In a large study in Europe, people with depression were found to be five times more likely to suffer from Sleep Apnea. Research has found treating Sleep Apnea with CPAP therapy may decrease symptoms of depression.
Like the chicken and the egg, no one is quite sure what causes the other. Studies have shown only an association between depression and Sleep Apnea, not the cause and effect.
It can be difficult to distinguish between the effects of Sleep Apnea and depression. According to psychiatrist Michael Weissberg, M.D., at the University of Colorado School of Medicine, "Sleep disruption, particularly insomnia, can be a risk factor for developing depression, and a lot of symptoms of people who have Sleep Apnea -- they feel lousy, they can’t think straight -- are similar to symptoms people have in depression."
In one study, nearly 800 participants with both depression symptoms and OSA were treated with CPAP therapy for at least four hours a night. Results indicated all participants who used CPAP had significant relief from depression. Even those who only partially used CPAP saw improvements.