LOC, ROC: Ocular channels. FZ-CZ, CZ-OZ, C4-A1: Electroencephalographic (EEG) channels. Chin, arm and Leg EMG: chin, arm and leg electromyogram channels. The leg EMG was performed on both the lower extremities on the anterior tibialis muscle, while the arm EMG was performed on the right forearm muscles. ECG: electrocardiogram. CPAP: CPAP flow channel. Sono: Sonogram channel. SpO2: oxygen saturation. SUM: summation of chest and abdominal respiratory inductance plethysmography (RIP) bands. RC and ABD: chest and abdomen RIP bands. HR: heart rate.