Sleep architecture of consolidated and split sleep due to the dawn (Fajr) prayer among Muslims and its impact on daytime sleepiness

Background: Muslims are required to wake up early to pray ( Fajr ) at dawn (approximately one and one-half hours before sunrise). Some Muslims wake up to pray Fajr and then sleep until it is time to work (split sleep), whereas others sleep continuously (consolidated sleep) until work time and pray Fajr upon awakening. Aim: To objectively assess sleep architecture and daytime sleepiness in consolidated and split sleep due to the Fajr prayer. Setting and Design: A cross-sectional, single-center observational study in eight healthy male subjects with a mean age of 32.0 ± 2.4 years. Methods: The participants spent three nights in the Sleep Disorders Center (SDC) at King Khalid University Hospital, where they participated in the study, which included (1) a medical checkup and an adaptation night, (2) a consolidated sleep night, and (3) a split-sleep night. Polysomnography (PSG) was conducted in the SDC following the standard protocol. Participants went to bed at 11:30 PM and woke up at 7:00 AM in the consolidated sleep protocol. In the split-sleep protocol, participants went to bed at 11:30 PM, woke up at 3:30 AM for 45 minutes, went back to bed at 4:15 AM, and finally woke up at 7:45 AM. PSG was followed by a multiple sleep latency test to assess the daytime sleepiness of the participants. Results: There were no differences in sleep efficiency, the distribution of sleep stages, or daytime sleepiness between the two protocols. Conclusion: No differences were detected in sleep architecture or daytime sleepiness in the consolidated and split-sleep schedules when the total sleep duration was maintained.