Sleep patterns and school performance of Korean adolescents assessed using a Korean version of the pediatric daytime sleepiness scale

Abstract

Purpose: Korean adolescents have severe nighttime sleep deprivation and daytime sleepiness because of their competitive educational environment. However, daytime sleep patterns and sleepiness have never been studied using age-specific methods, such as the pediatric daytime sleepiness scale (PDSS). We surveyed the daytime sleepiness of Korean adolescents using a Korean translation of the PDSS. Methods: We distributed the 27-item questionnaire, including the PDSS and questions related to sleep pattern, sleep satisfaction, and emotional state, to 3,370 students in grades 5-12. Results: The amount of nighttime sleep decreased significantly with increasing age. During weekday nights, 5- 6th graders slept for 7.95 (1.05) h, 7-9th graders for 7.57 (1.05) h, and 10-12th graders for 5.78 (1.13) h. However, the total amounts of combined daytime and nighttime sleep during weekdays were somewhat greater, 8.15 (1.12) h for 5- 6th graders, 8.17 (1.20) h for 7-9th graders, and 6.87 (1.40) h for 10-12th graders. PDSS scores increased with age, 11.89 (5.56) for 5- 6th graders, 16.57 (5.57) for 7-9th graders, and 17.71 (5.24) for 10-12th graders. Higher PDSS scores were positively correlated with poor school performance and emotional instability. Conclusion: Korean teenagers sleep to an unusual extent during the day because of nighttime sleep deprivation. This negatively affects school performance and emotional stability. A Korean translation of the PDSS was effective in evaluating the severity of daytime sleepiness and assessing the emotional state and school performance of Korean teenagers. © 2010 by The Korean Pediatric Society.