Fig. 1. Polysomnograph record from an obese obstructive sleep apnea patient (48-yr-old man, body mass index = 41.5 kg/m2, apnea–hypopnea index = 123 h−1). The patient is in non–rapid eye movement sleep stage. Typical repetitive pattern of obstructive apnea, desaturation, and cortical arousal with reestablishment of airflow is seen. Airflow = nasal pressure recording of airflow; chest wall = movement of chest wall; ECG = electrocardiogram; EEG = electroencephalogram; EMG = submental electromyogram; EOG = electro-occulogram; Spo2= percutaneous arterial oxygen saturation.