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

Social jetlag is associated with body mass (BMI) in children aged 2-8years: A cross-sectional analysis

OBJECTIVE

Social jetlag is associated with higher body mass index (BMI) in adults, adolescents, and older children. However, no research to date has addressed social jetlag and body mass index in early childhood. This study investigated the association between social jetlag and BMIz in children aged 2-8years.

METHODS

Cross-sectional data were leveraged from 1122 children (M=5.6±1.7years, 48.8% females) from the NIH Environmental influences on Child Health Outcomes (ECHO) study between 2016 and 2021. Sleep timing was parent-reported. Social jetlag was calculated as the absolute difference in weekend-weekday sleep midpoint. Objective measurements of children's height and weight were used to compute age- and sex-adjusted BMIz. Regression models tested the association between social jetlag and BMIz, adjusting for sociodemographic and sleep covariates.

RESULTS

After controlling for age, sex, race and ethnicity, primary caregiver education, and average nighttime sleep duration, social jetlag was positively associated with BMIz (β=0.126, 95% CI: 0.004-0.249, p=.043). Children with ≥1-h social jetlag had higher average BMIz and had 66% higher odds of being overweight or obese (OR=1.66, 95% CI: 1.13-2.46, p=.01), compared with children with no social jetlag.

CONCLUSIONS

Social jetlag may contribute to higher BMIz in young children, similar to findings in older children, adolescents, and adults. At least 1 hour of social jetlag may increase children's odds of being overweight or obese. Future research is needed to test causality and whether reducing social jetlag can lead to healthy weight-related outcomes.

The hidden clock: how chronotype is related to depression, anxiety, and stress in adolescents - insights from the EHDLA study

BACKGROUND

Depression, anxiety, and stress symptoms are common among adolescents; however, studies exploring their relationship with chronotype in European youth populations is scarce. This study aimed to evaluate the association between chronotype status and depression, anxiety, and stress symptoms in adolescents.

METHODS

A secondary analysis of the Eating Healthy and Daily Life Activities (EHDLA) cross-sectional study was performed in 703 adolescents (56.3% girls) between 12 and 17 years from the Valle de Ricote, Spain. Chronotype preference was assessed using the Morningness/Eveningness Scale in Children (MESC), while symptoms were evaluated using the Depression, Anxiety, and Stress Scale (DASS-21). A robust generalized linear regression model was used to evaluate the associations between chronotype prefernces and symptoms of depression, anxiety and stress in adolescents.

RESULTS

After adjusting for potential covariates (sex, age, socioeconomic status, body mass index, sleep duration, physical activity, sedentary behavior, and energy intake), the highest probability of having depression, anxiety, and stress was identified in those with an eveningness chronotype preference (depression: 27.4%, 95% confidence interval [CI] 17.5-40.1%; anxiety: 28.5%, 95% CI 18.6-41.0%; stress: 47.6%, 95% CI 34.1-61.5%). Conversely, the lowest probability was observed in adolescents with a morningness chronotype preference (depression: 11.9%, 95% CI 8.3-16.8%; anxiety: 15.4%, 95% CI 11.2-28.9%; stress: 19.5%, 95% CI 14.7-25.5%). Significant differences were found when comparing participants with the eveningness chronotype to those with a morningness or intermediate chronotype preference (p < 0.05 for all comparisons).

CONCLUSIONS

Depression, anxiety, and stress symptoms were more likely in adolescents with an eveningness chronotype preference than in those with morningness or intermediate chronotypes. Chronotype preferences should be taken into account for developing interventions that promote better mental health and healthy sleep habits in adolescents.

The effect of chronotype characteristics on cardiovascular health behaviors in school-age children: A cross-sectional study

This study aimed to investigate the effect of chronotype characteristics on cardiovascular health behaviors in school-age children. This descriptive, correlational, and cross-sectional study involved 424 school-age children aged 10-12. Participants completed the Morningness-Eveningness Scale for Children (MESC) and the Cardiovascular Health Behavior Scale for Children (CHBSC). The results were analyzed using descriptive statistics and multivariate regression analysis, adhering to ethical principles throughout the study. The mean MESC and CHBSC scores for the children were 28.37 ± 5.20 and 57.04 ± 11.34, respectively. 53.8% of the children exhibited moderate cardiovascular health behaviors, while 79% had a moderate chronotype. A moderate negative correlation was observed between MESC and CHBSC scores (r = -0.39, p < 0.01), with the MESC explaining 16% of the variance in cardiovascular health behaviors. The MESC influenced cardiovascular health behaviors and its subscales nutrition, exercise, sedentary lifestyle, self-love, and stress subscales. Most school-age children display intermediate chronotype characteristics and cardiovascular health behaviors. Children with an evening chronotype demonstrated lower levels of cardiovascular health behaviors. Chronotype characteristics had the most negative impact on the sedentary lifestyle aspect of cardiovascular health behaviors. Furthermore, chronotype plays a significant role in explaining the key factors influencing cardiovascular health behaviors.

Association between social jetlag and anxiety symptoms: Findings from a nationally representative sample of the Korean working population

OBJECTIVES

Social jetlag (SJL), which arises from the misalignment of biological and social rhythms, is associated with adverse health outcomes. We explored the association between SJL and anxiety symptoms in Korean workers.

METHODS

This cross-sectional study included a nationally representative sample, consisting of 2731 adult workers. SJL was calculated as the absolute difference in the midpoint between sleep onset and offset times on workdays and free days. The Generalized Anxiety Disorder-7 scale was used to assess anxiety symptoms. Logistic regressions were used to estimate the odds ratios (ORs) and 95 % confidence intervals (CIs).

RESULTS

Among the sample, 66.5 % individuals had 0-59 min of SJL, 22.6 % had 60-119 min of SJL, and 10.9 % had ≥120 min of SJL. The prevalence of anxiety symptoms was 3.4 % for those with 0-59 min of SJL, 3.2 % for those with 60-119 min of SJL, and 7.7 % for those with ≥120 min of SJL. Workers with ≥120 min of SJL, compared with those with 0-59 min of SJL, were associated with an increase in the odds of having anxiety symptoms (OR:2.04, 95 % CI:1.10-3.78). A 1-h increase in SJL is associated with a 1.35-fold increase in the odds of anxiety symptoms (95 % CI:1.04-1.75). This positive association remained robust after adjusting for the effect of sleep deprivation using a sleep-corrected formula.

CONCLUSION

≥2 h of SJL is associated with anxiety symptoms in Korean workers. Policy measures are required to mitigate excess SJL and monitor the mental health of workers with high SJL levels.

Is Social Jetlag Associated With Physical Fitness Among Spanish Adolescents? Insights From the EHDLA Study

BACKGROUND

The misalignment of sleeping times during weekdays/weekends (i.e., social jetlag) is particularly common among adolescents and plausibly associated with their physical fitness. However, literature on this topic is scarce. Therefore, this study aimed to investigate the association between social jetlag and physical fitness in Spanish adolescents.

METHODS

A secondary analysis was conducted on cross-sectional data from the Eating Healthy and Daily Life Activities (EHDLA) study among 812 adolescents (54.9% girls) aged 12-17 years from the Valle de Ricote (Region of Murcia, Spain). Social jetlag was calculated from self-reported data on bedtimes and wake times for weekdays and weekends. Physical fitness was evaluated with the Assessing the Levels of PHysical Activity and Fitness (ALPHA-FIT) for children and adolescents and included cardiorespiratory fitness, muscular fitness, speed agility, and flexibility.

RESULTS

The analysis revealed significant negative associations between worse social jetlag and detrimental overall physical fitness (unstandardized beta coefficient [B] = -0.06, 95% confidence interval [CI]: -0.09, -0.02; p = 0.002), cardiorespiratory fitness (B = -1.28; 95% CI -2.22, -0.34; p = 0.008), and lower body muscular fitness (B = -2.01; 95% CI -3.90, -0.12; p = 0.038) after the adjustment for potential covariates (age, sex, socioeconomic status, physical activity level, sedentary behavior, nocturnal sleep duration, energy intake, and body mass index). In contrast with other fitness components, a significant positive association was identified between social jetlag and speed agility (B = 0.07; 95% CI 0.00, 0.14; p = 0.049).

CONCLUSIONS

In adolescents, social jetlag is significantly linked to poorer physical fitness, especially for cardiorespiratory fitness and lower-body muscular fitness. Maintaining regular and well-synchronized sleep could be crucial for optimizing physical health and preventing the decline of physical fitness during adolescence.

The Role of the Chronotype in Developing an Excessive Body Weight and Its Complications-A Narrative Review

The chronotype, the personal predisposition towards morning or evening activities, significantly influences health conditions, sleep, and eating regulations. Individuals with evening chronotypes are often at a higher risk for weight gain due to misalignment between their natural tendencies of functioning and social schedules, resulting in insufficient sleep, disruptions in eating habits, and decreased physical activity levels. Often, impaired glucose tolerance and changes in melatonin, adiponectin, and leptin secretion, along with alterations in the clock gene functions in subjects with evening preferences, may be predisposed to obesity. These disturbances contribute to metabolic dysregulation, which may lead to the subsequent onset of obesity complications, such as hypertension, type 2 diabetes, sleep apnea, and liver diseases. Targeting critical components of the circadian system and synchronizing people's chronotypes with lifestyle conditions could deliver potential strategies for preventing and treating metabolic disorders. Thus, it is recommended to take a personalized chronobiological approach to maintain a normal body weight and metabolic health. Nevertheless, future studies are needed to identify the clear mechanisms between the chronotype and human health. This article provides a narrative review and discussion of recent data to summarize studies on the circadian rhythm in the context of obesity. The manuscript represents a comprehensive overview conducted between August and November 2024 using the National Library of Medicine browser (Medline, Pub-Med, Web of Science).

Association between social jetlag and leisure-time physical activity and muscle strengthening exercise in young adults: findings from a nationally representative sample in South Korea

OBJECTIVES

Social jetlag (SJL), which is characterised by a misalignment between biological and social time, is associated with cardiometabolic risk factors. This study investigated the relationship between SJL, leisure-time physical activity (LTPA) and muscle strengthening exercise (MSE) in young adults.

STUDY DESIGN

This was a cross-sectional study.

METHODS

This cross-sectional study included a nationally representative sample of young adults aged 19-29 years (n = 2113). SJL was calculated as the difference in the midpoint of sleep onset and offset time between weekdays and weekends. The dependent variables were engagement in ≥150 min/week of moderate-to-vigorous LTPA and engagement in MSE ≥2 days/week based on guidelines provided by the World Health Organisation. Logistic regression analysis was performed to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Non-linear relationships were estimated using restricted cubic spline regression.

RESULTS

The study population comprised 975 men and 1138 women. Among participants, 4.6% had <0 min, 41.9% had 0-59 min, 25.7% had 60-119 min and 27.7% had ≥120 min SJL. Those with ≥120 min SJL had a reduced likelihood of achieving the recommended level of LTPA (OR: 0.71, 95% CI: 0.52-0.95) and MSE (OR: 0.73, 95% CI: 0.55-0.97). In the non-linear model, an inverse U-shaped association was observed, wherein the highest probability of meeting the recommended level of LTPA and MSE was observed in those with 45 min SJL, decreasing after this threshold.

CONCLUSIONS

Individuals with ≥120 min SJL were less likely to engage in the recommended level of both aerobic and anaerobic exercise. Although future studies using a longitudinal design are required to elucidate the causal relationship between SJL and physical activity, the current findings suggest that physical inactivity during leisure time may play an important role in the increased risk of cardiometabolic abnormalities in young adults with SJL.

The Effect of Prebedtime Behaviors on Sleep Duration and Quality in Children: Protocol for a Randomized Crossover Trial

BACKGROUND

It is recommended that children should avoid eating dinner, being physically active, or using screens in the hour before bed to ensure good sleep health. However, the evidence base behind these guidelines is weak and limited to cross-sectional studies using questionnaires.

OBJECTIVE

The aim of this randomized crossover trial was to use objective measures to experimentally determine whether recommendations to improve sleep by banning electronic media, physical activity, or food intake in the hour before bed, impact sleep quantity and quality in the youth.

METHODS

After a baseline week to assess usual behavior, 72 children (10-14.9 years old) will be randomized to four conditions, which are (1) avoid all 3 behaviors, (2) use screens for at least 30 minutes, (3) be physically active for at least 30 minutes, and (4) eat a large meal, during the hour before bed on days 5 to 7 of weeks 2 to 5. Families can choose which days of the week they undertake the intervention, but they must be the same days for each intervention week. Guidance on how to undertake each intervention will be provided. Interventions will only be undertaken during the school term to avoid known changes in sleep during school holidays. Intervention adherence and shuteye latency (time from getting into bed until attempting sleep) will be measured by wearable and stationary PatrolEyes video cameras (StuntCams). Sleep (total sleep time, sleep onset, and wake after sleep onset) will be measured using actigraphy (baseline, days 5 to 7 of each intervention week). Mixed effects regression models with a random effect for participants will be used to estimate mean differences (95% CI) for conditions 2 to 4 compared with condition 1.

RESULTS

Recruitment started in March 2024, and is anticipated to finish in April 2025. Following data analysis, we expect that results will be available later in 2026.

CONCLUSIONS

Using objective measures, we will be able to establish if causal relationships exist between prebedtime behaviors and sleep in children. Such information is critical to ensure appropriate and achievable sleep guidelines.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12624000206527; https://tinyurl.com/3kcjmfnj.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/63692.

Relationship between social jetlag and body mass index in nurses working shift schedules: a cross-sectional study

This study aimed to explore the relationship between shift-working nurses' social jetlag and body mass index (BMI) and provide a theoretical basis for nursing managers to develop appropriate health interventions. Shift work is unavoidable in nursing and is associated with circadian rhythm disorders. Social jetlag is prevalent in shift-working nurses and is associated with adverse health outcomes (particularly metabolism-related indicators). BMI is a significant metabolic indicator, and research has demonstrated its effectiveness in predicting the formation of metabolic syndrome. The relationship between social jetlag and BMI can be explained by considering physiological, psychological, and behavioral factors. However, most studies on social jetlag and health status are focused on non-shift nurse populations, with fewer studies on shift workers. Five tertiary hospitals located at similar latitudes in Southwest China were selected for the study. We surveyed 429 shift-working nurses using sociodemographic data, the Munich Chronotype Questionnaire for Shift Workers, and BMI. The restricted cubic spline model was used to analyze the relationship between social jetlag and BMI among shift-working nurses, and segmented linear regression was performed around the inflection point using multiple linear regression analysis. The results revealed that social jetlag (82.0 [85.0] min) was experienced by 64.6% of the shift-working nurses. After controlling for confounding variables, the model with seven knots had the lowest accepted Akaike information criterion value, and there was a U-shaped relationship between shift-working nurses' BMI and social jetlag in this model; its inflection (lowest) point of 20.7 was considered the cut-off point. Segmented regression showed that for BMI < 20.7, BMI was significantly negative with standardized social jetlag; whereas with BMI > 20.7, BMI was significantly positive with standardized social jetlag. BMI has a U-shaped relationship with social jetlag, and attention should be paid to overweight or underweight shift-working nurses to detect early circadian rhythm disorder. Shift-working nurses with high social jetlag tended to have higher/lower BMI, which should be further investigated in the future, to minimize metabolic diseases among them.

Screen media activity in youth: A critical review of mental health and neuroscience findings

This review has two primary objectives: (1) to offer a balanced examination of recent findings on the relationship between screen media activity (SMA) in young individuals and outcomes such as sleep patterns, mood disturbances, anxiety-related concerns, and cognitive processes; and (2) to introduce a novel multi-level system model that integrates these findings, resolves contradictions in the literature, and guides future studies in examining key covariates affecting the SMA-mental health relationship. Key findings include: (1) Several meta-analyses reveal a significant association between SMA and mental health issues, particularly anxiety and depression, including specific negative effects linked to prolonged screen time; (2) substantial evidence indicates that SMA has both immediate and long-term impacts on sleep duration and quality; (3) the relationship between SMA and cognitive functioning is complex, with mixed findings showing both positive and negative associations; and (4) the multifaceted relationship between SMA and various aspects of adolescent life is influenced by a wide range of environmental and contextual factors. SMA in youth is best understood within a complex system encompassing individual, caregiver, school, peer, and environmental factors, as framed by Bronfenbrenner's ecological systems theory, which identifies five interrelated systems (microsystem, mesosystem, exosystem, macrosystem, and chronosystem) that influence development across both proximal and distal levels of the environment. This model provides a framework for future research to examine these interactions, considering moderating factors, and to develop targeted interventions that can mitigate potential adverse effects of SMA on mental well-being.