Polysomnography
WEST, EYE
Polysomnography was performed using six-channel EEG (Electroencephalography) montage (F3-A2, F4-A1, C3-A2, C4-A1, O1-A2, and O2-A1) according to the 10–20 system. Eye movement and muscle tone were recorded through left and right electrooculographic and submental electromyographic electrodes that are respectively referenced to A2 and A1. EEG, electrooculographic, and electromyographic signals were recorded using a Comet Portable EEG system from Grass Technologies (Astro-Med, Inc., West Warwick, RI). The sampling rate and the storage rate were 800 and 200 Hz, respectively. The low-pass and high-pass filters were set at 35 and 0.3 Hz for the EEG signals and 70 and 10 Hz for the electromyographic signals. Electrode impedance was kept below 5 kΩ.Sleep was auto-scored in real-time in 30-sec epochs using the latest version of Z3Score cloud-based real-time autoscoring (The following sleep parameters were computed: TST, N1 latency (time from lights off to N1 onset), N2 latency, and durations of N1, N2, N3, and REM sleep.