All ETDs from UAB

Advisory Committee Chair

David C Schwebel

Advisory Committee Members

Kristin Avis

Robin Lanzi

David Lozano

Carl E McFarland

Document Type

Dissertation

Date of Award

2013

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Introduction. Over 8,000 American adolescents ages 14 and 15 require medical attention due to pedestrian injury annually. Psychosocial factors contributing to pedestrian safety include reaction time, impulsivity, risk-taking, attention, and decision-making. These characteristics are also influenced by sleep restriction. Adolescents require 8.5 hours of uninterrupted sleep each night. Despite requiring more sleep than other children, adolescents often do not obtain adequate sleep due to delayed circadian, academic demands, extracurricular activities, media use, and minimal parental supervision. This combination of factors may place adolescents at risk for pedestrian injury. Method. This study investigated whether sleep restriction reduces adolescents' pedestrian safety. Using a within-subjects design, fifty-five 14- and 15-year-olds engaged in a virtual reality pedestrian environment in two conditions: a sleep restricted condition (4 hours sleep previous night) and an adequate sleep condition (8.5 hours sleep previous night). It was predicted that adolescents would be riskier pedestrians when sleep-deprived. Risk was displayed in a virtual pedestrian environment through increased numbers of close calls, hits, and missed safe opportunities, longer start delays and decreased gap sizes. Results. t-tests assessed pedestrian safety differences in both sleep conditions. After sleeping 4 hours, adolescents took more time to initiate crossings, crossed with less time to contact vehicles, experienced more hits/close calls and missed fewer safe opportunities to cross compared to the 8.5 hour condition. Age, gender, ethnicity and accumulated sleep debt were unrelated to pedestrian behavior. Discussion. When sleep restricted, adolescents took longer to recognize safe gaps in traffic and initiate crossings, crossed with less distance between them and oncoming cars, were hit or almost hit by cars more frequently, and missed fewer safe opportunities to cross the street. These results may be due to slower reaction time and decreased attention, impaired decision-making skills and increased risk-taking when fatigued. Overall, adolescents seem to exhibit more dangerous pedestrian behavior when sleep restricted than when adequately rested. This study has implications about the importance of adequate sleep in adolescents and should promote healthier sleep habits and inform policy decisions such as school start times.

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