Association between Sleep Time and Blood Pressure in Korean Adolescents: Cross-Sectional Analysis of KNHANES VII

Background: Hypertension is highly related to sleep, and there have been a number of studies on sleep deprivation and the occurrence of hypertension. However, there is still insufficient research on the relationship between hypertension and various factors related to sleep. Thus, this study attempted to investigate the relationship between hypertension and sleep time-related variables in Korean adolescents. Methods: A total of 1470 adolescents (709 girls and 761 boys) between 12 and 18 years of age were enrolled through the Seventh Korea National Health and Nutrition Examination Survey (KNHANES VII). The systolic and diastolic blood pressure were measured. Sleep time-related variables such as sleep onset time, wake time, and sleep duration (weekday and weekend, each) were also investigated using a questionnaire. We performed multivariate regression analyses to determine the independent effects of the variables. Results: Systolic blood pressure was negatively correlated with the wake time (r = −0.081; p = 0.002) and sleep onset time (r = −0.088; p = 0.001) on weekends. There was a positive correlation between diastolic blood pressure and weekday sleep onset time (r = 0.158; p = 0.000) and weekend sleep onset time (r = 0.184; p = 0.000). The sleep duration on weekdays and weekends showed a negative correlation (r = −0.136; p = 0.000, r = −0.088; p = 0.001, respectively). In the multivariate linear regression analysis results, the sleep onset time on weekends was significantly correlated with elevated diastolic blood pressure. Conclusions: Delayed sleep onset time on weekends was significantly associated with increased diastolic blood pressure in Korean adolescents. Further investigation is needed to confirm the clinical significance of these findings.

Participation in Physical Education Classes, Psychological Well-Being, and Sleep Satisfaction Among South Korean Adolescents

PURPOSE: This study aimed to examine the associations between participation in physical education (PE) classes and the psychological well-being and sleep satisfaction of Korean adolescents.METHODS: Cross-sectional data from 127,804 Korean adolescents (aged 12–18 years) who participated in the 2016 and 2017 Korea Youth Risk Behavior Web-based Surveys (KYRBS) were analyzed. The exploratory variable was the frequency of participation in PE classes every week, while the dependent variables included the psychological well-being and sleep satisfaction, as assessed by the KYRBS questionnaire. Sex- and grade-stratified logistic regression analyses were conducted to generate the odds ratios (ORs) and 95% confidence intervals (CI).RESULTS: Overall 16.9% of adolescents reported that they did not participate in PE classes while 33.0% reported participating for more than three times a week. After adjusting for the academic achievements, family’s economic status, consumption frequency of breakfast and highly caffeinated drinks, and physical activity level, a greater participation in the PE classes was found to be associated with happiness in a dose-response fashion in both sexes and grades (p<.05). As for stress, participation in the PE classes for more than three times a week was associated with less/no stress in boys (OR: 1.16, 95% CI: 1.02–1.31, p<.05) and high school students (OR: 1.22, 95% CI: 1.03–1.44, p<.05). Moreover, greater participation in the PE classes was associated with a lower odds of reporting sleep satisfaction in a linear fashion among high school students.CONCLUSIONS: More frequent participation in PE classes was associated with the psychological well-being and sleep satisfaction in a large sample of Korean adolescents. Increasing the number of mandatory PE sessions is a promising strategy for promoting the psychological well-being of Korean adolescents.