THE INFLUENCE OF CUMULATIVE SLEEP RESTRICTION ON HUMAN PERFORMANCE: EXAMINATION OF BRAIN DYNAMICS AND SUSTAINED ATTENTION

Abstract

Sustained attention (SA) impacts nearly every aspect of human performance. From the exactness of performing brain surgery to safely driving from one location to another, the ability to concentrate on a task for a period of time is important for success in work, school, relationships, and individual activities. As a key component of executive function (EF) and psychomotor performance, SA can be affected by many mental and physical processes. One process that can impact SA is restricted sleep, which is becoming more relevant in our ever-evolving technological society. Numerous studies have examined the impact of short bouts of restricted sleep on response time, a measure of SA, but few studies have examined the impact of the accumulating effect of sleep restriction (SR) on response time and brain dynamics as measured with electroencephalography (EEG). As part of a larger 40-day study, eight healthy participants (five female, average age 27.75) were observed for seven consecutive days and nights in a sleep lab, where they spent five hours in bed per night and engaged in numerous psychomotor vigilance tests (PVT), an indicator of SA, as part of their daytime activities. Through multiple one-factor ANOVAs, response time significantly slowed, and brain dynamic changes occurred, measured by slow wave activity (SWA) maxima change in the Fz electrode, located in the midline frontal region, over the course of the entire week of continual SR compared to an extended sleep night. Employing mixed method effects revealed a statistically significant relationship between response time and SWA maxima differences. The data show that not only does response time increase the day after rising first and last SWA maxima levels converge (i.e., flattening of the line slope connecting these values) caused by short bouts of SR, but these phenomena continue this progression with prolonged SR. Over the course of the week-long SR, the final SWA maximum increased at a higher rate than the first SWA maximum, leading to the maxima difference shrinking as response time increases. These findings indicate that brain dynamics highlight less restorative sleep occurring alongside a lack of sustained attention when sleep is restricted on a consistent basis.