower testosterone levels. During Rapid Eyes Movements (REM) sleep, testosterone levels peak. When a man isn't getting that important REM sleep because he's dealing with splintered sleep and inadequate oxygen due to OSA, his testosterone levels dip, which could result in erectile dysfunction if not resolved, suggests that recent study. The men who received CPAP treatment saw small increases in their testosterone levels at the three-month follow up. It's important to remember that sleep-disordered breathing impacts the whole body, in particular, the vascular systems and hormones that regulate the body's sexual function. With CPAP treatment offering promising results for OSA treatment, ask your physician if OSA could be a factor with this sexual function issue.