Master of Science
Dr. Joseph Dzierzewski
Background: Daytime sleepiness is a common and debilitating phenomenon. Sleepiness is associated with increased symptoms of insomnia, depression, anxiety, and fatigue. Daytime sleepiness is commonly associated with cognitive performance, including performance on the Psychomotor Vigilance Test (PVT). The PVT includes performance feedback, and that feedback may influence an individual’s report of their sleepiness. Whether the feedback on the PVT influences an individual's self-reported sleepiness is unknown. This study sought to investigate how sleepiness was associated with clinical symptoms and performance, whether there are sex differences in sleepiness, and whether manipulating feedback on the PVT influenced an individual’s self-reported sleepiness.
Methods: Participants were 115 adults (Mage = 20.8 years), mostly female (59%), and who had completed at least some college (75%) recruited from Brigham Young University and the surrounding community. Participants completed various questionnaires about sleep and mood before and after completing a 10-minute PVT. Before the PVT, participants were randomly assigned to one of four feedback conditions: (1) PVT with reaction time shown, (2) PVT without reaction time shown, (3) PVT with 2 category descriptive feedback, and (4) PVT with 8 category descriptive feedback. Sessions with participants were conducted over Zoom due to the COVID-19 pandemic. Pearson’s correlations were conducted to investigate the associations of sleepiness, t-tests were conducted to investigate sex differences in sleepiness, linear regressions were used to investigate whether sleepiness predicted PVT performance and whether PVT performance predicted sleepiness after the PVT, and an Analysis of Covariance (ANCOVA) was conducted to investigate whether the four feedback conditions influenced an individual’s self-reported sleepiness.
Results: Self-reported sleepiness was significantly correlated with symptoms of insomnia, depression, anxiety, and fatigue. Two t-tests were conducted to investigate sex differences in self-reported sleepiness assessed before the PVT and after the PVT. Women reported significantly higher sleepiness than men both before and after the PVT (t(113) = 2.824, p = .006; t(113) = 2.846, p = 005). None of the associations between sleepiness and clinical symptoms significantly differed between men and women. Self-reported sleepiness was not significantly correlated with PVT performance. Sleepiness did not predict PVT performance while PVT performance was partially moderated by group in predicting sleepiness after the PVT. Sleepiness after the PVT was not significantly different between groups when accounting for sleepiness before the PVT (F (3,110) = 0.691, p = .560).
Conclusion: Self-reported sleepiness was observed to be positively associated with various symptoms of clinical disorders including insomnia, depression, fatigue, and anxiety in line with previous findings. Women reported significantly higher sleepiness than men both before and after the PVT but the associations between sleepiness and the other clinical disorders were not significantly different between women and men, which may suggest differences in how women and men respond to sleepiness and report their difficulties with sleepiness. Surprisingly, no association between self-reported sleepiness and performance on the PVT was demonstrated in this study. Experimentally manipulating performance feedback on the PVT was not shown to influence sleepiness ratings reported after the PVT, which may suggest that manipulating performance feedback does not impact an individual’s self-reported sleepiness. Further research into how performance and sleepiness are associated and whether feedback, or the absence thereof, impacts self-reported sleepiness is needed. Such research could elucidate what influences an individual’s recognition and report of their sleepiness, which may have implications for sleep disorders and promoting sleep health among the population.
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