We know recurrent episodes of apnea, over months and years, may cause an increase in carbon dioxide levels that can change the pH of the blood enough to cause a respiratory acidosis. We also know sleep apnea may be prevalent in patients with bipolar I disorder. It would be great to see a comparison study of patients with OSA versus CSA (specifically REM-related sleep apnea) examining acidosis, mood disorder prevelence, and outcomes in treated versus untreated populations.