Neurobehavioral functions and sleep architecture during polyphasic and monophasic short sleep schedules

STUDY OBJECTIVES: To investigate how sleep architecture and neurobehavioral functions change during a polyphasic short sleep schedule and to compare these responses to those of a monophasic short sleep schedule with the same total sleep opportunity, as well as to those of a well-rested control group. METHODS: Forty healthy young adults (18 males, age: 18-35) were assigned to either the monophasic short sleep group, which had a single 2-h sleep opportunity, or the polyphasic short sleep group, which followed the "Uberman" sleep schedule and had six 20-min sleep opportunities distributed evenly across 24 h (1 every 4 h). Polysomnography was conducted during every sleep opportunity. Neurobehavioral functions were assessed at baseline (before the sleep opportunity manipulation started) and 6 times thereafter (once every 4 h). RESULTS: Both short sleep groups experienced greater subjective sleepiness, poorer vigilance, and lower positive mood as compared to a well-rested control group. Relative to the monophasic short sleep group, the polyphasic short sleep group showed greater vigilance impairment, particularly in the morning. This was accompanied by greater reductions in total sleep time, longer total sleep onset latency and wake after sleep onset, as well as greater proportions of N1 and N2 but lower proportions of N3 sleep in the polyphasic short sleep group relative to the monophasic short sleep group. CONCLUSIONS: In young adults, the "Uberman" polyphasic sleep schedule substantially reduces total sleep duration and sleep efficiency, even when compared to a monophasic sleep schedule with the same overall sleep opportunity, and may be associated with poorer neurobehavioral performance. Statement of Significance Polyphasic short sleep has been proposed to help retain a "scientifically required amount" of SWS and REM sleep, and optimize performance and mood despite the extended wake duration. We found that not only did the "Uberman" sleep schedule drastically shorten SWS and REM durations over a 24-h period, and degrade alertness, vigilance, and mood during the daytime, but its associated neurobehavioral deficits during the biological night, when one is normally asleep, were also prominent. Therefore, individuals will likely struggle cognitively and emotionally during both day and night, at least when they start adopting this sleep schedule. The long-term impacts of polyphasic sleep on sleep, daily functioning, and health remain to be extensively characterized.