From Lark to Owl: developmental changes in morningness-eveningness from new-borns to early adulthood

Sleep deprivation in development of obesity, effects on appetite regulation, energy metabolism, and dietary choices

Sleep deprivation, which is a decrease in duration and quality of sleep, is a common problem in today's life. Epidemiological and interventional investigations have suggested a link between sleep deprivation and overweight/obesity. Sleep deprivation affects homeostatic and non-homoeostatic regulation of appetite, with the food reward system playing a dominant role. Factors such as sex and weight status affect this regulation; men and individuals with excess weight seem to be more sensitive to reward-driven and hedonistic regulation of food intake. Sleep deprivation may also affect weight through affecting physical activity and energy expenditure. In addition, sleep deprivation influences food selection and eating behaviours, which are mainly managed by the food reward system. Sleep-deprived individuals mostly crave for palatable energy-dense foods and have low desire for fruit and vegetables. Consumption of meals may not change but energy intake from snacks increases. The individuals have more desire for snacks with high sugar and saturated fat content. The relationship between sleep and the diet is mutual, implying that diet and eating behaviours also affect sleep duration and quality. Consuming healthy diets containing fruit and vegetables and food sources of protein and unsaturated fats and low quantities of saturated fat and sugar may be used as a diet strategy to improve sleep. Since the effects of sleep deficiency differ between animals and humans, only evidence from human subject studies has been included, controversies are discussed and the need for future investigations is highlighted.

Examining Health Behaviors as Mechanisms Linking Earlier Pubertal Timing with Accelerated Epigenetic Aging in Late Adolescence

Earlier pubertal timing is associated with accelerated epigenetic aging, but the underlying mechanisms are not well understood. This three-wave longitudinal study examined negative health behaviors, specifically substance use, short sleep duration, and poor diet quality in middle adolescence, as mediators of links between earlier phenotypic and perceived pubertal timing measured in early adolescence and epigenetic aging on three epigenetic clocks in late adolescence (GrimAge, DunedinPACE, and PhenoAge). Phenotypic pubertal timing measured physical pubertal maturation relative to chronological age, whereas perceived pubertal timing was based on adolescents' subjective interpretation of their pubertal timing relative to their peers. Participants included 1213 youth (51% female, 49% male; 62% Black, 34% White) who participated during early adolescence (mean age = 13.10 years), middle adolescence (mean age = 16.1 years) and late adolescence (mean age = 19.7 years). Results from a mediation model revealed a mediation effect of earlier phenotypic pubertal timing on accelerated GrimAge in late adolescence through higher substance use during middle adolescence. There was also a direct effect of earlier phenotypic pubertal timing on accelerated DunedinPACE in males. Sleep duration and diet quality did not emerge as mediators but shorter sleep duration predicted accelerated GrimAge in females. These findings suggest that higher substance use presents a mechanism through which earlier maturing youth experience faster epigenetic aging that puts them at risk for poorer health across the lifespan.

Transdiagnostic Sleep and Circadian Intervention in Youth: Long-Term Follow-Up of a Randomized Controlled Trial

OBJECTIVE

This preregistered study compared the effects of the Transdiagnostic Sleep and Circadian Intervention (TranS-C) with psychoeducation (PE) about sleep, health, yoga, meditation, and outdoor appreciation activities on sleep and circadian functioning, health risk, and sleep health behaviors at long-term follow-up (LTFU), an average of 8 years following treatment. We also examined if more sleep health behaviors at LTFU were associated with better sleep and circadian functioning at LTFU and if better sleep and circadian functioning were associated with lower health risk at LTFU.

METHOD

At baseline, we randomly assigned adolescents with an eveningness chronotype to TranS-C (n = 89) or PE (n = 87). Of this sample, we assessed 106 young adults (mean age at follow-up = 22.5 years; n = 55 from TranS-C; n = 51 from PE) an average of 8 years following treatment.

RESULTS

Despite TranS-C (vs PE) sustaining improvement in circadian functioning through 12-month follow-up, at LTFU, there were no significant differences between the conditions on any outcome, including sleep and circadian functioning, risks in 5 health domains indexed by self-report and ecological momentary assessment, sleep health behaviors, and physical measurements. Across both conditions, measures indicating poorer sleep and circadian functioning were associated with higher health risk across multiple domains, and more sleep health behaviors were associated with lower levels of eveningness at LTFU.

CONCLUSION

These results provide an important window into the influence of development on long-term outcomes for youth and raise the possibility that interventions for youth could be enhanced with a focus on habit formation.

PLAIN LANGUAGE SUMMARY

This study evaluated the effects of a psychological treatment (the Transdiagnostic Sleep and Circadian Intervention [TranS-C]), relative to a psychoeducation active control (PE) at 8 years following treatment, on sleep problems, the preference and tendency for later bedtimes and health risk (ie, risk for worse health). Across both groups combined, the study also examined whether more sleep health behaviors are related to better sleep and whether better sleep is related to lower health risk. At long-term follow-up, there were no differences between TranS-C and PE on any outcome. However, overall poorer sleep was related to greater health risk, and those who engaged in better sleep habits tended to have an earlier "feeling best" sleep rhythm at long-term follow-up. Given evidence that youth tend to outgrow their preference and tendency for later bedtimes with age, our findings shed light on the potential impact of development on long-term outcomes for youth and raise the question of whether treatments for youth could be improved with evidence-based tools for promoting habit formation of positive sleep behaviors.

CLINICAL TRIAL REGISTRATION INFORMATION

Maintaining Behavior Change: A 6-Year Follow-up of Adolescent 'Night-owls'; https://www.

CLINICALTRIALS

gov/; NCT05098782.

STUDY PREREGISTRATION INFORMATION

Long-term Follow-up of Young Adults Who Received TranS-C to Modify Eveningness Chronotype in Adolescence; https://osf.io/; d5a4g.

DIVERSITY & INCLUSION STATEMENT

We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. We worked to ensure sex and gender balance in the recruitment of human participants. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science. One or more of the authors of this paper self-identifies as living with a disability. One or more of the authors of this paper received support from a program designed to increase minority representation in science.

The impact of idiopathic hypersomnia on the social lives of young adults

OBJECTIVES

People with idiopathic hypersomnia report significant impairment in their lives due to idiopathic hypersomnia symptoms, and this likely includes an impact on social relationship health. This study investigated the effects of idiopathic hypersomnia on social relationships (friends, romantic, and sexual) during the key developmental period of young adulthood.

METHODS

Young adults (N = 106; 18-39years) with idiopathic hypersomnia were recruited through national hypersomnia patient organizations. Participants completed an online survey assessing the impact of symptoms on overall social functioning, as well as assessing friendships, romantic relationships, and sexual relationships.

RESULTS

Nearly all participants (98%) reported that idiopathic hypersomnia made their social life more challenging. Over half (56%) felt they had too few close friends. While 69% were currently in a romantic relationship, the majority (92%) reported that idiopathic hypersomnia made it more challenging to enter a romantic relationship, with 89% stating that it impacted their sex life. Symptoms with the greatest perceived impact on social relationships were excessive sleepiness, brain fog, and long sleep. Most participants expressed that they would like their clinicians to ask about their social lives.

CONCLUSIONS

Idiopathic hypersomnia substantially impacts the social lives of young adults, including friendships, romantic partnerships, and sex lives. Despite the importance of social relationships, clinicians seldom address this topic during clinic visits. When considering whole person health for people with idiopathic hypersomnia, clinical care would benefit from more attention to social health.

The association of chronotype, sleep duration and trajectories of health-risk behaviors among college students: a cohort study

PURPOSE

To describe the trajectories of health-risk behaviors (HRBs) among college students through four consecutive surveys and explore the relationship between chronotype, sleep duration and different trajectories of HRBs.

METHODS

We used a data sample of 1,042 college students from the College Student Behavior and Health Cohort Study. Students reported sleep parameters, including chronotype (Morningness-Eveningness Questionnaire-5, MEQ-5) and sleep duration. The behavior scale was used to evaluate four HRBs (smoking, alcohol use, low physical activity, smartphone addiction). The latent class growth analysis (LCGA) was used to estimate the trajectory of self-reported HRBs. Multivariate logistic regression models were used to study whether sleep parameters (chronotype and sleep duration) correlated with HRBs' trajectories.

RESULTS

Four unique trajectories of behaviors were identified: unhealthy group (7.4%), increasing group (21.3%), decreasing group (10.3%) and healthy group (61.0%). Compared with the normal sleep, results from logistic regression analyses indicated that long sleep (> 9 h) was associated with the decreasing group and the unhealthy group (P < 0.05), while short sleep (< 7 h) was associated with the increasing group and the unhealthy group (P < 0.05). Compared with the M-type, the E-type were positively correlated with the unhealthy group, the increasing group, and the decreasing group (P < 0.05).

CONCLUSION

E-type, short sleep duration and long sleep duration were significantly associated with the trajectory of HRBs. Findings underscore the need for targeted screening and prevention of modifiable sleep behaviors with the aim of improving HRBs in college students.

Examining sex differences in morningness-eveningness and inter-individual variability across years of age: A cross-sectional study

This study investigated the impact of age on morningness-eveningness (ME) and its inter-individual variability, with a focus on sex-specific patterns. A sample of 2890 participants aged 12-94 years (55.85% female) completed the Composite Scale of Morningness. Multiple linear regression analyses revealed a significant Age × Sex interaction, indicating distinct age-dependent patterns for males and females in both ME and its inter-individual variability. We conducted segmented regression analyses to explore these dynamics further and identify breakpoints. Eveningness increased across adolescence, with both males and females reaching peak lateness at 20 years. Morningness increased thereafter until 64.94 years for females and until 59 years for males. Following these sex-specific breakpoints, morningness remained constant for females and increased at a reduced rate for males. After the age of 48, males exhibited greater morningness than females. Inter-individual variability in ME (VME) changed with age, increasing until 33 years for men and 36.80 years for women, followed by a decrease for both sexes. From 50.30 years onward, females showed greater VME compared to men. This study suggests that ME and VME shift across age, and differences between sexes were observed from middle age onwards. Diurnal preferences are likely influenced by internal and environmental variables.

Insomnia in adolescent epidemiological studies: To what extent can the symptoms be explained by circadian factors?

Epidemiological studies show a high prevalence of "insomnia" in adolescents. However, insomnia symptoms are not specific for insomnia disorder. Puberty is associated with circadian delay, which may cause insomnia symptoms such as problems falling asleep and daytime impairments, but also difficulties rising in the morning which is not a hallmark of insomnia disorder. The aim of this study was to investigate the extent to which adolescent insomnia symptoms may be attributed to circadian delay. The sample comprised 3,867 high-school-students. Survey instruments included the Bergen Insomnia Scale (BIS), the Munich ChronoType Questionnaire (MCTQ), the reduced Morningness-Eveningness Questionnaire (r-MEQ), and items on subjective sleep problems and sleep-related behaviors. Symptoms of circadian delay (CD) were defined as i) trouble waking on school days, ii) ability to sleep long into the day, iii) waking ≥10:00 on free days and/or iv) oversleeping for school. A total of 34.5% reported insomnia according to BIS. Among these, 88.4% reported ≥1 CD-symptom and 15.5% reported all CD-symptoms. Adolescents with insomnia and ≥1 CD-symptom were often evening-types (56.9%), had long social jetlag (2:55 h) and large school-/free day discrepancy in sleep duration (6:04 vs. 8:34 h). Results suggest circadian delay as a plausible explanation for insomnia symptoms in many adolescents.

The Role of Timing and Amount of Outdoor Play in Emotional Dysregulation in Preschool Children

BACKGROUND

Currently, the time children spend playing outdoors is at an all-time low. However, the existing literature suggests that outdoor play may have cognitive and emotional benefits for children.

METHODS

The present study carried out a mediation analysis to explore whether amount and timing of outdoor play affects children's emotion regulation and whether working memory mediates these relations among 325 preschool children (Mage = 4.19, SD = 0.85) residing in a large Midwestern city in the United States.

RESULTS

Results showed that greater amounts of outdoor play very early (i.e., wake-up to noon) and very late (i.e., 6 PM to bedtime) in the day were related to greater emotional dysregulation. By contrast, greater amount of outdoor play from noon to 6 PM was related to lower emotional dysregulation. Importantly, the effect of amount of outdoor play from noon to 6 PM on emotion regulation was fully mediated by working memory.

CONCLUSION

The findings of the present study suggest that in early childhood outdoor play that supports children's circadian rhythms may have cognitive and, in turn, emotional benefits.

Associations among chronotype and eating habits in adolescents are affected by study shift: A cross-sectional study

We investigated the influence of chronotype on eating habits among adolescents attending schools with morning (07:00 hours-12:00 hours) or afternoon (13:00 hours-18:00 hours) shifts, hypothesizing that incompatibility of study schedules may be related to dietary choices. In this cross-sectional study, 734 adolescents (aged 14-19 years) completed an online questionnaire covering eating habits, chronotype, sleep duration, social jet lag, socioeconomic data, physical activity and anthropometric measures. Odds ratios with 95% confidence intervals were estimated using adjusted logistic regression, stratified by study shift. In the morning shift, a morning chronotype was associated with higher odds of breakfast (odds ratio: 3.47; 95% confidence interval: 1.13-10.71) compared with an evening chronotype. Both morning and intermediate chronotypes were associated with higher odds of morning snack (odds ratio: 3.52; 95% confidence interval: 1.13-10.93; and odds ratio: 2.87; 95% confidence interval: 1.18-6.99) and lower odds of fast foods (odds ratio: 0.09; 95% confidence interval: 0.02-0.49; and odds ratio: 0.19; 95% confidence interval: 0.58-0.62). In the afternoon shift, a morning chronotype was associated with higher odds of breakfast (odds ratio: 5.22; 95% confidence interval: 1.85-14.72), beans (odds ratio: 3.57; 95% confidence interval: 1.19-10.74), vegetables (odds ratio: 3.52; 95% confidence interval: 1.28-9.69) and fruits (odds ratio: 4.50; 95% confidence interval: 1.55-13.07) compared with an evening chronotype. Intermediate chronotype was associated with higher odds of breakfast (odds ratio: 3.71; 95% confidence interval: 2.03-6.77), morning snacks (odds ratio: 2.45; 95% confidence interval: 1.09-5.50), vegetables (odds ratio: 1.92; 95% confidence interval: 1.03-3.58) and fruits (odds ratio: 2.50; 95% confidence interval: 1.27-4.89), and lower odds of high-energy intake post-dinner (odds ratio: 0.43; 95% confidence interval: 0.22-0.85). Adolescents with an evening chronotype had lower odds of having breakfast. Both chronotype and study shifts influenced specific food consumption habits.

Integrating habit science and learning theory to promote maintenance of behavior change: does adding text messages to a habit-based sleep health intervention (HABITs) improve outcomes for eveningness chronotype young adults? Study protocol for a randomized controlled trial

BACKGROUND

Eveningness chronotype-the tendency for later sleep and wake times-arises from a confluence of psychosocial, behavioral, and biological factors. With the onset and progression of puberty, many young people develop an eveningness chronotype, which remains prevalent through the transition into adulthood. Eveningness has been associated with increased risk for poorer health. While eveningness is modifiable, maintaining the necessary behavior changes can be challenging. The science on habits demonstrates that habit formation is a key mechanism for maintaining behavior change over time. Learning theory offers schedules of reinforcement that also hold promise for enhancing the maintenance of behavior change. The present study will evaluate the Habit-based Sleep Health Intervention (HABITs)-which combines the Transdiagnostic Intervention for Sleep and Circadian Dysfunction (TranS-C) with the science of habits-and a text message intervention informed by learning theory to attempt to sustainably modify the contributors to eveningness among young adults (18-30 years of age).

METHODS

Participants (N = 160) will be randomly allocated to HABITs and HABITs + Texts. Both interventions include HABITs which involves three 50-min sessions followed by six 30-min sessions. Alongside the latter six sessions, HABITs + Texts will concurrently receive the text message intervention. Aims 1-3 will compare HABITs + Texts to HABITs on improvements in the outcomes of (1) utilization of sleep health behaviors and habit formation, (2) sleep and circadian functioning, and (3) functioning in five health-relevant domains, in the short (post-treatment) and longer (6-month and 12-month follow-up) term. Exploratory analysis will (1) compare HABITs and HABITs + Texts on (a) if sleep health behavior habit formation mediates the effects of intervention on improvement in outcomes and (b) if intervention effects are moderated by select variables, and (2) to evaluate if HABITs (regardless of the text message intervention) is associated with an improvement in outcomes in the short and longer term.

DISCUSSION

This study has the potential to advance knowledge on (1) the value of leveraging the science of habits and learning theory in behavior change interventions, (2) the use of a low-cost and efficient intervention for habit formation and maintenance, (3) interventions that address eveningness chronotype, and (4) processes related to behavior change during emerging adulthood.

TRIAL REGISTRATION

Clinicaltrials.gov NCT05167695. Registered on December 22, 2021.

A Longitudinal Examination between Chronotype and Insomnia in Youths: A Cross-Lagged Panel Analysis

Adolescence and young adulthood are transitional periods associated with significant changes and challenges, leading to a heightened vulnerability to sleep disturbances and mental health difficulties. This stage is often associated with an increased preference for eveningness, manifested as a later chronotype. The current study aimed to investigate the directionality of the association between chronotype, based on an individual's sleep-wake behaviour, and insomnia in young people using a two-wave panel design with a 12-month interval. A total of 370 participants aged 15-24 (mean age: 21.0 ± 2.0, 72.7% female) were recruited from local secondary schools and universities. Insomnia symptoms were assessed using the Insomnia Severity Index, while chronotype was measured using the Munich Chronotype Questionnaire. Temporal associations were analysed using a series of cross-lagged panel models. The best fitting and most parsimonious model indicated that a later chronotype at baseline predicts more severe insomnia symptoms at the 12-month follow-up after accounting for autoregressive effects. However, the opposite causal model, where baseline insomnia symptoms predicted the chronotype at the 12-month follow-up, was not supported. These findings suggest that a late chronotype may be a potential risk factor for the development of insomnia in young people, emphasising the importance of considering circadian factors in the prevention and treatment of sleep disturbances among this population.

Determination of chronotype at preschoolers: psychometric properties of the Turkish adaptation of the Morningness/Eveningness Scale (Parent Report Form)

The aim of this study is to examine the psychometric properties of the Turkish adaptation of the Morningness/Eveningness Scale (M/E Scale-Parent Report Form) family evaluation form for preschool children. The study sample consisted of 276 parents with children aged 4-6 years. The study calculated Cronbach's alpha internal consistency coefficient and corrected item-total correlations of the scale. It also determined the scale's distinctiveness, stability analyses, and convergent validity. The Turkish version of the M/E Scale (Parent Report Form), consisting of 10 items, is unidimensional. The Cronbach's alpha internal consistency coefficient of the scale was 0.80 and the corrected item-total correlation values varied between 0.51 and 0.76. There was a positive correlation at the level of 0.75 between the applications of the scale with two-week intervals and at the level of 0.63 between the single-item chronotype scale within the scope of convergent validity and the M/E Scale (Parent Report Form). This study determined a low correlation between the child's chronotype and the father's chronotype, and a moderate correlation with the mother's chronotype. The Turkish M/E Scale (Parent Report Form) was found to be valid and reliable. This scale is a short and easy-to-use measurement tool for determining the chronotypes of 4-6-year-old children.

What Is the Relationship between Chronotype and Disordered Eating in Adolescents? The EHDLA Study

BACKGROUND

Evidence assessing the relationship between chronotype and disordered eating in adolescents is scarce. The current study tried to evaluate the association between chronotype and disordered eating in a sample of Spanish adolescents.

METHODS

This secondary cross-sectional study analyzed data from the Eating Healthy and Daily Life Activities (EHDLA) study. The sample consisted of 703 adolescents (56.3% girls) aged between 12 and 17 years from the Valle de Ricote (Region of Murcia, Spain). Chronotype was assessed using the Morningness/Eveningness Scale in Children (MESC). Disordered eating was evaluated by two psychologists using the Sick, Control, One, Fat, and Food (SCOFF) questionnaire.

RESULTS

Adolescents with an eveningness chronotype showed a higher SCOFF score (estimated marginal mean [M] = 1.1; 95% confidence interval [CI] 0.7 to 1.5) in comparison with adolescents with a morningness chronotype (M = 0.7; 95% CI 0.5 to 0.8) (p = 0.010), as well as with those with an intermediate chronotype (M = 0.6; 95% CI 0.5 to 0.8) (p = 0.032). A higher predictive probability of having disordered eating was identified in adolescents with an eveningness chronotype (39.5%; 95% CI 22.8% to 59.1%), compared to adolescents with an intermediate chronotype (14.9%; 95% CI 10.8% to 20.1%) (p = 0.008) and with their counterparts with a morningness chronotype (16.9%; 95% CI 11.6% to 24.0%) (p = 0.021).

CONCLUSIONS

This study reveals that adolescents with an eveningness chronotype are more likely to exhibit disordered eating behaviors compared to those with morningness or intermediate chronotypes. These findings highlight the importance of considering chronotype in adolescent health, particularly in developing targeted interventions to prevent eating disorders.

Perception of #TheDress in childhood is influenced by age and green-leaf preference

The perception of the ambiguous image of #TheDress may be influenced by optical factors, such as macular pigments. Their accumulation during childhood could increase with age and the ingestion of carotenoid-containing foods. The purpose of this study was to investigate whether the visual perception of the dress in children would differ based on age and carotenoid preference. This was a cross-sectional, observational, and comparative study. A poll was administered to children aged 2 to 10 years. Parents were instructed to inquire about the color of #TheDress from their children. A carotenoid preference survey was also completed. A total of 413 poll responses were analyzed. Responses were categorized based on the perceived color of the dress: blue/black (BB) (n = 204) and white/gold (WG) (n = 209). The mean and median age of the WG group was higher than the BB group (mean 6.1, median 6.0 years, standard deviation [SD] 2.2; mean 5.5, median 5.0 years, SD 2.3; p = 0.007). Spearman correlation between age and group was 0.133 (p = 0.007). Green-leaf preference (GLP) showed a statistically significant difference between groups (Mann-Whitney U: p = 0.038). Spearman correlation between GLP and group was 0.102 (p = 0.037). Logistic regression for the perception of the dress as WG indicated that age and GLP were significant predictors (age: B weight 0.109, p = 0.012, odds ratio: 1.115; GLP: B weight 0.317, p = 0.033, odds ratio: 1.373). Older children and those with a higher GLP were more likely to perceive #TheDress as WG. These results suggest a potential relationship with the gradual accumulation of macular pigments throughout a child's lifetime.

Chronotype and emotion processing: a pilot study testing timing of online cognitive bias modification training

BACKGROUND

Circadian rhythms influence cognitive performance which peaks in the morning for early chronotypes and evening for late chronotypes. It is unknown whether cognitive interventions are susceptible to such synchrony effects and could be optimised at certain times-of-day.

OBJECTIVE

A pilot study testing whether the effectiveness of cognitive bias modification (CBM) for facial emotion processing was improved when delivered at a time-of-day that was synchronised to chronotype.

METHODS

173 healthy young adults (aged 18-25) with an early or late chronotype completed one online session of CBM training in either the morning (06:00 hours to 10:00 hours) or evening (18:00 hours to 22:00 hours).

FINDINGS

Moderate evidence that participants learnt better (higher post-training balance point) when they completed CBM training in the synchronous (evening for late chronotypes, morning for early chronotypes) compared with asynchronous (morning for late chronotypes, evening for early chronotypes) condition, controlling for pre-training balance point, sleep quality and negative affect. There was also a group×condition interaction where late chronotypes learnt faster and more effectively in synchronous versus asynchronous conditions.

CONCLUSIONS

Preliminary evidence that synchrony effects apply to this psychological intervention. Tailoring the delivery timing of CBM training to chronotype may optimise its effectiveness. This may be particularly important for late chronotypes who were less able to adapt to non-optimal times-of-day, possibly because they experience more social jetlag.

CLINICAL IMPLICATIONS

To consider delivery timing of CBM training when administering to early and late chronotypes. This may generalise to other psychological interventions and be relevant for online interventions where the timing can be flexible.

Long-lasting effects of disturbing the circadian rhythm or sleep in adolescence

Circadian rhythms are endogenous, near 24-hour rhythms that regulate a multitude of biological and behavioral processes across the diurnal cycle in most organisms. Over the lifespan, a bell curve pattern emerges in circadian phase preference (i.e. chronotype), with children and adults generally preferring to wake earlier and fall asleep earlier, and adolescents and young adults preferring to wake later and fall asleep later than their adult counterparts. This well-defined shift speaks to the variability of circadian rhythmicity over the lifespan and the changing needs and demands of the brain as an organism develops, particularly in the adolescent period. Indeed, adolescence is known to be a critical period of development during which dramatic neuroanatomical changes are occurring to allow for improved decision-making. Due to the large amount of re-structuring occurring in the adolescent brain, circadian disruptions during this period could have adverse consequences that persist across the lifespan. While the detrimental effects of circadian disruptions in adults have been characterized in depth, few studies have longitudinally assessed the potential long-term impacts of circadian disruptions during adolescence. Here, we will review the evidence that disruptions in circadian rhythmicity during adolescence have effects that persist into adulthood. As biological and social time often conflict in modern society, with school start times misaligned with adolescents' endogenous rhythms, it is critical to understand the long-term impacts of disrupted circadian rhythmicity in adolescence.

Subtyping at-risk adolescents for predicting response toward insomnia prevention program

BACKGROUND

Previous study has shown that a brief cognitive-behavioral prevention insomnia program could reduce 71% risk of developing insomnia among at-risk adolescents. This study aimed to evaluate the differential response to insomnia prevention in subgroups of at-risk adolescents.

METHODS

Adolescents with a family history of insomnia and subthreshold insomnia symptoms were randomly assigned to a 4-week insomnia prevention program or nonactive control group. Assessments were conducted at baseline, 1 week, and 6- and 12-month after the intervention. Baseline sleep, daytime, and mood profiles were used to determine different subgroups by using latent class analysis (LCA). Analyses were conducted based on the intention-to-treat approach.

RESULTS

LCA identified three subgroups: (a) insomnia symptoms only, (b) insomnia symptoms with daytime sleepiness and mild anxiety, and (c) insomnia symptoms with daytime sleepiness, mild anxiety, and depression. The incidence rate of insomnia disorder over the 12-month follow-up was significantly reduced for adolescents receiving intervention in subgroup 3 compared with the controls (hazard ratio [HR] = 0.37; 95% confidence interval [CI]: 0.13-0.99; p = .049) and marginally for subgroup 2 (HR = 0.14; 95% CI: 0.02-1.08; p = .059). In addition, adolescents who received intervention in subgroups 2 and 3 had a reduced risk of excessive daytime sleepiness (subgroup 2: adjusted OR [AdjOR] = 0.45, 95% CI: 0.23-0.87; subgroup 3: AdjOR = 0.32, 95% CI: 0.13-0.76) and possible anxiety (subgroup 2: AdjOR = 0.47, 95% CI: 0.27-0.82; subgroup 3: AdjOR = 0.33, 95% CI: 0.14-0.78) compared with the controls over the 12-month follow-up.

CONCLUSIONS

Adolescents at risk for insomnia can be classified into different subgroups according to their psychological profiles, which were associated with differential responses to the insomnia prevention program. These findings indicate the need for further phenotyping and subgrouping at-risk adolescents to develop personalized insomnia prevention.

Lifestyle Elements for Improving Mental and Physical Health in Japanese University Students: Subjective Sleep Quality is a Common Key Factor

This study aimed to reveal the key lifestyle elements that improve physical and mental health in university students by focusing on physical activity, nutrition, and sleep. This cross-sectional study was conducted between October 2021 and December 2021. The participants were 290 first-year students (mean age, 18.63 ± .63 years; age range, 18 to 23; 198 female). The outcomes were daily step counts measured using accelerometers, dietary intake by nutrient category, sleep duration, subjective sleep quality, exercise frequency and duration by exercise type, screen time, depression level, and subjective fatigue by body part. Depression and subjective eye fatigue represent mental and physical health outcomes. Subjective sleep quality predicted depression (β = -1.22, P < .001) and eye fatigue (β = -.23, P < .01) in the path analysis. Participants with higher subjective sleep quality performed more frequent aerobic exercise (P < .01), longer session times of physical relaxation exercise (P < .05), and shorter screen time (P < .05). Subjective sleep quality could be a key factor for high mental and physical health. Furthermore, performing aerobic and relaxation exercises and reducing screen time are important for improving the subjective sleep quality.

Solar clock and school start time effects on adolescents' chronotype and sleep: A review of a gap in the literature

Circadian rhythms are entrained by external factors such as sunlight and social cues, but also depend on internal factors such as age. Adolescents exhibit late chronotypes, but worldwide school starts early in the morning leading to unhealthy sleep habits. Several studies reported that adolescents benefit from later school start times. However, the effect of later school start time on different outcomes varies between studies, and most previous literature only takes into consideration the social clock (i.e. local time of school starting time) but not the solar clock (e.g. the distance between school start time and sunrise). Thus, there is an important gap in the literature: when assessing the effect of a school start time on chronotype and sleep of adolescents at different locations and/or seasons, the solar clock might differ and, consistently, the obtained results. For example, the earliest school start time for adolescents has been suggested to be 08:30 hours, but this school start time might correspond to different solar times at different times of the year, longitudes and latitudes. Here, we describe the available literature comparing different school start times, considering important factors such as geographic position, nationality, and the local school start time and its distance to sunrise. Then, we described and contrasted the relative role of both social and solar clocks on the chronotype and sleep of adolescents. As a whole, we point and discuss a gap in literature, suggesting that both clocks are relevant when addressing the effect of school start time on adolescents' chronotype and sleep.

Prospective study of the association between chronotypes and depressive symptoms in Chinese university students: Moderating effects of PER1 gene DNA methylation

Most studies have shown a link between chronotypes and mental health and have identified evening chronotypes (E-types) as a potential risk for depressive symptoms. However, the mechanisms behind this association remain unknown. Abnormal expression of the PER1 gene was not only associated with circadian rhythm disturbance, but also closely related to mental illness. Therefore, this study aimed to examine the association of chronotype with depressive symptoms, and further explore the moderating effects of the PER1 gene DNA methylation on chronotypes and depressive symptoms in Chinese university students. In a stratified cluster sampling design, chronotype and depressive symptoms were assessed in 1 042 university students from 2 universities in a two-year prospective survey from April 2019 to October 2020. The survey was conducted once every 6 months, corresponding to the time points in April 2019 (T0), October 2019 (T1), April 2020 (T2), and October 2020 (T3). At T0, the Morning and Evening Questionnaire 5 (MEQ-5) was adopted to assess chronotype. At T0-T3, the Patient Health Questionnaire 9 (PHQ-9) was adopted to investigate depressive symptoms. Meanwhile, at T0, participants were subjected to a health check-up trip in the hospital, and blood samples were taken from the students to measure the PER1 gene DNA methylation levels. Binary logistic regression was used to analyze the association of chronotypes with depressive symptoms. The depression/total depression group was coded as 1, while the remaining participants was defined as one group, and was coded as 0. The PROCESS plug-in of SPSS software was used to analyze the moderating effects of PER1 gene DNA methylation on the association of chronotype with depressive symptoms. After adjusting for covariates, the results indicated that T0 E-types were positively correlated with T0-T3 depression/total depression in female university students. Furthermore, the PER1 gene DNA methylation has negative moderating effects between T0 chronotype and T3 depressive symptoms and has a sex difference. This study can provide more favorable scientific value for the prevention and control of depression in university students.

Chronotype, Time of Day, and Children's Cognitive Performance in Remote Neuropsychological Assessment

Research on the influence of chronotype and time of day (TOD) on cognitive performance, especially in children, is limited. We explored potential interactive effects, hypothesizing that performance differs when comparing preferred vs. non-preferred TOD. In total, 76 morning-type (MT = 37) or evening-type (ET = 39) children from the third and fourth grades (48.7% girls; M age = 8.05; SD age = 0.51), identified through the Children Chronotype Questionnaire, completed two 30-min neuropsychological assessment sessions via videoconference on the first (9:00) or last hour (16:00) of the school day. The protocol included neuropsychological tests targeting memory, language, and attention/executive domains. The results revealed an interactive effect of medium size between chronotype and TOD on a Rapid Alternating Stimulus (Naming) Task. MT and ET performed faster in asynchrony conditions (morning for ET; afternoon for MT). Additionally, ET outperformed MT in a Backward Digit Span Task, irrespective of TOD. TOD also influenced performance on an Alternating Verbal Fluency Task, with both MT and ET children performing better in the morning. These results underscore the importance of chronotype and TOD in children's cognitive performance, particularly in working memory and verbal fluency. Children assessed during non-preferred TOD exhibited better performance on some cognitive tasks, challenging the assumption that optimal times always yield superior results.

The relationship between chronotype and food addiction: Serial mediation of social jetlag and psychological pain

This study evaluates how food addiction is related to chronotype, social jetlag, and psychological pain. Of the participants (n = 1,035 university students), 16.6% had a morning chronotype, 25.1% had an evening chronotype, and 25.1% were clinically addicted to eating. The mean sleep durations for participants were 7.41 ± 2.18 h and 8.95 ± 3.0 h on weekdays and weekends, respectively. The mean misalignment time for social jetlag was 1.45 ± 1.5 h. Food addiction, psychological pain, and social jetlag levels were high among participants with the evening chronotype. The risk factors for food addiction included being female, having an evening chronotype, and having high body mass index levels and psychological pain. The total indirect effect of psychological pain and social jetlag on the relationship between chronotype and food addiction was 20.6%. However, the social jetlag effect is relatively minor compared to psychological pain. The significant conclusions of this study are as follows. Clinical food addiction is prevalent among students, and a strong direct correlation between chronotype and food addiction was observed. The study emphasizes the importance of being aware of chronotype and mental status in establishing a healthy diet and lifestyle.

Cardiorespiratory fitness and circadian rhythms in adolescents: a pilot study

Although cardiorespiratory fitness (CRF), an important marker of youth health, is associated with earlier sleep/wake schedule, its relationship with circadian rhythms is unclear. This study examined the associations between CRF and rhythm variables in adolescents. Eighteen healthy adolescents (10 females and 8 males; Mage = 14.6 ± 2.3 yr) completed two study visits on weekdays bracketing an ambulatory assessment during summer vacation. Visit 1 included in-laboratory CRF assessment (peak V̇o2) using a ramp-type progressive cycle ergometry protocol and gas exchange measurement, which was followed by 7-14 days of actigraphy to assess sleep/wake patterns and 24-h activity rhythms. During Visit 2, chronotype, social jetlag (i.e., the difference in midsleep time between weekdays and weekends), and phase preference were assessed using a questionnaire, and hourly saliva samples were collected to determine the dim light melatonin onset (DLMO) phase. All analyses were adjusted for sex, pubertal status, and physical activity. Greater peak V̇o2 was associated with earlier sleep/wake times and circadian phase measures, including acrophase, UP time, DOWN time, last activity peak (LAP) time, and chronotype (all P < 0.05). Peak V̇o2 was negatively associated with social jetlag (P = 0.02). In addition, the mixed-model analysis revealed a significant interaction effect between peak V̇o2 and actigraphy-estimated hour-by-hour activity patterns (P < 0.001), with the strongest effects observed at around the time of waking (0600-1000). In healthy adolescents, better CRF was associated with an earlier circadian phase and increased activity levels notably during the morning. Future studies are needed to investigate the longitudinal effects of the interactions between CRF and advanced rhythms on health outcomes.NEW & NOTEWORTHY In healthy adolescents, better cardiorespiratory fitness, as assessed by the gold standard measure [laboratory-based assessment of peak oxygen consumption (V̇o2)], was associated with earlier circadian timing of sleep/wake patterns, rest-activity rhythms and chronotype, and less social jetlag. These findings highlight the close interrelationships between fitness and rhythms and raise the possibility that maintaining higher cardiorespiratory fitness levels alongside earlier sleep/wake schedule and activity rhythms may be important behavioral intervention targets to promote health in adolescents.

Sleep in young people: What works now and where to? A meta-review of behavioural and cognitive interventions and lifestyle factors

OBJECTIVES

1) Systematically review meta-analyses and systematic reviews that (a) explored health/lifestyle factors affecting sleep, and/or (b) investigated behavioral/psychological sleep interventions in young people (10-25-years); 2) Evaluate the quality of published literature, and, if an intervention; 3) Examine method and effectiveness of mode of delivery, to inform current clinical practice and research direction.

METHOD

A systematic search of Embase (n = 45), MEDLINE (n = 67), Web of Science (n = 375), Google Scholar (n = 138), and hand-searching was conducted. After full review, 12 papers were selected, 2 systematic reviews without, and 10 with, meta-analyses. Six examined associations between sleep and lifestyle/health, and six examined cognitive-behavioral (n = 4), or school education (n = 2), programs.

RESULTS

Electronic media use, type of day (week/end), sex, age, culture/geographical location, substance use, family environment, and evening light exposure were negatively associated with sleep, in young people. Only cognitive and/or behavioral interventions of at least 2 × 1-hr sessions improved sleep.

CONCLUSION

This paper informs sleep recommendations for young people and advises that ≥ 2 × 1-hr sessions of cognitive behavioral or behavioral therapy is the minimum to improve sleep in young people. School-based sleep interventions do not produce long-term change.

Is chronotype linked with adherence to the Mediterranean diet among adolescents? The EHDLA study

BACKGROUND

No previous study has evaluated the relationship between chronotype and adherence to the Mediterranean diet among adolescents. The aim of the present study was to assess the association between chronotype and adherence to the Mediterranean diet in a sample of Spanish adolescents aged 12-17 years.

METHODS

This study examined secondary data from 820 adolescents (55.5% girls) from the Eating Healthy and Daily Life Activities (EHDLA) study, which included a representative sample of adolescents aged 12-17 years from the Valle de Ricote (Region of Murcia, Spain). Adolescents' chronotype was evaluated with the Morningness/Eveningness Scale in Children. Adherence to the Mediterranean diet was determined through the Mediterranean Diet Quality Index for Children and Teenagers.

RESULTS

The proportion of adolescents with an optimal Mediterranean diet was 37.6%. In relation to chronotype, we found that 24.5%, 69.4%, and 6.1% of the adolescents were classified as morning, intermediate, and evening types, respectively. After adjusting for several covariates, both evening- and intermediate-type adolescents showed lower odds of having optimal adherence to the Mediterranean diet (evening-type: odds ratio [OR] = 0.30, confidence interval [CI] 95% 0.12-0.72; intermediate-type: OR = 0.62, CI 95% 0.44-0.87) than morning-type adolescents.

CONCLUSIONS

Chronotype could affect adherence to the Mediterranean Diet in adolescents, so it should be a factor to be considered in future studies assessing eating habits.

IMPACT

No previous study has evaluated the relationship between chronotype and adherence to the Mediterranean diet among adolescents. Both evening- and intermediate-type adolescents showed lower odds of having optimal Mediterranean diet adherence than morning-type adolescents. These findings may indicate a need to promote eating healthy habits based on a more holistic approach, not only on the total energy expenditure or in specific food groups but also on the chronotype.

Nonlinear associations between insomnia symptoms and circadian preferences in the general population: Symptom-specific and lifespan differences in men and women

OBJECTIVES

This study investigated (non)linear associations between different eveningness characteristics (bedtime, wake time, morning affect, and peak performance time) and insomnia symptoms (difficulties initiating sleep, difficulties maintaining sleep, and nonrestorative sleep) in a large general population sample.

METHODS

The data came from digital surveys about insomnia (Minimal Insomnia Scale) and circadian preferences (Children's Chronotype Questionnaire/Composite Scale of Morningness) completed by the Dutch general population (37,389 participants aged 4-91years, 42.4% men) in the Lifelines cohort substudy Comorbid Conditions of ADHD.

RESULTS

Using generalized additive modeling, we found that different characteristics of eveningness related to insomnia either exponentially (later wake time/peak performance time, worse morning affect) or quadratically (early and late bedtime/midpoint of sleep). While difficulties initiating sleep and nonrestorative sleep were strongly associated with all eveningness characteristics, difficulties maintaining sleep related only to earlier bedtimes. These relationships were similar for men and women but varied partly in shapes and strengths across the lifespan. Additional analyses showed that bedtime and wake time were associated with insomnia symptoms only when their combination would result in an unusually long or short preferred time in bed.

CONCLUSION

The association between eveningness and insomnia symptoms highly depends on whether eveningness is reflected by daytime performance or sleep-wake time. The pattern and strength of these associations also vary depending on age and insomnia symptom, but less so on sex. Future sleep-related research and policies relying on circadian preferences should account for the nonlinearity, dimension/symptom-related specificity and age-related differences in the association between eveningness and insomnia symptoms.

Sleep tight! Adolescent sleep quality across three distinct sleep ecologies

Background and objectives

Good sleep quality, associated with few arousals, no daytime sleepiness and self-satisfaction with one's sleep, is pivotal for adolescent growth, maturation, cognition and overall health. This article aims to identify what ecological factors impact adolescent sleep quality across three distinct sleep ecologies representing a gradient of dense urbanity to small, rural environments with scarce artificial lighting and no Internet.

Methodology

We analyze variation of sleep efficiency, a quantitative measure of sleep quality-defined as the ratio of total time spent asleep to total time dedicated to sleep-in two agricultural indigenous populations and one post-industrial group in Mexico (Campeche = 44, Puebla = 51, Mexico City = 50, respectively). Data collection included actigraphy, sleep diaries, questionnaires, interviews and ethnographic observations. We fit linear models to examine sleep efficiency variation within and between groups.

Results

We found that sleep efficiency varied significantly across sites, being highest in Mexico City (88%) and lowest in Campeche (75%). We found that variation in sleep efficiency was significantly associated with nightly exposure to light and social sleep practices.

Conclusions and implications

Our findings point toward contextual cost-benefits of sleep disruption in adolescence. We highlight the need to prioritize research on adolescent sleep quality across distinct developmental ecologies and its impact on health to improve adolescent wellbeing through evidence-based health practices.

The relations between chronotype, stressful life events, and impulsivity in the Adolescent Brain Cognitive Development (ABCD) study

Circadian rhythm disturbances, especially circadian phase delays are associated with impulsive behaviors and have been implicated in psychiatric disorders. Chronotype is a developmentally regulated proxy measure of circadian phase. Past studies have investigated the relationship between chronotype and trauma and found that trauma is associated with evening chronotypes, suggesting the course of chronotype development may be affected by adverse childhood experiences (ACEs). However, the relationships among chronotype, impulsivity and ACEs have largely been studied in a pairwise manner using small, cross-sectional cohorts. We hypothesized that in a cohort of high-risk youth, childhood trauma would be associated with later chronotype, and later chronotype would be associated with higher rates of impulsivity. We analyzed a cross-sectional sample (n = 966) from Year 2 of adolescents at high risk for psychiatric disorders from the ABCD study who were characterized for chronotype, stressful life events, and impulsivity. We used a hierarchical regression model to examine the relationship between chronotype, stressful life events, and impulsivity using the Munich Chronotype Questionnaire (MCTQ), the Life Events Scale, Urgency, Premeditation, Perseverance and Sensation Seeking (UPPS) Impulsive Behavior scale. We found associations between eveningness, stressful life events, and all dimensions of impulsivity. Increased eveningness was associated with a higher number of stressful life events and increased impulsivity. Understanding the role of stressful life events and impulsivity in those predisposed towards eveningness is useful because it may improve our understanding of the biological mechanisms that contribute to psychiatric disorders, and lead to better prevention and treatment efforts using interventions such as increased lifestyle regularity and daytime light exposure.

Sex Differences in the Relationship between Chronotype and Eating Behaviour: A Focus on Binge Eating and Food Addiction

BACKGROUND

Men are more likely than women to have subthreshold overeating disorders. Lifestyle plays a role as a determinant, while chronotype is an emerging factor. Chronotype explains the natural preferences of wakefulness and activity throughout the day: evening chronotypes (E-Types), those most productive in the evening, have been linked with unhealthy dietary patterns and a higher propensity to substance addiction than morning types (M-Types).

METHODS

We carried out a cross-sectional study on 750 overweight or obese adults (70% females, 48 ± 10 years, BMI 31.7 ± 5.8 kg/m2). The Binge-Eating Scale, the Yale Food Addiction Scale 2.0 (YFAS 2.0), the reduced Morningness-Eveningness Questionnaire (rMEQ), and the MEDAS questionnaire were used to assess binge eating, food addiction, chronotype, and adherence to the Mediterranean diet, respectively.

RESULTS

No differences in BES binge-eating and FA food-addiction scores occurred between chronotypes, but we found significant interactions between sex × rMEQ score. While women showed the same prevalence for binge eating and food addiction across all chronotypes, binge eating and food addiction risk increased with reducing rMEQ score in men, indicating that being male and E-Type increases the risk association of binge eating and/or food addiction prevalence.

CONCLUSIONS

chronotype is associated with binge eating and food addiction in men, emphasizing the link between chronobiology and sex differences as determinants in appetite and eating behaviour dysregulation and in overweight and obesity.

Social jetlag longitudinally predicts internalizing and externalizing behavior for adolescent females, but not males

Biological changes contribute to preferences for later bed and wake times during adolescence, yet the social constraints of school start times necessitate early wake times. This often results in social jetlag (i.e. misalignment between preferred sleep timing on weekends and school days). We examined whether social jetlag predicts adolescent internalizing and externalizing behavior over time and/or whether associations differ based on sex. We used data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development Study (n = 767) to test whether social jetlag at 6th grade (ages 12-13 years) predicted internalizing and externalizing behavior at age 15 years and whether child sex moderated associations. Controlling for internalizing and externalizing behavior at 6th grade (ages 12-13 years), results were that social jetlag at 6th grade (ages 12-13 years) predicted more internalizing and externalizing behaviors at age 15 for females, but not males. These findings show that social jetlag during early adolescence confers risk for internalizing and externalizing behavior in females at mid-adolescence. Greater attention should be placed on identifying and addressing social jetlag in adolescent females.

Obesogenic sleep patterns among Chinese preschool children: A latent profile and transition analysis of the association sleep patterns and obesity risk

OBJECTIVE

This paper utilized a person-centered approach to examine whether sleep patterns on school and free days are associated with obesity risk in preschool children aged 3-6 years.

METHODS

The cross-sectional analysis included 204 children from the Wuhan Healthy Start Project with valid sleep data in at least four consecutive days gathered via Actigraph GT3X+. Based on three domains of sleep duration, sleep onset, and sleep offset, we used latent profile analysis to identify distinct sleep patterns on school and free days separately. Additionally, we conducted latent transition analysis to explore the probabilities of sleep patterns transitions between school and free days. The multivariate logistic regression model investigated the associations of sleep patterns with overweight/obesity (OWO) (BMI ≥ age- and sex-specific 85th percentile) and abdominal obesity (AO) (WC ≥ age- and sex-specific 75th percentile).

RESULTS

Two sleep patterns were identified for school days: "EL-sc" (early-to-sleep/longer-duration) (n = 119; 58.3%) and "LS-sc" (late-to-sleep/shorter-duration) (n = 85; 41.7%). Similarly, "LES-fr" (late-to-sleep/early-to-wake/shorter-duration) (n = 118; 57.8%) and "ELL-fr" (early-to-sleep/late-to-wake/longer-duration) (n = 86; 42.2%) patterns were identified for free days. LTA categorized the participants into four distinct transition groups, i.e., "EL-sc→ELL-fr" (32.9%), "EL-sc→LES-fr" (24.0%), "LS-sc→LES-fr" (33.8%), and "LS-sc→ELL-fr" (9.3%). Compared with the "ELsc→ELL-fr", the "LS-sc→LES-fr" had a higher risk of OWO (AOR 4.76; 95% CI: 1.39-20.33) and AO (AOR, 2.78; 95% CI, 1.21-6.62), respectively. Neither "EL-sc→LES-fr" (AOR, 1.11; 95% CI, 0.14-6.67) nor "LS-sc→ELL-fr" (AOR, 0.74; 95% CI, 0.03-6.14) was significantly associated with OWO. Likewise, no significant association was observed for "EL-sc→LES-fr" (AOR, 0.96; 95% CI, 0.35-2.62) and "LS-sc→ELL-fr" (AOR, 0.56; 95% CI, 0.11-2.18) with AO.

CONCLUSIONS

"LS-sc→LES-fr" pattern is significantly associated with an increased risk of general and abdominal obesity, indicating its obesogenic nature. Furthermore, although not statistically associated with obesity outcomes, "LS-sc→ELL-fr" and "EL-sc→LES-fr" patterns exhibit a semi-obesogenic characteristic. In addition, we identified a concerning trend that preschool children are at risk of transitioning to and persisting in sleep patterns characterized by delayed and shorter sleep. These findings underscore the importance of implementing interventions and strategies to address sleep patterns as a crucial step to minimize the risk of obesity.

Social jetlag as a predictor of depressive symptoms among Japanese adolescents: Evidence from the Adolescent Sleep Health Epidemiological Cohort

OBJECTIVES

Social jetlag, a circadian misalignment, has been associated with depressive symptoms in the general and working populations. However, evidence for this association in adolescents is inconsistent. This cross-sectional study aimed to investigate the association between social jetlag and depressive symptoms among Japanese adolescents and to evaluate differences by sex.

METHODS

The participants were 1493 students (13.6 ± 0.9years, 52.4% girls) from five junior high schools. Questionnaires, including demographic information and the Munich ChronoType Questionnaire, were distributed. Social jetlag was defined as the difference between midsleep on weekdays and weekends, and was categorized as <0 hour (negative), 0 to <1 hour, 1 to <2 hours, or ≥2 hours. Depressive symptoms were assessed using the Birleson Depression Self-Rating Scale for Children. Multivariate logistic regression was used to estimate the odds ratio with adjustments for potential confounders, such as puberty- and lifestyle-related factors.

RESULTS

The distribution of students with <0 hour, 0 to <1 hour, 1 to <2 hours, and ≥2 hours of social jetlag was 9.4%, 37.0%, 33.3%, and 20.4%, respectively. The multivariate-adjusted model revealed that social jetlag ≥2 hours and <0 hour were associated with an elevated risk of depressive symptoms among girls and boys, respectively. These associations were nonlinear for both sexes in restricted cubic spline analyses.

CONCLUSIONS

Social jetlag is associated with depressive symptoms among adolescents. Specifically, the risk of depressive symptoms increased with positive social jetlag scores for girls and negative social jetlag scores for boys.

Circadian preference and physical and cognitive performance in adolescence: A scoping review

Adolescence is a crucial period of development which coincides with changes in circadian rhythmicity. This may augment the impact of circadian preference on performance in this group. We aimed to scope the literature available on chronotypes and their effect on physical and mental aspects of performance in adolescents. Studies were identified by systematically searching bibliographical databases and grey literature. The Morningness-Eveningness Questionnaire was the most frequently reported tool for circadian preference assessment. Academic achievement was the most prevailing outcome, with evidence suggesting that morning type adolescents tend to outperform evening types, yet the results vary depending on multiple factors. Performance in tests of intelligence and executive functions was generally better at optimal times of the day (synchrony effect). Physical performance was examined in 8 studies, with very heterogeneous outcomes. Although the associations between circadian preference and performance in adolescents are evident in some areas, there are many factors that may be involved in the relationship and require further investigation. This review highlights the assessment of physical performance in relation to chronotypes, the multidimensional assessment of circadian preference, and the need for longitudinal studies as priorities for further research.Protocol: OSF Registration - Public registration, DOI: 10.17605/OSF.IO/UCA3Z.

Daily rhythms, light exposure and social jetlag correlate with demographic characteristics and health in a nationally representative survey

The timing of daily activity in humans have been associated with various demographic and health-related factors, but the possibly complex patterns of confounding and interaction between these has not been systematically explored. We use data from Hungarostudy 2021, a nationally representative survey of 7000 Hungarian adults to assess the relationship between self-reported chronotype, social jetlag (using the Munich Chronotype Questionnaire), demographic variables and self-reported health and demographic variables, including ethnic minority membership. Supporting the validity of self-reports, participants with later chronotypes reported the lowest daytime sleepiness at a later clock time. We found that older age, female sex, a more eastward and southward geographical position, residence in a smaller settlement, less education and income, religiousness and cohabiting with small children were associated with an earlier chronotype. Younger age, higher education and income, and cohabiting with small children were associated with increased social jetlag. Of the 48 health-related variables surveyed, the relationship with both chronotype and social jetlag were mostly accounted for by age, sex, and socioeconomic effects, but we identified alcohol consumption, smoking, and physical activity as predictors of both social jetlag and chronotype, while a number of disorders were either positively or negatively associated with chronotype and social jetlag. Our findings from a large, nationally representative sample indicate that both biological and social factors influence chronotype and identified both demographic and health-related variables as risk factors for social jetlag. Our results, however, do not support a causal relationship between light exposure and mental health.

Earlier Bedtime and Its Effect on Adolescent Sleep Duration

BACKGROUND AND OBJECTIVES

Sleep duration decreases by ∼10 minutes per year throughout adolescence. A circadian phase delay and changes in homeostatic sleep regulation enable adolescents to stay up later. We determine if teens are able to increase sleep duration by advancing bedtime and whether this ability changes with age.

METHODS

A younger cohort of 77 participants ranging in age from 9.9 to 16.2 years were studied annually for 3 years. An older cohort of 67 participants ranging in age from 15.0 to 20.6 years was studied only once. Annually, participants kept each of 3 different time in bed (TIB) schedules (7, 8.5, and 10 hours) for 4 consecutive nights. Participants kept their habitual weekday rise times; TIB was altered by advancing bedtimes. We report polysomnography-measured sleep durations from the fourth night of the TIB schedule.

RESULTS

Despite increases in sleep onset latency and wake after sleep onset, sleep duration increased with TIB as bedtime was advanced. Average (SE) sleep duration increased from 402.8 (1.6) minutes with 7 hours to 470.6 (2.1) minutes with 8.5 hours to 527.5 (3.0) minutes with 10 hours TIB. Sleep duration decreased with age (1.55 [0.48] minutes/year), but the TIB effect on sleep duration did not (TIB by age interaction, P = .42).

CONCLUSIONS

Adolescents can substantially increase sleep duration by advancing bedtime, and this ability does not change between ages 10 and 21 years. Additional research is needed to determine how to translate these findings from experiment-controlled sleep schedules to real-world sleep duration increases.

A better alignment between chronotype and school timing is associated with lower grade retention in adolescents

Schools start early in the morning all over the world, contrasting with adolescents' late chronotype. Interestingly, lower academic performance (i.e. grades or qualifications) was associated with later chronotypes. However, it is unclear whether it is a direct effect of chronotype or because students attend school too early to perform at their best. Moreover, little is known about how this affects students' academic success beyond their grades. To address this gap in knowledge, we studied how school timing and chronotype affect grade retention (i.e. repeat a year) in a unique sample of students randomly assigned to one of three different school timings (starting at 07:45, 12:40, or 17:20). Even when controlling for academic performance, we found that later chronotypes exhibit higher odds of grade retention only in the morning, but not in later school timings. Altogether, ensuring a better alignment between school timing and students' biological rhythms might enhance future opportunities of adolescents.

Onsite versus home-office: differences in sleep patterns according to workplace

Background and objective

This study aimed to evaluate the sleep patterns of students and employees working onsite versus those working from home during the COVID-19 pandemic using actigraphy.

Methods

A total of 75 students/employees (onsite: N = 40, home-office: N = 35; age range: 19-56 years; 32% male; 42.7% students, 49.3% employees) were studied between December 2020 and January 2022 using actigraphy, a sleep diary, and an online questionnaire assessing sociodemographics and morningness-eveningness. Independent-sample t-tests, paired-sample tests, and a multivariate general linear model adjusting for age (fixed factors: sex and work environment) were applied.

Results

Overall, onsite workers had significantly earlier rise times (7:05 [SD: 1:11] versus 7:44 [1:08] hours) and midpoints of sleep (2:57 [0:58] versus 3:33 [0:58] hours) on weekdays compared to home-office workers. Sleep efficiency, sleep duration, variability of sleep timing, and social jetlag did not differ between the groups.

Discussion

Home-office workers showed a delay in sleep timing that did not affect any other sleep parameters such as sleep efficiency or nighttime sleep duration. The work environment had only marginal impact on sleep patterns and thus sleep health in this sample. Sleep timing variability did not differ between groups.

Supplementary Information

The online version of this article (10.1007/s11818-023-00408-5) contains supplementary material 1 and 2, which is available to authorized users.

Exploring the associations between the Morningness-Eveningness-Stability-Scale improved (MESSi) and the higher-order personality factors

Morningness-eveningness refers to individual differences in the sleep-wake cycle. Research indicates that morningness-eveningness is associated with the Big Five (neuroticism, extraversion, openness to experience, agreeableness, conscientiousness) and the Big Two (alpha-stability, beta-plasticity) personality factors. However, the latter has not yet been tested within the multidimensional approach to morningness-eveningness. In the present study, we have adapted the Morningness-Eveningness-Stability-Scale improved (MESSi) to Polish (https://osf.io/rcxb5) to explore the associations between its subscales (morning affect, eveningness, distinctness) and the Big Two personality traits in a sample of 1106 participants (559 women and 547 men) aged 18 to 55 (M = 36.26, SD = 9.90). In bivariate correlations, morning affect was positively related to alpha-stability and beta-plasticity, distinctness was correlated negatively with alpha-stability and beta-plasticity, while eveningness was positively correlated only with beta-plasticity. Furthermore, the confirmatory factor analysis supported the original three-factor structure of the Polish version of MESSi, while the associations with affect and the symptoms of depression and anxiety attested to its validity. Overall, the present study provides the first evidence for the associations between MESSi subscales and the Big Two personality traits, as well as shows a good fit of the three-factor structure of MESSi in the Polish population.

Chronotype and sensory-processing sensitivity: A cross-sectional survey

Here we examined the possibility of a relationship of sensory processing sensitivity (SPS) with chronotype in a German-speaking sample of N = 1807 (1008 female, 799 male) with a mean age of 47.75 ± 14.41 y (range: 18-97 y). The data were collected using an anonymous online questionnaire (Chronotype: one item of the Morning-Evening-Questionnaire, as well as typical bedtimes on weekdays and weekends; SPS: German version of the three-factor model ; Big Five: NEO-FFI-30) between 21 and 27 April 2021. Results. We found morningness to correlate with the SPS facet low sensory threshold (LST), while eveningness correlated to aesthetic sensitivity (AES) and marginally significant to ease of excitation (EOE). Discussion: The results show that the correlations between chronotype and the Big Five personality traits are not consistent with the direction of the correlations between chronotype and the SPS facets. The reason for this could be different genes that are responsible for the individual traits influence each other differently depending on their expression.

Association between COVID-19 lockdown and sleep behaviors in Korean adolescents

To find the effect of coronavirus disease 2019 (COVID-19)-related sleep behavior changes using school-based self-reported data from a nationally representative Korean adolescent population. We analyzed web-based self-reported data from the Korean Youth Risk Behavior Web-based Survey in 98,126 participants (51,651 in 2019 [before the COVID-19 pandemic]; 46,475 in 2020 [during COVID-19 pandemic] 12 through 18 years old were included in this study. Self-report questionnaires were used to assess socioeconomic status, health behaviors, psychological factors, and sleep patterns. During the COVID-19 pandemic, Korean adolescents had a later weekend bedtime (≥1:00 am: 68.2% vs 71.5%, P < .001) and late weekend wake time (≤7:00 am: 13.3% vs 10.7%, P < .001) compared to before COVID-19 pandemic. Average sleep duration (434.7 ± 102.6 vs 428.2 ± 100.4 minutes; P < .001) was significantly lower during the COVID-19 pandemic and weekend catch-up sleep >2 hours (42.1% vs 43.7%; P < .001), late chronotype (17.1% vs 22.9%, P < .001) were significantly higher during COVID-19 pandemic. After adjusting for multiple confounding variables, short sleep duration (≦5 hours, odds ratio [OR] 1.14; 95% confidence interval [CI] 1.10-1.19), 6 hours, OR 1.07; 95% CI 1.03-1.12), long weekend catch-up sleep (OR, 1.08; 95% CI, 1.06-1.11) and late chronotype (OR, 1.43; 95% CI, 1.38-1.47) were significantly associated with COVID-19 pandemic. The COVID-19 pandemic was associated with changes in sleep behavior among Korean adolescents, resulting in later bed and wake-up times, increased weekend catch-up sleep, and a shift of chronotype toward eveningness.

Later school start time is associated with longer school day sleep duration and less social jetlag among Norwegian high school students: Results from a large-scale, cross-sectional study

The present study explored the associations between school start time and sleep habits among older adolescents, and whether these associations depended on circadian preference. The sample comprised 4010 high school students aged 16-17 years who completed a web-based survey on habitual school start time, sleep, and health. The survey included the Munich ChronoType Questionnaire, and the short version of the Horne-Östberg Morningness-Eveningness Questionnaire. Students were categorised according to habitual school start time (before 08:00 hours, 08:00 hours, 08:15 hours, 08:30 hours or after 08:30 hours) and circadian preference (morning, intermediate or evening). Data were analysed using two-way analyses of variance (school start time × circadian preference) and linear regression analyses. Results showed an overall effect of school start time on school day sleep duration (main effect, p < 0.001), with the latest school starters having the longest, and the earliest school starters having the shortest sleep duration (7:03 hr versus 6:16 hr; Tukey HSD p < 0.001). Similarly, later school starters generally reported shorter social jetlag and later school day wake-up times than earlier starting students (both main effect p < 0.001). Circadian preference did not modify these associations (interaction effects p > 0.05). In the crude regression analysis, 15 min later school start was associated with 7.2 min more sleep (p < 0.001). School start time remained a significant predictor of school day sleep duration when adjusted for sex, parental educational level and circadian preference (p < 0.001). Results suggest that school start time is a significant predictor of school day sleep duration among adolescents.

Beyond sleep: A multidimensional model of chronotype

Chronotype can be defined as an expression or proxy for circadian rhythms of varied mechanisms, for example in body temperature, cortisol secretion, cognitive functions, eating and sleeping patterns. It is influenced by a range of internal (e.g., genetics) and external factors (e.g., light exposure), and has implications for health and well-being. Here, we present a critical review and synthesis of existing models of chronotype. Our observations reveal that most existing models and, as a consequence, associated measures of chronotype have focused solely or primarily on the sleep dimension, and typically have not incorporated social and environmental influences on chronotype. We propose a multidimensional model of chronotype, integrating individual (biological and psychological), environmental and social factors that appear to interact to determine an individual's true chronotype with potential feedback loops between these factors. This model could be beneficial not only from a basic science perspective but also in the context of understanding health and clinical implications of certain chronotypes as well as designing preventive and therapeutic approaches for related illnesses.

Associations between chronotype, sleep quality, maternal mental health, and child development in mother-infant dyads

OBJECTIVE/BACKGROUND

Studies on circadian rhythms throughout development and their physiological and behavioral impacts at early stages are still scarce. Previous studies have shown that mother-infant interactions are important for both sleep and child development. In this cross-sectional study we investigated whether infants' chronotype, sleep and development were associated with their respective mothers' chronotype, sleep, mental health and socioeconomic status.

PATIENTS/METHODS

the following were used to evaluate mothers: the Morningness-Eveningness Questionnaire (MEQ), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS) and Self-Reporting Questionnaire 20 (SRQ-20). To assess the infants' characteristics, the following were used: the 19th question from the Morningness-Eveningness Questionnaire (MEQ), infant nocturnal midpoint of sleep (iMSF), Brief Infant Sleep Questionnaire (BISQ) and Ages and Stages Questionnaire-3 (ASQ3). Socioeconomic aspects were assessed using the Brazilian Economic Class Criterion of the Brazilian Association of Research Companies (ABEP).

RESULTS

A hundred and eight mother-infant dyads participated in the study. Sleep disorders were observed in 38 (35%) infants and atypical development (ASQ3) in 35 (32%). The infants' sleep phases were partially explained by the mother's chronotype. Infants' sleep duration was negatively correlated with sleep latency, which was higher in the group with atypical development. Mothers of infants with sleep disorders or discordant chronotypes (32%) had higher Pittsburgh scores (worse sleep quality) and higher SRQ-20 scores (screen for Common Mental Disorders).

CONCLUSIONS

We found evidence for the contribution of sleep quality and chronotypes to mothers' mental health and infant development. However, further studies are needed to confirm the influence of sleep and circadian phenotypes in the early stages.

Child Eveningness as a Predictor of Parental Sleep

Child eveningness has been associated with many adverse outcomes for children. The aim of this study was to assess whether child eveningness poses a risk to parental sleep quality in follow-up. A total of 146 children (57% adopted, 47% boys, mean age at follow-up 5.1 years [standard deviation 1.7]) completed a 1-week actigraph recording to analyze their sleep twice, 1 year apart. The parents completed the Child ChronoType Questionnaire for their child and a short version of the Morningness-Eveningness Questionnaire for themselves and the Jenkins Sleep Scale for their sleep quality. Linear regression analyses showed that subjective parental sleeping problems at baseline were associated with subjective parental sleeping problems at follow-up. A morning-type child decreased the risk of parental sleeping problems at the 1-year follow-up compared to the child evening chronotype. Additionally, the child intermediate chronotype decreased the risk of maternal sleeping problems at the 1-year follow-up compared to the evening chronotype of the child. Parents of evening-type children experienced more sleeping problems in the follow-up, compared to parents of morning-type children. This finding encourages parents and professionals to steer the diurnal rhythm of evening-type children toward an earlier daily routine.

The circadian preferences in the context of sociodemographic indicators and lifestyle

Circadian preferences are frequently used as a synonym for chronotype. Both terms are based on different principles and are measured by a variant questionnaire. We focused on circadian preferences, delimited as an individual preference for the timing of various activities, and their relationship to the selected sociodemographic factors. All participants (n = 2068) filled out online questionnaires including MEQ, MCTQ, and sociodemographic information (age, sex, place of residence, marital status, childcare, education, financial security, physical and mental health). Although the concept of chronotype and circadian preference differ, the mutual correlation was high. Our results of the observed variables are similar to other studies. We revealed evening preference is related to a higher probability of living in a big city, having a single life, a higher risk of smoking, worse health status, and worse financial security. We observed a higher social jet lag among them. Our research complies with previous studies, which found that in some areas, people with evening preferences evince worse results. Due to the evening preference, these people are at a disadvantage, and the society's setting for morning operations can lead to a deepening of these differences. We recommend further research, which would focus on the practical application of results to the everyday life of participants to create preventive programs aimed at reducing the negative impact of evening preferences on life.

Bedtime procrastination and chronotype differentially predict adolescent sleep on school nights and non-school nights

OBJECTIVES

Bedtime procrastination (BTP) refers to the tendency to delay sleep beyond an intended bedtime, in favor of continuing evening activities. BTP has been associated with negative sleep outcomes (later timing, shorter duration, poorer quality), and is viewed as a problem of exercising self-control. BTP could be particularly challenging in adolescents, given the combined effects of increasing bedtime autonomy, later chronotype, and a still developing self-control capacity. Thus far, research on BTP has only been based on self-report measures. Here we examined the influence of BTP on adolescent sleep, using objective measures of sleep.

METHODS

About 121 adolescents aged 14-19 years completed a survey on BTP, sleep quality, chronotype, and mental health. Subsequently, habitual sleep was actigraphically monitored for up to 2 weeks, and participants completed a temporal discounting task (a proxy for impulsivity). Associations between BTP, chronotype, and actigraphy-measured sleep were examined for school nights and non-school nights separately.

RESULTS

Greater BTP was associated with poorer subjective sleep, eveningness chronotype, and higher daytime fatigue, as well as higher anxiety/depression scores. Measured using actigraphy, greater BTP predicted later bedtimes and shorter sleep duration on school nights, even when controlling for chronotype. On non-school nights, eveningness chronotype, but not BTP, predicted later bedtimes and wake-up times. BTP was not correlated with temporal discounting.

CONCLUSIONS

Bedtime procrastination exerts significant influence on subjective and objective sleep measures in adolescents. Its effects are most prominent on school nights and can be separated from the effects of chronotype, which has stronger effects on sleep timing on non-school nights.

Relationship of Circadian Rhythm in Behavioral Characteristics and Lipid Peroxidation of Brain Tissues in Mice

OBJECTIVE

This study aimed to explore the relationship among several indices of circadian rhythms and lipid peroxidation of brain tissue in mice.

METHODS

After entrainment of 4-week-old mice, one group was disrupted their circadian rhythms for three days and the other group for seven days (n = 10, respectively). After a recovery period, the Y-maze test, the elevated plus maze test, the tail suspension test, and the forced swimming test were conducted. To assess lipid peroxidation in brain tissue, thiobarbituric acid reactive substances were measured in the cortex, hippocampus, and cerebellum.

RESULTS

When circadian rhythms were disrupted and adapted back to their original rhythm, the recovery time of the 7-day disruption group (median 3.35 days) was significiantly faster than one of the 3-day disruption group (median 4.87 days). In the group with a 7-day disruption, mice that had recovered their rhythms early had higher malondialdehyde levels in their hippocampus compared to those with delayed recovery. The entrainment of circadian rhythms was negatively correlated with the malondialdehyde level of brain tissue. The behavioral test results showed no differences depending on the disruption durations or recovery patterns of circadian rhythms.

CONCLUSION

These results suggest that disruption types, recovery patterns, and the entrainment of circadian rhythms are likely to affect oxidative stress in adolescents or young adult mice. Future study is needed to confirm and specify these results on the effects of circadian rhythms on oxidative stress and age-dependent effects.

Environmental preferences of adolescents within a low ecological footprint country

As Cuba achieves one of the lowest per capita ecological footprints in the world, the country's overshoot day was on 1 December 2019, while some European countries already reach this limit in February (e.g., Luxembourg), monitoring the environmental preferences of the Cuban younger generation may offer valuable behavioral or pedagogical insights into such a society. As accepted standardized measures exist in the scales of 2-Major Environmental Values (2-MEV) and the General Ecological Behavior (GEB), both measures are following the necessary psychometric requirement, as they have the unique advantage of repeated independent confirmation (and thus provide an external validity). These captured 40 items of reported behavior originating in six subscales that total in a single main cover score. The first one (2-MEV) monitors individual biocentric and anthropocentric preferences with a 20 item-set by relying upon these two higher-order factors of "Preservation" (PRE) and "Utilization" (UTL). Although many language versions already exist (33 in the case of the 2-MEV) for verifying validities and reliabilities of both scales, a country such as Cuba may affirm that this is due to expected cultural differences as well as their exceptionally low global footprint. Additionally, neither the individual connectedness with nature nor the diurnal preferences within the linear structural model showed a substantial relationship to PRE or UTL. Nevertheless, all the regression scores follow the expected positive or negative directions, albeit not all the fit scores turned out as satisfactorily. Apparently, the applied measures secure a good basis for measuring the attitudinal and behavioral framework, but will need further fine tuning to completely monitor the environmental preferences of Cuban adolescents.

Endogenous circadian temperature rhythms relate to adolescents' daytime physical activity

Circadian rhythms relate to multiple aspects of health and wellbeing, including physical activity patterns. Susceptible circadian regulation predisposes to circadian misalignment, poor sleep, sleep deprivation, increased sleepiness, and thereby sedentary behavior. Adolescents' circadian regulation is particularly vulnerable, and may lead to sedentary behavior. To investigate which factors associate strongest between physical activity (PA) and circadian behavior, we conducted multimodal circadian rhythm analyses. We investigate how individual characteristics of habitual circadian patterns associate with objectively measured PA. We studied 312 adolescents [70% females) (56% with delayed sleep phase (DSP)], mean age 16.9 years. Circadian period length, temperature mesor (estimated 24 h midline) and amplitude (difference between mesor and peak) were measured using distally attached thermologgers (ibutton 1922L, 3-day-measurement). We additionally utilized algorithm-formed clusters of circadian rhythmicity. Sleep duration, timing, DSP, and PA were measured using actigraphs (GeneActiv Original, 10-day-measurement). We found that continuous circadian period length was not associated with PA, but lower mesor and higher amplitude were consistently associated with higher levels of PA as indicated by mean Metabolic Equivalent (METmean) and moderate-to-vigorous PA (MVPA), even when controlling for sleep duration. Separate circadian clusters formed by an algorithm also reflected distinct patterns of PA accordingly. Late sleepers and those with DSP were less likely to engage in MVPA compared to non-DSP and had more sedentary behavior. Adolescents who engage in higher levels or high-intensity PA have better circadian regulation, as measured by different objective methods including distal temperature measurements as well as actigraphy-measured sleep-wake behavior.

Characteristic Sleep Patterns and Associated Obesity in Adolescents

Poor sleep adversely affects health and may cause obesity. Poor sleep includes short sleep duration, low quality of sleep, and sleep discrepancy. Although most studies have focused on the association between sleep duration and obesity, poor sleep is a significant risk factor for obesity. Adolescents have characteristic sleep patterns which correspond to poor sleep. Adolescents sleep late due to various biological and psychosocial factors; also, they wake up early to be on time for school. This causes them to sleep less. To make up for this sleep debt, adolescents sleep more on non-school days, which causes sleep discrepancies. Therefore, since adolescents have characteristic sleep patterns, an in-depth investigation is needed to identify whether poor sleep is a risk for obesity. This article presents an overview of the characteristic sleep patterns of adolescents, and reviews studies on the association of each sleep pattern with obesity.