Secular trends in sleep and circadian problems among adolescents in Hong Kong: From 2011-2012 to 2017-2019.

OBJECTIVE: The study aimed to investigate secular trends in sleep and circadian problems in Hong Kong Chinese adolescents. METHODS: This study analyzed cross-sectional data from two large-scale school-based sleep surveys conducted in 2011-2012 and 2017-2019. Sleep and circadian problems, including sleep-wake pattern, insomnia, chronotype, social jetlag, daytime sleepiness, and other sleep-related factors, were compared between two survey years. RESULTS: A total of 8082 adolescents (5639 students in 2011-2012 [Mean age: 14.4 years, 50.9% boys] and 2443 students in 2017-2019 [Mean age: 14.7 years, 54.0% boys]) were included in this 7-year study. The average time in bed of Hong Kong adolescents decreased from 8.38 hours to 8.08 hours from 2011-2012 to 2017-2019. There was a 0.28-hour delay in weekday bedtime, 0.54-hour advance in weekend wake-up time, and a 0.36-hour decline in average time in bed, resulting in increased trends of sleep loss (Time in bed <8h: OR = 2.06, 95%CI: 1.44-2.93, p < 0.01; Time in bed <7h: OR = 2.73, 95%CI: 1.92-3.89, p < 0.01), daytime sleepiness (OR = 1.70, 95%CI: 1.34-2.16, p < 0.01), and evening chronotype (OR = 1.26, 95%CI: 1.08-1.48, p < 0.01). The increased trend in insomnia disorder, however, was insignificant when covariates were adjusted. CONCLUSION: A secular trend of reduced time in bed, delay in weekday bedtime, advance in weekend wake-up time, increase in evening chronotype and daytime sleepiness from 2011-2012 to 2017-2019 were observed. There is a timely need for systematic intervention to promote sleep health in adolescents.

The impact of sleep-corrected social jetlag on mental health, behavioral problems, and daytime sleepiness in adolescents.

STUDY OBJECTIVES: This study aimed to examine the effect of sleep-corrected social jetlag (SJLsc) on mental health, behavioral problems, and daytime sleepiness in adolescents. METHODS: This was a cross-sectional study which included 4787 adolescents (Mean age: 14.83±1.6y, 56.0% girls) recruited from 15 secondary schools in Hong Kong. SJLsc was defined as the absolute difference between sleep-corrected midsleep on weekdays and weekends, at which the sleep debt has been considered. It was classified into three groups: low-level ("LSJLsc", <1h), mid-level ("MSJLsc", ≥1h and <2h), and high-level of SJLsc ("HSJLsc", ≥2h). Adolescents' mental health, behavioral problems and daytime sleepiness were measured by the General Health Questionnaire (GHQ-12), the Strengths and Difficulties Questionnaire (SDQ) and the Pediatric Daytime Sleepiness Scale (PDSS). Logistic regression analysis and restricted cubic spline regression (RCS) analysis were applied with consideration of confounders including age, gender, puberty and sleep problems. RESULTS: Nearly half (46.9%) of adolescents had SJLsc for at least 1 h. Greater SJLsc was associated with more behavioral difficulties (MSJLsc: OR: 1.20, p = 0.03; HSJLsc: OR: 1.34, p = 0.02) when controlling for age, sex, puberty, chronotype, insomnia, and time in bed. There was a dose-response relationship in which higher SJLsc had an increased risk of conduct problems and hyperactivity, while only high-level SJLsc was associated with a peer relationship problem. In RCS analysis, SJLsc was associated with a higher likelihood of behavioral difficulties (p = 0.03) but not poor mental health or daytime sleepiness. CONCLUSIONS: Sleep-corrected social jetlag was a unique risk factor for behavioral problems in adolescents. Our findings highlighted the need for interventions to promote healthy sleep-wake patterns in school adolescents.