It’s common to hear about the link between sleep apnea and certain physical health issues, such as diabetes and high blood pressure, but did you know that sleep apnea could also have an effect on your mental health?According to a study recently presented at an American Thoracic Society meeting, men with undiagnosed severe obstructive sleep apnea have more than double the risk of depression than men who don’t have sleep apnea. And for those who experience excessive daytime sleepiness in addition to sleep apnea, that risk of depression increases to five times greater.So, why the strong association between sleep apnea and depression? Well, researchers haven’t come to any definitive conclusions yet, reports HealthDay. University of Adelaide’s Carol Lang, one of the researchers behind this study, admitted that she can’t quite explain the association, but noted that sleep apnea and depression have common risk factors and even share similar symptoms, including fatigue, poor concentration and low vitality.Dr. Alan Manevitz, a clinical psychiatrist at Lenox Hill Hospital in New York City, pointed out that this study isn’t the first to identify the link between sleep apnea and depression."The interplay between sleep and mood has always been present,” said Manevitz. “Depression may cause sleep problems and sleep problems may cause or contribute to depression."While this new study doesn’t prove a cause-and-effect relationship between sleep apnea and depression, it does give men who suffer from either of these health issues something to think about. "Whichever diagnosis you may have, you should get screened for the other diagnosis," said Manevitz.”CPAP therapy, the gold-standard treatment for sleep apnea, has been known to reduce the risk of certain conditions linked with this sleep disorder. However, the authors of this new study noted that according to previous research, CPAP therapy doesn’t help with symptoms of depression exhibited by people with sleep apnea.Of course, CPAP compliance is still of utmost importance, as it can significantly reduce the symptoms of sleep apnea and lead to overall improved health for people who suffer from this disorder. That said, if you have sleep apnea – even if you’re undergoing treatment – you may want to keep an eye out for signs of depression.