This article discusses research that shows that treating obstructive sleep apnea (OSA) may improve depressive symptoms. This has been by experience clinically and other studies have shown this. However, I have some concerns about this study. The researchers screened for depression by using a tool called the PHQ-9. It is a good tool, but some of the questions are related to fatigue and poor sleep, which can be seen in patients with untreated OSA without depression. In other words, patients with untreated OSA can seem depressed on a PHQ-9 test from the sleep disruption due to the OSA, not from depression. In this study, the patients with depression who were the most sleepy, benefited the most from treatment of their OSA. This makes me wonder again if the PHQ-9 scores were improved only because sleepiness improved, not because depression improved.