Date of Award
Contemporary understanding of the brain indicates that a reciprocal relationship exists between mind and body. Biological functioning adjusts to the consequences of our behavior and our behavior is influenced by our biology. This is the case with the stress responsivity system. The stress hormone cortisol follows a biologically-predetermined daily cycle of secretion (controlled by circadian rhythm) that correlates with expected activity throughout the day, however this cycle can accommodate to different environmental changes that can occur. It has been noticed that individuals who report stress problems also report sleep problems. I hypothesized that sleep quality can predict maladjustments in cortisol’s rhythm. All participants provided saliva samples and had to take the Pittsburgh Sleep Quality Index (PSQI). Salivivay cortisol was measured via was enzyme-immuno-assayed for cortisol. I analyzed the data for three independent studies: (1)12 samples were taken for basal and lab days in 65 individuals. People who scored worse in total PSQI showed decreased stress reactivity (γ 21=-.02, t(63)=-2.27, p=0.026) and faster recovery (γ31=-0.102, t(608)=-2.044, p=0.041). (2)6-8 samples per day across 5 days in 120 maltreated or control adolescents. I used a 3-level hierarchical linear model to examine rhythms within each day and within each individual. The cortisol rhythm was flattened on days when adolescents had poor sleep latency (β;=.013, p=.025 for time-since-waking, β=-.0008, p=.039 for quadratic time-since-waking). (3) 10 samples were taken in 44 skydivers for jumping and basal days. Those who scored worse in sleep latency had slower reactivity (γ31=-0.16, t(284)=-3.701, p<.001) and slower recovery (γ31=0.22, t(284)=3.311, p<0.001). Stress and sleep problems are related to cognitive and physiological issues; finding an appropriate connection between them can be elemental in preventing problems.
Velasquez, Miguel A., "Reciprocal Relation Between Psychophysiological Patterns of Stress Responsivity and Sleep" (2014). Senior Honors Theses. 61.