Social jetlag in school students: evidence to suggest that sleep deprivation during work days is common

Associations of social jetlag with physical activity and sedentary behaviour in children and adolescents: A systematic review and meta-analysis

Sleep and daytime movement behaviours occur co-dependently with each other within a finite 24 h day. Sleep parameters other than sleep duration, such as social jetlag and chronotype, have been linked to health problems and unhealthy behaviours among children and adolescents. Given the increasing number of studies examining sleep timing/chronotype and weight-related behaviours, including physical activity and sedentary behaviour, in the past decade, this systematic review and meta-analysis collated and evaluated the evidence on the relationships of social jetlag and chronotype with physical activity and sedentary behaviour among children and adolescents aged 3-17 years. Seven databases were searched on 16 March 2022, and 52 studies were identified as eligible for inclusion, 47 of which were suitable for the meta-analysis. A positive association was found between social jetlag and screen media use (r = 0.14, 95% CI: 0.04-0.24; I2  = 96%; p = 0.008). The morning chronotype was associated with a higher level of physical activity and a lower level of sedentary behaviour than the evening chronotype. No relationship was found between social jetlag and physical activity. The magnitude of heterogeneity among the included studies was high. Further experimental studies are urgently required to understand how circadian preference or misalignment affects activity behaviours. Interventions to promote an active lifestyle in young populations should consider their circadian preference, especially among individuals with the evening chronotype.

Afternoon school shift is associated with increased risk of overweight/obesity in 11-14-year-old females with early and intermediate chronotype

OBJECTIVE

The purpose of this study was to compare the anthropometric and sleep-wake rhythm characteristics of schoolchildren that attend school in morning and afternoon school shifts.

METHODS

We recruited 18 481 individuals (females: 56.4%) aged 11 to 18 years old with an average age of 14.4 ± 1.7 years old. In total, 812 (4.2%) questionnaires were incomplete. The self-reported height and weight were used to assess the sex- and age-corrected body mass index of the participants. The Munich ChronoType Questionnaire was used to assess the chronotype, social jetlag, and sleep duration of the participants.

RESULTS

In total, 12.6% of the participants were affected by overweight or obesity. The overweight and obesity incidence rate was higher among the students studying in the afternoon (odd ratio [95%CI]: 1.33 [1.16-1.52]). The afternoon school shift had a negative impact on the anthropometric indicators only in the 11-14-year-olds (1.29 [1.11-1.50]) and girls (1.26 [1.04-1.54]) with an early (1.27 [1.03-1.56]) and intermediate (1.30 [1.07-1.58]) chronotype.

CONCLUSION

The data obtained indicated that the afternoon school shift is not ideal, especially for female children and adolescents under 15 years old with an early and intermediate chronotype.

Persistent, High Levels of Social Jetlag Predict Poor Weight Outcomes in a Weight Gain Prevention Study for Young adults

INTRODUCTION

Social jetlag (SJL), the discrepancy in sleep timing between weekdays and weekends, is associated with higher BMI and cardiometabolic risk and is common in young adults. We examined whether chronic SJL impacts weight gain in young adults participating in a weight gain prevention trial.

METHODS

Young adults (n = 599, age 18-35; BMI: 21.0-30.9 kg/m²) completed assessments at 0, 4, 12, and 24 months. Multilevel mixed growth models were used to examine (1) associations between demographics and longitudinal SJL and (2) longitudinal SJL as a predictor of weight change and cardiometabolic outcomes. SJL was assessed as a continuous and clinically-significant dichotomous (< vs. ≥2 h) variable.

RESULTS

38% of participants had clinically-significant SJL at ≥ 1 timepoints (Baseline M ± SD = 1.3±0.89). Younger (b=-0.05, p < 0.001), female (b = 0.18, p = 0.037) and Black (compared to White, b = 0.23, p = 0.045) participants were more likely to have greater SJL. Individuals with high SJL (≥ 2 h; between-person effect) were more likely to have greater weight gain over 2 years (b = 0.05, p = 0.028). High SJL did not affect the rate of change in waist circumference or cardiometabolic markers over time.

CONCLUSIONS

High SJL is associated with greater weight gain over time. Reducing SJL may positively impact weight status in young adults.

Social Jetlag in adolescents: From a nursing perspective

PROBLEM

Social Jetlag (SJL) is a condition leading to many important physical, mental, behavioral, and cognitive problems in adolescents.

METHODS

The sample of this study, which used a descriptive and correlational design, consisted of 247 high school students. The SJL parameters were informed by the literature, while chronotype was identified using the Morningness-Eveningness Scale for Children. The factors associated with SJL were determined using a structured questionnaire.

FINDINGS

Students' SJL value was 2 h 10 min ± 01:11. As students' tendency to be an evening chronotype increased, the SJL value increased, as well (r = -0.472; p < 0.001). In terms of SJL, student's grade level (β = -0.167; p = 0.004) and chronotype (β = -0.438; p < 0.001) were a negative risk factor, while spending time in bed with TV/computer/smartphone before sleeping (β = 0.127; p = 0.031) was a positive risk factor.

CONCLUSIONS

The students had a high SJL value. The results might be useful for nurses to develop intervention strategies to improve adolescents sleep habits.

Social Jetlag Is Associated with the Frequency of Consumption of Sugar-Sweetened Beverages and a High BMI Percentile in Adolescents: Results of the Cross-Sectional Family Life, Activity, Sun, Health, and Eating (FLASHE) Study

BACKGROUND

Social jetlag (SJL) occurs in adolescents due to misalignment of the biological and social clocks, so that most teens wake up earlier than their biological clocks on weekdays and delay bedtime and wake up time on weekends. This shift in sleep timing among adolescents is associated with an adverse endocrine and behavioral risk profile, in addition to increased food consumption and increased body mass index (BMI).

OBJECTIVE

The aim of this study was to determine the association between SJL, and the frequency of consumption of multiple food and beverage groups and BMI percentile in adolescents.

DESIGN

Publicly available data from the cross-sectional Family Life, Activity, Sun, Health, and Eating (FLASHE) study were analyzed.

PARTICIPANTS

Participants from the FLASHE study were recruited from all regions of the United States between April and October 2014. Among the 1,581 adolescents aged 12 through 17 years in the original study, 1,556 with complete sleep data were analyzed.

MAIN OUTCOME MEASURES

The difference between the frequency of dietary consumption according to the Dietary Screener Questionnaire and BMI percentile was assessed in adolescents grouped according to SJL, as follows: no SJL: less than 1-hour difference; mild SJL: 1- to 2-hour difference; and severe SJL: more than 2-hour difference.

STATISTICAL ANALYSES PERFORMED

Differences in the frequency of food consumption were analyzed using the Kruskal-Wallis test. Secondary outcomes were analyzed using logistic regression models.

RESULTS

Daily consumption frequency of sugar-sweetened beverages and fruits and vegetables differed among the 3 groups. Likewise, the BMI percentile differed among the 3 groups and was highest in the severe SJL group. Those in the severe SJL group had a 1.84-fold higher probability of having overweight or obesity (95% CI 1.83 to 1.84) than those in the no SJL group.

CONCLUSIONS

Severe SJL is associated with a higher frequency of sugar-sweetened beverage consumption and higher odds of having overweight or obesity compared with no SJL in adolescents.

Beyond Sleep Duration: Bidirectional Associations Among Chronotype, Social Jetlag, and Drinking Behaviors in a Longitudinal Sample of US High School Students

Inadequate sleep and problematic drinking are prevalent among high school students and are significant public health issues. Inadequate sleep may contribute to alcohol use through impairments in emotion regulation or cognitive functioning, whereas alcohol use may lead to inadequate sleep through the biological effects of alcohol or social influences. However, the directionality of the associations between sleep and drinking variables remains unclear as most prior studies were cross-sectional. This study utilizes longitudinal data from the NEXT Generation Health Study to examine bidirectional associations between alcohol use and sleep adequacy in a nationally representative sample across 3 years of high school. Students reported usual bedtimes and waketimes for scheduled- and free-days, alcohol use, and heavy episodic drinking. Estimates of sleep duration, chronotype, and social jetlag were calculated. Cross-lagged autoregressive models revealed evidence of alcohol use predicting subsequent sleep duration and timing, and sleep timing predicting subsequent alcohol use. Specifically, previous-wave alcohol use predicted shorter free-day sleep duration and later chronotype at 11th and 12th grade, and more social jetlag at 12th grade; similar results were obtained for heavy episodic drinking. Eleventh grade social jetlag predicted subsequent year current alcohol use; eleventh grade chronotype and social jetlag predicted subsequent year heavy episodic drinking. Bidirectional findings suggest that alcohol use and sleep may reflect mutually reinforcing life style choices. Understanding these bidirectional associations could inform risk prevention interventions. Given the implications of poor sleep for adolescents, further research on possible social influences on the alcohol-sleep relations is merited. Clinical Trial Registration: NCT01031160.