Social network analysis of group position, popularity, and sleep behaviors among U.S. adolescents

Understanding the dual role of individual position in multidimensional social support networks and depression levels: Insights from a nomination-driven framework

This study aims to investigate the relationship between the structural characteristics (e.g., single dimension friendship networks) and functional characteristics (multi-dimension) of social support networks and depressive symptoms among college students. Data were collected from 1784 students across six Chinese universities using questionnaire surveys and a nomination-based social network analysis approach. Friendship and social support networks (including four dimensions of support: appraisal, belonging, tangible, and self-esteem), were constructed to exploring relationships between network characteristics and depressive symptoms at both individual and class levels. The results indicate that greater integration and active participation in these networks are significantly linked to lower depression risks at both individual and class levels, underscoring the protective role of social connections. Yet, individuals with high betweenness centrality in networks demanding high support face increased depression risks, attributed to the stress of maintaining social cohesion and identity. Multilevel analysis further reveals that class network modularity is positively correlated with depressive symptoms and moderates the relationship between local clustering and depressive symptoms in high-burden social support networks, indicating that individuals in bridge positions or on the periphery of high-modularity networks may face increased risk of depression, potentially due to the lack of strong emotional support and social validation. These findings, by focusing on the characteristics of networks at both individual and group levels, lay a foundation for targeted intervention measures designed to optimize social support systems. They offer insights into mental health policies and practices among college students.

Social connectedness and sleep in Blackfeet American Indian adults

OBJECTIVES

A growing body of work documents a link between indices of social connectedness and sleep health. Sleep is implicated in the chronic health conditions which disproportionately affect American Indian adults, however the relationship between social connectedness and sleep health is largely understudied in this population. The current project investigates relationships between multiple indices of social connectedness and sleep health in a sample of American Indian adults.

METHODS

In a sample of 275 American Indian adults residing in the Blackfeet Nation in Montana, we investigated links between social networks, loneliness, existential isolation (i.e., feeling alone in one's experiences) and sleep health. We used one linear regression model controlling for demographics and symptoms of anxiety and depression to investigate the relationship between measures of social connectedness and sleep health.

RESULTS

Existential isolation was the only statistically significant predictors of sleep health, with higher existential isolation relating to worse sleep health.

CONCLUSION

Existential isolation may be a particularly important measure of social connectedness in American Indian adults. More research is needed to understand precursors of existential isolation and the mechanisms contributing to the relationship between existential isolation and sleep health in Blackfeet American Indian adults.

Influence of Socio-Demographic, Occupational and Lifestyle Variables on Sleep Time

Background

Socio-demographic, occupational and lifestyle variables influence total sleep time. Therefore, we aimed to evaluate the influence of those variables on sleep time, and to study risk factors of being a short sleeper.

Methods

The COVISTRESS international study is an online questionnaire using the secure REDCap® software. Total sleep time was evaluated using declared bedtime and time of awakening and was analyzed as a quantitative variable and as a qualitative variable.

Results

We included 549 respondents to the questionnaire, divided into 10-year age groups ranging from <30yo to ≥60yo. The mean quantity of sleep was 7.11±1.43 hours per night. Factors that reduce total sleep time were age (coefficient -0.19, 95CI -0.33 to 0.06), being an employee (-0.46, -0.85 to -0.06), working time (-0.18, -0.31 to 0.05), smoking ≥5 cigarettes/day (-0.5, -0.95 to -0.20), high stress at work (-0.64, -0.96 to -0.32) and at home (-0.66, -0.97 to -0.35). Being a student (0.61, 0.02 to 1.19), working less than 25h per week (0.57, 0.17 to 0.97) and telework (0.46, 0.02 to 0.89) increased total sleep time. The risk factors of being a short sleeper were age (odds ratio 1.27, 95CI 1.07 to 1.51), being an employee (2.58, 1.36 to 4.89), smoking ≥5 cigarettes/day (2.73, 1.54 to 4.84) and a high level of stress at work (2.64, 1.45 to 4.82) and at home (3.89, 2.25 to 6.63). Physical activity ≥2.5 hours/week tended to decrease the risk of being a short sleeper by 35%.

Conclusion

We demonstrated the concomitant impact of sociodemographic, occupational and lifestyle behavior on sleep, which may help to build efficient preventive strategy.

Understanding the Association Between Neighborhoods and Adolescent Sleep: Evidence from Add Health

Introduction

Research suggests that perceived neighborhood social environments (PNSE) may contribute to gender and race/ethnicity-based sleep disparities. Our study aimed to examine associations between PNSE factors and adolescents' sleep patterns. As a secondary aim, we examined how gender and race/ethnic groups might moderate these associations.

Method

Data came from the National Longitudinal Study of Adolescent to Adult Health (n=5158; mean age=15.34 years). Four self-reported sleep outcomes were created: 1) sleep duration (hours/night), 2) short sleep (≥8 hours [reference] vs <8 hours), 3) parental set bedtime (10:00 PM/earlier [reference] among girls vs by 11:00PM vs by/after 12:00AM), and 4) sleep satisfaction (enough sleep [reference] vs not enough sleep). PNSE included total scores for contentedness, social cohesion, and safety. Weighted linear and generalized logistic regressions were used to examine the relationship between each PNSE factor and sleep outcomes, adjusting for covariates. Associations were stratified by gender and race/ethnicity, separately.

Results

Neighborhood contentedness was associated with longer sleep duration and lower odds of short sleep, parental set bedtime by/after 12:00 AM, and not enough sleep. Neighborhood social cohesion was related to lower odds of a parental set bedtime by/after 12:00 AM. Neighborhood safety was related to lower odds of short sleep and not enough sleep. Gender and race/ethnic-specific results were mixed.

Conclusion

Positive perceptions of neighborhood social environments served as a protective factor against adverse sleep outcomes among adolescents. Efforts to improve adolescent sleep should consider the role of the neighborhood social context, gender, and racial and ethnic groups.

Disentangling associations between pubertal development, healthy activity behaviors, and sex in adolescent social networks

With the onset of puberty, youth begin to choose their social environments and develop health-promoting habits, making it a vital period to study social and biological factors contextually. An important question is how pubertal development and behaviors such as physical activity and sleep may be differentially linked with youths' friendships. Cross-sectional statistical network models that account for interpersonal dependence were used to estimate associations between three measures of pubertal development and youth friendships at two large US schools drawn from the National Longitudinal Study of Adolescent to Adult Health. Whole-network models suggest that friendships are more likely between youth with similar levels of pubertal development, physical activity, and sleep. Sex-stratified models suggest that girls' friendships are more likely given a similar age at menarche. Attention to similar pubertal timing within friendship groups may offer inclusive opportunities for tailored developmental puberty education in ways that reduce stigma and improve health behaviors.

Peer effects in weight-related behaviours of young people: A systematic literature review

Individual preferences and beliefs are perpetually shaped by environmental influences, with peers playing a key role in this dynamic process. Compelling evidence from qualitative and quantitative studies has highlighted the significant impact of peer influence on health-related decisions. This systematic literature review critically synthesises findings from 45 studies published between 2011 and 2022, providing a comprehensive understanding of the nature of peer effects on dietary, physical activity and sleep behaviours during youth. The majority of studies indicated that social norms drive directional changes in eating and physical activity. Yet, our analysis revealed a notable gap in exploring alternative mechanisms, including social comparison and social identity, despite their potential relevance. Studies, generally classified as moderate to high quality, predominantly relied on self-reported data, potentially affecting the validity and reliability of measures. Meta-regression analyses suggest a small, but significant association of sample size with the magnitude, sign and significance of the reported peer effects. Moreover, studies focusing on physical activity are more likely to report significant outcomes, whereas findings on peer influence on sleep-related studies tend to reveal less pronounced effects, compared to studies on dietary behaviours. Experimental designs do not appear to increase the likelihood of finding significant effects when compared to other study designs. In conclusion, this synthesis emphasises the need for further research into the underlying mechanisms on peer effects to better inform policy-makers in designing effective policies for improving weight-related behaviours in young people.

A Prospective Sociocentric Study of 2 Entire Traditional Korean Villages: The Korean Social Life, Health, and Aging Project (KSHAP)

The Korean Social Life, Health, and Aging Project (KSHAP) was a multidisciplinary prospective study conducted in South Korea that measured various health biomarkers from blood, hair, and brain magnetic resonance imaging, and we examined their associations with sociocentric (global) social network data of older adults in 2 entire villages (or cohorts). Cohort K included participants aged 60 years or older, and cohort L included participants aged 65 years or older. We performed a baseline survey involving 814 of the 860 individuals (94.7% response rate) in cohort K in 2012 and 947 of the 1,043 individuals (90.8% response rate) in cohort L in 2017. We gathered longitudinal data for 5 waves in cohort K from 2011 to 2019 and 2 waves in cohort L from 2017 to 2022. Here, we describe for the first time the follow-up design of the KSHAP, the changes in social networks, and various biomarkers over a number of years. The data for cohort K are publicly available via the Korean Social Science Data Archive as well as the project website, and the data for cohort L will be shared soon.

Adverse childhood experience and persistent insomnia during emerging adulthood: do positive childhood experiences matter?

BACKGROUND

Adverse childhood experiences (ACE) have been documented to have long-term impacts on sleep disturbances. However, less is known about how ACE co-occurs with positive childhood experiences (PCE) and modulate their effects on adult sleep disturbances, particularly in the context of persistent insomnia. Building on resilience theory, this study aims to examine the interplay between ACE and PCE and their effects on persistent insomnia during emerging adulthood.

METHODS

A total of 2,841 emerging adults were recruited from the Taiwan Youth Project. Persistent insomnia during emerging adulthood was assessed using two adult surveys (mean age = 19.8 and 21.9). The ACE (10 items) and PCE (7 items) were obtained from the baseline survey (mean age = 13.8). A series of logistic regression analyses were conducted.

RESULTS

Among the emerging adults, 29.22% had persistent insomnia. Consistent with the compensatory model, ACE and PCE exerted opposing effects on persistent insomnia during emerging adulthood. In line with the protective model, the negative effect of ACE is mitigated when individuals have high PCE. However, consistent with the challenge model, the protective effect of PCE on persistent insomnia was inhibited in individuals with four or more ACE.

CONCLUSIONS

PCE serves as a protective factor, shielding emerging adults from the adverse effects of ACE on persistent insomnia. It is essential to prioritize positive experiences during early life to promote lifelong sleep health.

The association between adverse childhood experiences and insomnia symptoms from adolescence to adulthood: Evidence from the Add Health study

OBJECTIVES

Adverse childhood experiences are potentially traumatic events that occur up to age 17, including abuse, neglect, and household dysfunction. Such trauma often results in chronic stress and poor sleep health, which are linked to negative health outcomes across the lifespan. This study examines the longitudinal association between adverse childhood experiences (ACEs) and insomnia symptoms from adolescence to adulthood.

METHODS

Data from the National Longitudinal Study of Adolescent to Adult Health were used to examine the association between ACEs and insomnia symptoms (trouble falling asleep or staying asleep, dichotomized based on self-reported frequency of 3 times per week or more). We used weighted logistic regression to examine the association between cumulative ACE score (0, 1, 2-3, 4+), 10 specific ACEs, and insomnia symptoms.

RESULTS

Of 12,039 participants, 75.3% experienced at least one adverse childhood experience and 14.7% experienced 4 or more. We found specific adverse childhood experiences, including physical abuse, emotional abuse, neglect, parental incarceration, parental alcoholism, foster home placement, and community violence were associated with experiencing insomnia symptoms throughout the entire 22-year follow-up period from adolescence to mid-adulthood (p < .05), while childhood poverty was only associated with insomnia symptoms in mid-adulthood. The number of adverse childhood experiences showed a dose-response association with insomnia symptoms in adolescence (1 adverse childhood experience: adjusted odds ratio (aOR)=1.47 [1.16, 1.87], 4+ adverse childhood experiences: aOR= 2.76, [2.18, 3.50]), early adulthood (1 adverse childhood experience: aOR= 1.43 [1.16, 1.75], 4+ adverse childhood experiences: aOR= 3.07 [2.47, 3.83]) and mid-adulthood (1 adverse childhood experience: aOR= 1.13 [0.94, 1.37], 4+ adverse childhood experiences: aOR= 1.89 [confidence interval: 1.53, 2.32]).

CONCLUSIONS

Adverse childhood experiences are associated with an increased risk for insomnia symptoms across the lifespan.

Association of Peer Network with Childhood Obesity in DECIDE-Children Program

Some studies have found associations between the peer network and childhood obesity. The present study aimed to analyze the association of the peer network with obesity-related cognition, behaviors and adiposity indicators, and explore whether peer network influences the effect of a childhood-obesity intervention. Based on DECIDE-Children, 1392 children's friendship nominations within the class were collected and peer network indicators including the network size, network density, and in- and out-degree centrality were calculated. The linear mixed model was used to analyze the association between peer network indicators and children's cognition, behaviors and adiposity indicators (body mass index (BMI), BMI z score, the prevalence of overweight and obesity). Children with a higher in-degree centrality had 34.4% (95%CI: 17.4% to 48.1%) lower risk of overweight or obesity. The baseline degree centrality was inversely associated with the BMI and BMI z score at the end of the trial. For each unit increase in in-degree centrality at baseline, the BMI at the end of the trial decreased by 0.047 (95%CI: 0.015 to 0.080), and the BMI z score decreased by 0.015 (95%CI: 0.003 to 0.028). Children's popularity reflected by centrality in their peer network was associated with cognition, behaviors, and adiposity indicators. Future childhood-obesity intervention research could pay more attention to socially inactive children.

Adolescent relational behaviour and the obesity pandemic: A descriptive study applying social network analysis and machine learning techniques

AIM

To study the existence of subgroups by exploring the similarities between the attributes of the nodes of the groups, in relation to diet and gender and, to analyse the connectivity between groups based on aspects of similarities between them through SNA and artificial intelligence techniques.

METHODS

235 students from 5 different educational centres participate in this study between March and December 2015. Data analysis carried out is divided into two blocks: social network analysis and unsupervised machine learning techniques. As for the social network analysis, the Girvan-Newman technique was applied to find the best number of cohesive groups within each of the friendship networks of the different classes analysed.

RESULTS

After applying Girvan-Newman in the three classes, the best division into clusters was respectively 2 for classroom A, 7 for classroom B and 6 for classroom C. There are significant differences between the groups and the gender and diet variables. After applying K-means using population diet as an input variable, a K-means clustering of 2 clusters for class A, 3 clusters for class B and 3 clusters for class C is obtained.

CONCLUSION

Adolescents form subgroups within their classrooms. Subgroup cohesion is defined by the fact that nodes share similarities in aspects that influence obesity, they share attributes related to food quality and gender. The concept of homophily, related to SNA, justifies our results. Artificial intelligence techniques together with the application of the Girvan-Newman provide robustness to the structural analysis of similarities and cohesion between subgroups.

To Make and Keep Friends: The Role of Health Status in Adolescent Network Tie Formation and Persistence

Health status may shape network structure through network dynamics (tie formation and persistence) and direction (sent and received ties), net of typical network processes. We apply Separable Temporal Exponential Random Graph Models (STERGMs) to National Longitudinal Study of Adolescent to Adult Health survey data (n = 1,779) to differentiate how health status shapes network sent and received tie formation and persistence. Results indicate that networks are shaped by withdrawal of adolescents experiencing poor health, highlighting the importance of separating distinct and directed processes of friendship formation and persistence when considering how health relates to adolescent social life.

Leadership and contagion by COVID-19 among residence hall students: A social network analysis approach

University students have changed their behaviour due to the COVID-19 pandemic. In this paper, we describe the characteristics of PCR+ and PCR- nodes, analyse the structure, and relate the structure of student leaders to pandemic contagion as determined by PCR+ in 93 residential university students. Leadership comes from the male students of social science degrees who have PCR +, with an eigenvector centrality structure, β-centrality, and who are part of the bow-tie structure. There was a significant difference in β-centrality between leaders and non-leaders and in β-centrality between PCR+ and non-leaders. Leading nodes were part of the bow-tie structure. MR-QAP results show how residence and scientific branch were the most important factors in network formation. Therefore, university leaders should consider influential leaders, as they are vectors for disseminating both positive and negative outcomes.

The Role of Adverse Childhood Experiences in Multidimensional Nature of Subjective Age

OBJECTIVES

Age stereotypes and expectations about one's own aging commence in childhood, while most research focuses on predictive associations with midlife cognition and health outcomes in later life. This study instead aims to examine adverse childhood experiences (ACEs) contributing to multiple measures of subjective age (SA) among Chinese older adults and test whether these relationships differ by household registration (hukou).

METHODS

In a representative sample of Chinese older adults aged 60 and older from the 2018 China Longitudinal Aging and Social Survey (n = 7,815), ordinary least squares is used to examine the associations between ACEs and 3 facets of SA: felt age, look age, and self-defined aging standard.

RESULTS

Childhood starvation experience and limited health care access predict older felt age and look age, while parental death is associated with lower self-defined aging standard. Zooming in on hukou-specific associations shows that the dose-response relationship on older adults with rural hukou is particularly pronounced.

DISCUSSION

Findings provide empirical support for views of aging from a life-course perspective and highlight the enduring impact of ACEs for late-adulthood SA, as well as their differential influence on multiple indicators of SA. Interventions that focus on promoting health and development in childhood could potentially have effects beyond the childhood phase, and benefit for their positive aging attitude in later life.

The Social Side of Sleep: A Systematic Review of the Longitudinal Associations between Peer Relationships and Sleep Quality

In adolescence, peer relationships become crucial since youths start to rely on their peers for support. Thus, multiple facets of adolescents' well-being are affected by their peer relationships. In this vein, one of the central well-being aspects that could be affected by the peer relationships of adolescents is sleep quality. Nevertheless, it is still unclear how multiple peer relationship factors (i.e., positive, negative, emotional, and behavioral issues related to peer relationships) are intertwined with adolescents' sleep quality. For this reason, this systematic review with meta-analysis aims to summarize longitudinal studies to uncover how the interplay between peer relationship factors and adolescents' sleep quality unfolds over time. Nineteen longitudinal studies involving a total of 21,232 adolescents were included. Overall, findings from this review showed that (a) positive peer relationships and sleep quality were not associated over time; (b) negative peer relationships and sleep quality were bidirectionally associated over time; (c) few studies evaluated the bidirectional relations between emotional and behavioral issues and sleep quality, showing links with sleep schedule and duration, but not with sleep quality. Meta-analytic results were discussed, considering their implications.

Adolescent sleep quality and quantity and educational attainment: a test of multiple mechanisms using sibling difference models

OBJECTIVE

The objective of this study is to determine whether and how sleep quality and quantity during adolescence are related to educational attainment in adulthood. This study also investigates whether this relationship varies by gender.

METHODS

Using data from the National Longitudinal Study of Adolescent to Adult Health, the present study employed a sibling fixed effect approach that takes into account unobserved family background factors such as genetics and social environments. Gender-stratified analyses were conducted to consider the potential gendered relationship between adolescent sleep and educational attainment.

RESULTS

Controlling for unobserved family-level heterogeneity attenuated the associations between adolescent sleep characteristics and educational attainment, albeit in different ways for boys and girls. Gender-stratified models suggest that, for boys, only the association between short sleep duration and educational attainment was robust to adjustment for sibling fixed effects. In contrast, for girls, among three sleep quality measures, only trouble falling or staying asleep remained significantly associated with educational attainment even after controlling for unobserved family heterogeneity. Sibling fixed effects estimates suggest that short sleep duration (6 or fewer hours per night) was negatively associated with years of schooling only among boys (b = -0.443), whereas trouble falling or staying asleep was associated with a reduction in years of schooling only among girls (b = -0.556). The mechanisms underlying the observed associations also differed by gender. For boys, the association between short sleep duration and educational attainment was partially explained by a combination of educational, social, and psychological factors. Only intermediate educational factors explained part of the association between trouble falling or staying asleep and educational attachment among girls.

CONCLUSIONS

The study's finding that the relationship between adolescent sleep characteristics and educational attainment and the mechanisms underlying this relationship differ by gender calls attention to the need for gender-specific interventions.

Daily Experiences of Discrimination and Ethnic/Racial Minority Adolescents' Sleep: The Moderating Role of Social Support

Using data from a 14-day diary study of 95 ethnic/racial minority adolescents, this study examined the within-person effect of daily discrimination tied to multiple social identities on adolescents' daily sleep quality and duration and whether daily support from important others (i.e., friends, parents, and teachers) would moderate these links. We found that daily discrimination was a low-frequency, but high-impact event associated with shorter sleep duration. Results pointed to the nuanced roles of daily support. Support from friends was negatively related to sleep duration, whereas support from parents appeared to be promotive to sleep quality. Support from teachers protected adolescents from the negative effects of discrimination on sleep duration. Implications for future interventions targeting sleep disturbances associated with discrimination are discussed.

Sleepy and Secluded: Sleep Disturbances are Associated With Connectedness in Early Adolescent Social Networks

Studies in adults suggest that sleep disturbances predict poorer socioemotional skills and impaired social interactions. However, little is known regarding how sleep disturbances are associated with social processes during adolescence, a period when both sleep neurobiology and social relationships are undergoing dramatic developmental changes. The current study examined associations among sleep disturbances and peer connectedness in a sample of middle-school students (N = 213, 11-15 years old, 57% female) using a social network approach. Findings suggested that youth with greater sleep disturbances reported having fewer social connections, were rated as a social connection by fewer peers, and were less likely to have reciprocated nominations, even after controlling for sociodemographic characteristics and mental health symptoms.

Identification of cohesive subgroups in a university hall of residence during the COVID-19 pandemic using a social network analysis approach

THE AIMS

(i) analyze connectivity between subgroups of university students, (ii) assess which bridges of relational contacts are essential for connecting or disconnecting subgroups and (iii) to explore the similarities between the attributes of the subgroup nodes in relation to the pandemic context. During the COVID-19 pandemic, young university students have experienced significant changes in their relationships, especially in the halls of residence. Previous research has shown the importance of relationship structure in contagion processes. However, there is a lack of studies in the university setting, where students live closely together. The case study methodology was applied to carry out a descriptive study. The participation consisted of 43 university students living in the same hall of residence. Social network analysis has been applied for data analysis. Factions and Girvan-Newman algorithms have been applied to detect the existing cohesive subgroups. The UCINET tool was used for the calculation of the SNA measure. A visualization of the global network will be carried out using Gephi software. After applying the Girvan-Newman and Factions, in both cases it was found that the best division into subgroups was the one that divided the network into 4 subgroups. There is high degree of cohesion within the subgroups and a low cohesion between them. The relationship between subgroup membership and gender was significant. The degree of COVID-19 infection is related to the degree of clustering between the students. College students form subgroups in their residence. Social network analysis facilitates an understanding of structural behavior during the pandemic. The study provides evidence on the importance of gender, race and the building where they live in creating network structures that favor, or not, contagion during a pandemic.

Being Popular or Having Popular Friends, Which Is Better? A Longitudinal Social Network Analysis of Depressive Symptoms among Chinese Adolescents under Major Chronic Stress

Background: Previous studies have found that adolescents’ depressive symptoms are influenced by social networks in a stressful context, especially focusing on the processes of social selection and social influence. The current study aimed to explore the coevolution of sociometric popularity and depressive symptoms among adolescents suffering from the stress attached to the Chinese gaokao. Methods: The analytical sample comprised 1062 Chinese adolescents who were under significant pressure to return to school for an additional year (returnees) to prepare for college entrance examinations. Students were assessed for depressive symptoms and asked to nominate up to five friends within their classes across four waves (six months). We employed stochastic actor-oriented models to investigate the interdependent relationships between popularity and depressive symptoms. Results: Adolescents’ depressive symptoms negatively predicted future friendship popularity in this stressful situation, but not vice versa. The results of this study also highlighted the importance of friends’ popularity, indicating that adolescents who nominated popular peers as friends tended to subsequently have lower depressive symptoms. Conclusion: These findings suggested that friends’ popularity may serve as a protective factor against depressive symptoms under major chronic stress. Network-based interventions may have practical implications for reducing depressive symptoms under major chronic stress.

The Human Sleep Paradox: The Unexpected Sleeping Habits of Homo sapiens

The human sleep pattern is paradoxical. Sleep is vital for optimal physical and cognitive performance, yet humans sleep the least of all primates. In addition, consolidated and continuous monophasic sleep is evidently advantageous, yet emerging comparative data sets from small-scale societies show that the phasing of the human pattern of sleep–wake activity is highly variable and characterized by significant nighttime activity. To reconcile these phenomena, the social sleep hypothesis proposes that extant traits of human sleep emerged because of social and technological niche construction. Specifically, sleep sites function as a type of social shelter by way of an extended structure of social groups that increases fitness. Short, high-quality, and flexibly timed sleep likely originated as a response to predation risks while sleeping terrestrially. This practice may have been a necessary preadaptation for migration out of Africa and for survival in ecological niches that penetrate latitudes with the greatest seasonal variation in light and temperature on the planet.

Friendship and Consumption Networks in Adolescents and Their Relationship to Stress and Cannabis Use Intention

Background: Cannabis is an illegal psychoactive substance that’s use is widespread among adolescents. During adolescence, many changes can cause stress. In this phase, the group of friends becomes increasingly important, being a situation of vulnerability for the beginning of cannabis use, either as an escape mechanism or due to peer’s influence. Therefore, the purpose of this study is to describe and analyze the structure of the consumption and friendship network, the intention to use cannabis, and the stress in a secondary school class. Methods: An online platform with validated self-reported questionnaires were used for data collection. Results: The sample consisted of adolescents (n = 20) aged 14–16 from a third-year class of compulsory secondary education in Ponferrada (León, Spain). Significant differences were obtained concerning consumption intention and the different network metrics in both the friendship and consumption networks. Subsequently, the representation of these networks was carried out. Conclusions: Social Network Analysis is a very useful tool that provides a picture of the context in which adolescents are located. In the consumption network, there are central actors who have not yet consumed cannabis; this is a crucial moment to implement prevention strategies.

Realfooders Influencers on Instagram: From Followers to Consumers

(1) Background: Realfooders have positioned themselves in social networks such as Instagram by posting photographs of recipes, advises, habits and nutritional behaviours which are advertised as reliable nutritional patterns and by their self-promotion as highly trained people in the field of nutrition which sometimes jeopardises the health of digital citizenry. (2) Methods: In this article, we develop a quantitative study for analysing the influence of selected Realfooders on 2,866,980 followers on Instagram, taking into account channel variables (gender, location, interests and motivations), followers’ variables (engagement, interaction and consumption) and some variables related to the message of 54 posts about breakfast. (3) Results: Selected Realfooders concentrate their followers in Spain, mostly women between 18 and 24 and between 35 and 44 years old who link their interests on food to the cult of the body and recreational areas. On the other hand, the content generated by Realfooders has been increasing its impact using advertising and marketing techniques for awaking consumer’s interest. (4) Conclusions: Educational and social agents are facing the challenge of low health literacy in young population. Therefore, it is necessary to design and implement strategies for developing critical thinking that allow them to assess the content generated by Realfooders and identify which recommendations can be harmful or beneficial to their health.

Sleep and social relationships in healthy populations: A systematic review

Over the past decade, research linking sleep and social relationships has burgeoned. Researchers across the globe are trying to understand whether the quality and quantity of our social relationships matter for sleep, and vice versa. We conducted a systematic review of the literature, identifying over 200 relevant articles examining sleep and social relationships in healthy populations. Here, we summarize our findings by reviewing 1) links between sleep and broad social ties across the lifespan, and 2) links between sleep and specific social relationships identified in the literature search, including romantic relationships, family relationships, and work relationships. Taken together, the literature provides evidence that the quality and presence of social relationships, especially our closest relationships, play a role in how we sleep. Likewise, sleep appears to influence our social bonds. However, the majority of work is correlational, limiting conclusions about the directionality of these effects. We conclude by synthesizing the findings, considering the limitations of the present literature, and identifying key future directions for this emerging area of research.

Taking the sleep lab to the field: Biometric techniques for quantifying sleep and circadian rhythms in humans

OBJECTIVES

Remarkably, the specifics of sleep along the human lineage have been slow to emerge, which is surprising given our distinct mental and behavioral capacity and the importance of sleep for individual health and cognitive performance. Largely due to difficultly of measuring sleep outside a controlled, clinical, and laboratory study in ambulatory individuals, human biologists have yet to undergo a thorough examination of sleep in ecologically diverse settings. Here, I outline the procedures and methods for generating sleep data in a broader ecological context with the goal of facilitating the integration of sleep and circadian analyses into human biology research.

METHODS

I describe the steps involved in participant recruitment, screening by way of survey instruments, and sample collection. In addition to describing field use of the traditional (but invasive) equipment such as the gold-standard application of electroencephalography (EEG), I demonstrate leading-edge noninvasive techniques for biometric devices (ie, wrist-worn actigraphy, ring worn arterial pulsometry) to generate sleep and circadian rhythms data.

RESULTS

I outline best approaches to process and analyze data-including variables such as sleep duration, 24-hour sleep time (ie, summation of night and day sleep), sleep efficiency, sleep fragmentation, and nonparametric circadian rhythms analysis to quantify circadian amplitude. Finally, I discuss comparative statistical methods that are optimized for the use of time-series data.

CONCLUSIONS

This review serves as an introduction to the best practices for studying sleep-wake patterns in humans-with the goal of standardizing tools for launching new human sleep biology research initiatives across the globe.

Childhood Friendship Experiences and Cognitive Functioning in Later Life: The Mediating Roles of Adult Social Disconnectedness and Adult Loneliness

BACKGROUND AND OBJECTIVES

This study investigated the relationship between childhood friendships and cognitive functioning, as assessed with cognitive status and decline among adults aged 45 and older in China. We also examined the mediating effect of adult social disconnectedness and adult loneliness for this relationship.

RESEARCH DESIGN AND METHODS

This study was based on 3 waves of data from the China Health and Retirement Longitudinal Study (CHARLS; 2011, 2013, 2015; N = 13,959). Cognitive functioning was assessed with episodic memory. Childhood friendship measures were taken from the 2014 life history module of the CHARLS. Two dimensions of adult social isolation, loneliness and social disconnectedness, were included as mediators. Latent growth curve modeling was utilized to test the associations between childhood friendships, adult social isolation, and cognitive functioning.

RESULTS

Adverse childhood friendship experiences were found to be significantly associated with both lower initial cognitive status and the rate of decline in cognitive functioning. Our findings indicated that adult loneliness and social disconnectedness partly mediated the link between childhood friendship experiences and the initial level of cognitive functioning, but not cognitive decline later in life.

DISCUSSION AND IMPLICATIONS

The findings emphasized the enduring importance of childhood friendships for cognitive functioning later in life. Interventions that focus on improving social participation through fostering friendships in childhood may have long-term benefits for cognition later in life.

Smoking behavior prevalence in one's personal social network and peer's popularity: A population-based study of middle-aged adults in Japan

Although previous social network studies have consistently shown the social influence of peers' smoking on one's (ego's) smoking, few studies have examined how the influence differs according to peers' structural positions in the network. Investigations are also lacking on whether vulnerability to the influence varies by ego's socioeconomic position. Thus, the present study aimed to examine how the association between peers' smoking and ego's smoking differs by peers' popularity in ego's personal network and ego's educational attainment. We used data from the third-wave Japanese Study on Stratification, Health, Income, and Neighborhood (J-SHINE) conducted in 2017, which targeted middle-aged (32-58-year-old) residents in four municipalities within Japanese metropolitan areas. Information on four close peers' characteristics and behaviors and their mutual relationships was collected by the name generator and name interpreter methods. Data on 1989 respondents and 7956 peers were evaluated. Peers' eigenvector centrality was used as their popularity index in ego's personal network. We set ego's smoking as an outcome, regressed on each peer's smoking, each peer's popularity, and ego's educational attainment adjusting for ego's age, sex, working status, marital status, spouse's/partner's smoking status, as well as similarity in socioeconomic backgrounds between peer and ego, using a logistic regression model with robust standard errors. We then added a three-way interaction term for these three explanatory variables to the model. Results showed that peer's smoking status was related to ego's smoking even more strongly when the peer was popular but only in the case of ego with lower educational attainment. The results suggested that the disparity in smoking behavior across socioeconomic positions may be partly explained by susceptibility to social influence from one's personal network among the socioeconomically vulnerable. This study proposes a plausible method for pinpointing the peer influencer in one's personal social network to close the socioeconomic gap in smoking.