Date of Award

Summer 2016

Document Type


Degree Name

Doctor of Philosophy (PhD)


Psychology and Behavioral Sciences

First Advisor

Walter Buboltz


Sleep is vital to survival and well-being. Adequate sleep, which is conceptualized in terms of quantity and quality, is positively related to a number of cognitive functions. In terms of length, it has been recommended that individuals in late adolescence and adulthood should receive no less than eight hours of sleep. Negative effects on higher-order mental processes have been found in states of sleep deprivation. Individuals who experience total sleep deprivation show decrements in performance on tasks of executive function (i.e. sustained attention, planning, and decision making). However, the effects of partial sleep deprivation on executive functions has not been fully examined and is under-studied in the scientific literature. Furthermore, research surrounding chronotype (morning or evening preference) suggests that time of day impacts performance on cognitive tasks. The literature is incomplete regarding the effects of partial sleep deprivation and chronotype preference on executive function. The aim of the current study is to examine these variables.

One hundred-five college students recruited from a university set in the Southern United States participated in this study. Sleep quality, which was assessed using the Pittsburgh Sleep Quality Index, the Sleep Hygiene Scale, and the Adult Sleep-Wake Scale, Chronotype, as assessed by the Morningness-Eveniningness Scale, and executive functions, as measured by the Sustained Attention to Response Task (SART) and the Tower of London Task (TOL) were used in this study. Self-report, paper-based measurements concerning sleep quality and morningness/eveningness preference were administered once, at the initial assessment period, and executive function performance was measured at three task administration times throughout the testing day. Group differences were assessed using MANOVA's, with between-subject analyses (ANOVA's) being conducted on the separate outcome variables to elucidate sleep group and chronotype preferences differences. Results indicated a significant interaction between sleep quality and morningness/eveningness preference, with good sleep quality students performing better on executive function tasks during their preferred time of day.