The PSG recordings are detailed in a previous publication [27] . The sleep studies were performed at the SDC. Alice 5 diagnostic equipment (Philips/Respironics, Inc., Murrysville, Pennsylvania, USA) was used for data acquisition. The subjects were asked to avoid napping during the sleep study day. During BL, the study began at 23:00 and was completed at 07:00. During BLF and Ramadan, the study began at 2300. During Ramadan, the participants were awakened at 03:00 for Suhur, and the study was resumed from 03:45 until 07:45. During BLF, the participants were awakened at 03:15 for Suhur (to account for the shift in dawn prayer time), and the study was resumed from 04:00 until 07:45.
During the study, the following parameters were monitored: four electroencephalography (EEG) channels (C1-A4, C2-A3, O1-A4, and O2-A3), chin electromyography (EMG), electrooculography (EOG) (eye movement), EKG, oxygen saturation, chest and abdominal wall movements, air flow (thermistor), body position, and a microphone for the recording of snoring. “Stage shifts” was defined as total number of changes in sleep state from lights out to lights on. Arousal index, which is a measure of sleep fragmentation, was defined as the number of arousals per 1 hour of sleep.
During the study, the following parameters were monitored: four electroencephalography (EEG) channels (C1-A4, C2-A3, O1-A4, and O2-A3), chin electromyography (EMG), electrooculography (EOG) (eye movement), EKG, oxygen saturation, chest and abdominal wall movements, air flow (thermistor), body position, and a microphone for the recording of snoring. “Stage shifts” was defined as total number of changes in sleep state from lights out to lights on. Arousal index, which is a measure of sleep fragmentation, was defined as the number of arousals per 1 hour of sleep.