Sleep and Academic Performance in Korean High School Students

ABSTRACT

BACKGROUND: The objective of this study was to quantify the sleep behavior of Korean high-school students and its relationship with academic performance. METHODS: Sleep surveys were completed by high-school students in Daegu, South Korea during September 2017. The questionnaires investigated factors such as sleep quality, sleep and wake schedules, nighttime smartphone use, and scores on a five-level grading scale pertaining to academic performance (A, 1–20%; B, 21–40%; C, 41–60%; D, 61–80%; E, 81–100%). The chi-squared test, independent t-test, analysis of variance, and regression analysis were used to analyze the results. RESULTS: The questionnaires were completed by 691 high-school students consisting of 279 (40.4%) boys and 412 (59.6%) girls. Poor sleep quality (Pittsburgh Sleep Quality Index [PSQI] ≥8.5) was identified in 111 (16.1%) students, and depressed mood (Hospital Depression Scale score ≥8) was identified in 254 (36.8%). Students with better academic performance tended to have lower PSQIs (A, 5.29±2.58; B, 5.41±2.98; C, 6.00±2.65; and D/E, 6.15±2.97), and the morningness-eveningness questionnaire scores were significantly higher in A-level students than in D- and E-level students. Regression analysis showed that leaving school early each day and greater nighttime smartphone use were significantly associated with worse academic performance in high-school students. CONCLUSIONS: This study found a close relationship between the sleep behavior of students and their academic performance. Students with better sleep quality, morningness, and less nighttime smartphone use tended to perform better academically. Lifestyle modification should be considered as an important factor for improving academic performance.