A 43-year-old man was referred to our tertiary sleep center for the initiation of sleep apnea treatment. A prior diagnostic overnight polysomnography (Fig 1) had revealed an apnea-hypopnea index (AHI) of 22/h of sleep. The apneas were predominantly central (central AHI, 18.2/h; obstructive AHI, 3.8/h), more pronounced in the supine position (AHI supine, 36.6/h; AHI nonsupine, 11/h) and during non-rapid eye movement (non-REM) sleep (REM, 15.8/h; non-REM, 23.5/h). A continuous positive airway pressure (CPAP) trial in an outpatient setting had failed, as the fixed CPAP of 11 cm H2O was not tolerated by the patient because of a feeling of lightheadedness when wearing the mask. At referral, the patient complained about falling asleep in front of the computer in the afternoons despite regular bedtimes and 7 to 8 h of sleep per night. His Epworth Sleepiness Scale score was 11. He had no significant past history including cardiopulmonary disease. He was not taking any medication but had noticed a slow decline in general physical performance in the last year, with dyspnea (New York Heart Association class I) after running distances of 1 to 2 km. He had never experienced syncope. His family history was unremarkable.