Background and Objective: The purpose of this study was to investigate the effect of delaying school start time on sleep quality, emotion and performance in Korean adolescents.
Methods: Data were collected in 2 months and 12 months each using self-administering questionnaires by 238 students at a middle school located in Gyeonggi province. Questionnaires were composed of demographic data and various sleep and emotion related scales including Pittsburgh Sleep Quality Index(PSQI). Students were divided into two groups of increased or decreased total sleep time(TST). Wilcoxon signed rank test was used to identify significant differences in 2 months vs. 12 months in sleep parameters, emotions and school performance in both groups.
Results: In both groups, PSQI duration, PSQI total score and sleep efficiency significantly improved from 2 month to 12 month data. There were significant improvements in depression, stress, behavioral aggression, and verbal aggression in increased TST group. Increased TST group showed advancements in subjective feeling of happiness and number of being being late for school per week between baseline and 12 months. Decreased TST group showed significant differences in subjective feeling of happiness, number of being being late for school per week, sleepiness during class, concentration on class, relationship with friends, energy in daily life, general feeling in school, willingness to go to school, and anger in school life.
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