Adolescent sleep misalignment: a chronic jet lag and a matter of public health

Melatonin use in managing insomnia in typically developing (TD) children: A technical report

Although melatonin is widely used globally for the management of insomnia in children and adolescents, there are few clinical guidelines available for healthcare practitioners, particularly in typically developing (TD) children. Because existing data are either sparse or inconclusive, a task force comprised of pediatric sleep researchers and clinicians was established by the International Pediatric Sleep Association (IPSA) to first examine the available literature and to develop a set of evidence-based (when possible) and consensus-based recommendations to guide practitioners in decision-making regarding melatonin use in pediatric insomnia. A summary of the evidence pertaining to melatonin's use in pediatric clinical settings, and efficacy and safety in TD children is presented below as a companion to an accompanying list of specific recommendations.

Associations between real-life light exposure patterns and sleep behaviour in adolescents

One of the most striking changes in the regulation of sleep-wake behaviour during adolescence is circadian phase delay. Light exposure synchronises circadian rhythms, impacting sleep regulation, however, the influence of real-life light exposure on sleep variations remains less clear. We aimed to describe the sleep and light exposure patterns of high school students with comparable schedules and socio-economic backgrounds, and to evaluate whether there was any association between them, considering chronotype. We analysed five school days and two free days of actigraphy records, from 35 adolescents (24 female, mean age: 16.23 ± 0.60). The sample was described using the Sleep Regularity Index (SRI), chronotype (actigraphy MSFsc), and self-reported diurnal preference (Morning/Evening Scale). Regression models were constructed to assess the impact of light exposure (daytime and nighttime) on subsequent sleep episodes; and to confirm whether the associations could be an indirect consequence of chronotype. Despite following similar routines, the SRI varied considerably (48.25 to 88.28). There was compatibility between the actigraphy proxy for chronotype and the self-reported diurnal preference, extracted using the circadian rhythm scale for adolescents. Less light exposure during the day was associated with later sleep onset and shorter sleep duration. An increase of 100 lux in average daytime light exposure advance of 8.08 minutes in sleep onset and 7.16 min in sleep offset. When the regressions were controlled for chronotype, these associations persisted. These findings facilitate discussions regarding the behavioural aspect of the impact of real-life light exposure on sleep and its potential as a target for interventions aiming to enhance adolescents' sleep quality.

A sleep promotion program for insufficient sleep among adolescents: a pilot feasibility randomized controlled trial

STUDY OBJECTIVES

We examined the feasibility, acceptability, and impact of a sleep promotion program (SPP).

METHODS

This pilot trial randomly assigned adolescents (13-15 years of age) with insufficient sleep duration and irregular sleep timing to SPP-continuation (n = 24; SPP in month 1, continuation treatment in month 2) or monitoring-SPP (n = 20; monitoring in month 1, SPP in month 2). SPP included 1 clinician session and at-home delivery of web-based reports of each youth's sleep diary data with accompanying intervention questions that prompt youth to engage in sleep behavior change. Attrition rate primarily measured feasibility. Program satisfaction measured acceptability. Total sleep time, sleep timing, and sleep timing regularity were measured via sleep diary at baseline, Follow-up 1, and Follow-up 2 (each ∼1 month apart). Linear mixed-effects models compared treatment arms on changes in sleep from baseline to Follow-up 1 (month 1). We also compared changes in sleep during month 1 to changes in sleep during month 2 among SPP-continuation participants.

RESULTS

Attrition rate was 8.5%, and 96.5% of participants rated the quality of care received as good or excellent. In month 1, SPP-continuation youth showed a significantly greater increase in mean total sleep time than monitoring-SPP youth (0.57 vs -0.38 hours; contrast = 0.95; confidence interval = 0.14, 1.76; P = .024). SPP-continuation participants showed an increase in total sleep time during month 1 (0.51 hours) but a decrease during month 2 (-0.74 hours; contrast = -1.24; confidence interval = -2.06, -0.42; P = .005). No other significant effects were observed.

CONCLUSIONS

SPP is highly feasible, acceptable, and associated with a significant increase in total sleep time early in treatment.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Targeted Intervention for Insufficient Sleep among Typically-Developing Adolescents; URL: https://clinicaltrials.gov/ct2/show/NCT04163003; Identifier: NCT04163003.

CITATION

Levenson JC, Goldstein TR, Wallace ML, et al. A sleep promotion program for insufficient sleep among adolescents: a pilot feasibility randomized controlled trial. J Clin Sleep Med. 2025;21(3):529-541.

Social jetlag and sleep habits in children and adolescents: Associations with autonomy (bedtime setting and electronics curfew) and electronic media use before sleep

For young people attending school, social jetlag (SJL) refers to discrepancy in sleep/wake timing between school days and weekends. This study investigated SJL in school-aged children and adolescents in England and whether this is associated with age, gender, and sleep habits including bedtimes and electronic media use. Students (school y 5-13; typical age 9-18 y) completed the 2021 OxWell Student Survey. In total 19,760 participants (55% female) reported on sleep/wake timing, rules concerning bedtime setting on school night/weekend, electronic media curfew, and frequency of social media use and video gaming before sleep intention. The mean SJL was 1 h 53 min (SD = 1 h 7 min) and peaked at 2 h 7 min at age 15. Multiple regression analysis revealed SJL was positively associated with age and being male was associated with slightly lower SJL than being female. After controlling for age and gender, weekend bedtime setting (β = 0.21), frequency of social media use before sleep (β = 0.16) and video gaming before sleep (β = 0.12) were the strongest predictors of SJL. Findings suggest that household rules regarding weekend bedtimes and less electronic media use before sleep may be connected with lower SJL as well as more regular sleep timing across the whole week.

The Relationship Between Intraindividual Sleep-Wake Variability and Mental Health in Adolescents

OBJECTIVE

We investigated the relationship between irregular sleep-wake patterns and other aspects of sleep and mental health among adolescents.

METHODS

Community-based sample of adolescents (n = 200, mean age 16.8; 61.7% female) completed baseline assessment (i.e. sleep quality, daytime sleepiness, depressive symptoms, social anhedonia, problematic alcohol use), and 7-8 consecutive days of wearing wrist actigraphy. Irregular sleep-wake patterns were assessed via two methods, both based on actigraphy, to capture day-to-day irregularity (intraindividual variability, IIV) and weekly irregularity (social jet lag, SJL). The Bayesian variability method was performed to calculate IIV in total sleep time (TST), sleep onset, and offset time. SJL was quantified as the actual difference in the sleep midpoint on school days versus non-school days.

RESULTS

Greater IIV in TST was associated with poorer sleep quality (B = 1.66, 95% CI, 0.14, 3.31, p < .05), and greater depressive symptoms (B = 0.72, 95% CI, 0.17, 1.35, p < .05), while greater IIV in sleep offset time was associated greater depressive symptoms (B = 0.63, 95% CI, 0.03, 1.28, p < .05), and greater problematic alcohol use (B = 0.70, 95% CI, 0.12, 1.35, p < .05), all after adjusting for age, sex, family SES, alcohol drinks, and SJL. No significant association was found with sleep onset time. Greater SJL was associated with poorer sleep quality (B = 0.40, 95% CI, 0.27, 0.54, p < .001) and fewer problematic alcohol uses (B = -0.05, 95% CI, -0.09, -0.00, p < .05), when adjusting for age, sex, family SES, and alcohol drinks.

CONCLUSION

Our findings add to a growing body of research on irregularity in sleep-wake patterns and clinical implications.

Adolescent circadian rhythm disruption increases reward and risk-taking

Introduction

Circadian rhythm disturbances have long been associated with the development of psychiatric disorders, including mood and substance use disorders. Adolescence is a particularly vulnerable time for the onset of psychiatric disorders and for circadian rhythm and sleep disruptions. Preclinical studies have found that circadian rhythm disruption (CRD) impacts the brain and behavior, but this research is largely focused on adult disruptions. Here, we hypothesized that adolescent CRD would have a greater effect on psychiatric-related behaviors, relative to adult disruption.

Methods

We determined the long-term behavioral and neurobiological effects of CRD during early adolescence by exposing mice to 12 h shifts in the light/dark cycle. Adult mice were exposed to the same CRD paradigm. Behavior testing began approximately 4 weeks later for both groups. To identify possible mechanisms, we also measured gene expression in brain regions relevant to circadian rhythms, mood and reward.

Results

CRD during early adolescence, but not adulthood, persistently increased exploratory drive (risk-taking behavior) and cocaine preference when tested later in life. Interestingly, we found sex differences when intravenous cocaine self-administration was tested. While female mice with a history of adolescent CRD had a greater propensity to self-administer cocaine, as well as increased motivation and cue-induced reinstatement, male adolescent CRD mice had reduced motivation and extinction responding. Importantly, we found that transcripts in the SCN were affected by adolescent CRD and these were largely distinct across sex.

Conclusion

Overall, adolescent CRD in mice caused persistent increases in risky behavior, cocaine reward and cocaine self-administration, which suggests that CRD during adolescence may predispose individuals toward substance use disorders. Future research is required to elucidate how adolescent CRD affects behaviors relevant to mood-and substance use-related disorders across the 24-h day, as well as to identify intervention strategies to alleviate disruption during adolescence and novel therapeutic approaches once symptoms have begun.

Sleep medicine and chronobiology education among Brazilian medical students

Chronobiology and sleep medicine are pivotal disciplines for understanding human health. Additionally, the lack of training in medical schools exacerbates the underdiagnosis and undertreatment of sleep disorders. This study investigated the exposure of Brazilian medical students to chronobiology and sleep medicine during their undergraduate education and assessed their knowledge in these areas. The study was conducted between December 2021 and June 2022 through the administration of an online questionnaire (Google Forms) to medical students in the final two years of undergraduate studies. The questionnaire gathered student data (i.e., sex, age, and educational institution), research data (stage in the medical program with exposure to chronobiology or sleep medicine), and responses to a questionnaire on basic knowledge of sleep medicine and chronobiology (adapted from Assessing Sleep Knowledge in Medical Education - ASKME). A total of 240 students from medical schools in Brazil participated, 4.6% of whom reported no exposure to either subject, with exposure declining as students progressed through the curriculum. Only 3.7% reported specific disciplines covering these topics. Over half of the students encountered learning barriers, such as limited curriculum time. Despite these challenges, the accuracy rate in responses regarding chronobiology and sleep medicine was 79.75%, positively correlating with exposure level and knowledge retention. This study underscores the urgent need for enhanced education in sleep medicine and chronobiology within Brazilian medical schools. It offers insights into the current landscape of sleep medicine education in Brazil and lays groundwork for future efforts to integrate these essential subjects into medical school curricula.

A Complex Relationship Among the Circadian Rhythm, Reward Circuit and Substance Use Disorder (SUD)

The human brain not only controls the various physiological functions but is also the prime regulator of circadian rhythms, rewards, and behaviors. Environmental factors, professional stress, and social disintegration are regarded as the initial causative factors of addiction behavior. Shift work, artificial light exposure at night, and chronic and acute jet lag influence circadian rhythm dysfunction. The result is impaired neurotransmitter release, dysfunction of neural circuits, endocrine disturbance, and metabolic disorder, leading to advancement in substance use disorder. There is a bidirectional relationship between chronodisruption and addiction behavior. Circadian rhythm dysfunction, neuroadaptation in the reward circuits, and alteration in clock gene expression in the mesolimbic areas influence substance use disorder (SUD), and chronotherapy has potential benefits in the treatment strategies. This review explores the relationship among the circadian rhythm dysfunction, reward circuit, and SUD. The impact of chronotherapy on SUD has also been discussed.

Bedtime Regularity and Sleep Sufficiency in Children With Tourette Syndrome

BACKGROUND

Despite research demonstrating sleep disturbance in children with Tourette syndrome (TS), few studies have examined bedtime regularity and sleep sufficiency, two important sleep health dimensions. Therefore, this study examined bedtime regularity and sleep sufficiency in children with TS relative to matched healthy control subjects, and its associated demographic, clinical, and behavioral factors.

METHODS

Participants were 384 parents or caregivers of children aged three to 17 years, including 192 with current TS and 192 matched healthy control subjects drawn from the 2020-2021 cycle of the National Survey of Children's Health. Parents completed questions assessing demographic (i.e., age, race, sex), clinical (i.e., attention-deficit/hyperactivity disorder [ADHD], autism spectrum disorder, anxiety, depression, tic severity, behavioral or conduct problems, ADHD medication, health condition-related impairment), and behavioral (i.e., screen time) characteristics. Mann-Whitney U test and chi-square test of independence were performed to compare groups on bedtime regularity and sleep sufficiency, respectively. Ordinal regression and binary logistic regression without and with backward elimination were performed to evaluate indicators of bedtime regularity and sleep sufficiency, respectively, in children with TS.

RESULTS

Children with current TS had significantly poorer bedtime regularity, but not sleep sufficiency, relative to matched healthy control subjects. In children with TS, anxiety and two or more hours of daily screen time were associated with higher likelihood of poor bedtime regularity. Autism was associated with lower likelihood of insufficient sleep, and depression was associated with increased likelihood of insufficient sleep.

CONCLUSIONS

Findings put forth screen time, anxiety, and depression as intervention targets to optimize sleep health in children with TS.

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.

Social jetlag and trajectories of mood symptoms and reward responsiveness in individuals at low-risk, high-risk, and with bipolar spectrum disorders: An ecological momentary assessment study

A specific type of sleep disruption, social jetlag, involves an incongruence of sleep time between weekends and weekdays. This study investigated relationships between social jetlag and mood symptom lability and trajectories of daily reward responsiveness and mood symptoms. Participants (N = 130) from three groups (moderate reward sensitivity, high reward sensitivity, and high reward sensitivity with a diagnosed bipolar spectrum disorder [BSD]) were recruited from an ongoing longitudinal study based on their self-reported reward sensitivity and a diagnostic interview. For this study, they completed 20 days of ecological momentary assessment (EMA) of reward responsiveness and mood symptoms and a daily sleep diary. Social jetlag was significantly associated with differences in trajectories of depressive symptoms between groups. Specifically, greater social jetlag was associated with a greater increase in depressive symptoms over the 20 days for participants in the high reward sensitivity and BSD groups compared to the moderate reward sensitivity group. Social jetlag also was significantly associated with depressive symptom lability during the EMA period, but this finding was reduced to a trend toward significance when controlling for self-reported sleep duration. The study adds to the literature with methodological strengths including the EMA design and assessment of symptom and reward responsiveness trajectories.

Stride-to-Stride Fluctuations of Human Gait Are Affected By Chronobiology: An Exploratory Study

Physiological processes present daily oscillations of ≈24 h, called circadian rhythms. Motor performance, for example, reaches its peak in the afternoon, although this can be affected by chronotype. Certain motor activities, for example, walking, can also be affected by circadian rhythms. Healthy walking exhibits stride-to-stride fluctuations with a fractal-like structure that enables adaptability. While pathology and aging are shown to lead to random-like fluctuations; and, therefore, decreased adaptability; the influence of circadian rhythms remains unknown. This study investigates how these fluctuations present in healthy gait are affected by the time of day and chronotype. Eighteen young adults walk for 10 min every 2 h, from 8 a.m. to 6 p.m. Footswitches are used to determine heel-strike and calculate stride time. Then, detrended fluctuation analysis is used to calculate fractal scaling. A mixed-model Analysis of Variance is used and followed by a backward stepwise elimination process. Tukey's tests are used for pairwise comparisons. The statistical model shows the effect of time during the day (12 p.m. exhibits a higher fractal scaling compared to 8 a.m.); and chronotype (evening-types exhibit higher fractal scaling compared to morning-types). This study reveals the influence of chronobiology on stride-to-stride fluctuations. These findings open new perspectives to integrate circadian medicine in biomechanics.

Sensation seeking, drinking motives, and going out mediate the link between eveningness and alcohol use and problems in adolescence

The present study was aimed at obtaining a more comprehensive understanding of the possible mediating factors in the morningness-eveningness → alcohol consumption relation. We explored the role of mediators such as sensation seeking, the frequency of going out in the evenings, and drinking motives. We tested the proposed mediation model via structural equation modeling based on cross-sectional research conducted among Hungarian adolescents and young adults (N = 1695, 42.5% male, Mage = 18.98, SDage = 1.89). The outcomes included the frequency of alcohol consumption and problematic drinking. Both alcohol consumption and problematic drinking were predicted in similar directions and magnitudes by sensation seeking, "going out," and coping drinking motives. However, eveningness still had a significant direct effect on alcohol consumption and problematic drinking after we controlled for sensation seeking, going out, and drinking motives. For problematic drinking, the possible role of drinking motives seems to be higher and more complex than it is for alcohol consumption. The mediators, such as sensation seeking, the amount of time spent out in the evenings, and drinking motives, can explain the eveningness → alcohol consumption relationship and should be targeted for alcohol prevention programs among evening-type adolescents.

Bridging the gap: leveraging implementation science to advance pediatric behavioral sleep interventions

STUDY OBJECTIVES

This review synthesizes the pediatric behavioral sleep intervention (BSI) evidence base, summarizes challenges in translating BSIs from research to practice, and provides recommendations for integrating implementation science methods to advance pediatric BSI research.

METHODS

We briefly review the common behavioral sleep disturbances among youth, discuss the pediatric BSIs with well-established evidence, and identify gaps in pediatric BSI research. We then identify contributors to the dearth of research evaluating pediatric BSIs in accessible settings and present a model for applying implementation science strategies to address identified gaps across the continuum of translational research.

RESULTS

Relatively few BSI trials include older children and adolescents. Similarly, there is limited research evaluating BSIs among racially and ethnically minoritized children and families and/or those of lower socioeconomic status backgrounds. Access to scalable and easily disseminable tools to treat pediatric sleep disturbances early in their development is crucial for promoting positive child outcomes. To address these gaps, researchers should apply implementation science theories, models, and frameworks to design new interventions for implementation, adapt existing interventions with end users and settings in mind, conduct hybrid effectiveness-implementation trials, and test implementation strategies.

CONCLUSIONS

Given the prevalence and consequences of poor sleep across developmental periods, pediatric BSIs must be effective as well as adaptable, scalable, and easily disseminable. Implementation science theories, models, and frameworks can enhance access to, engagement in, and the implementation and dissemination of scalable BSIs across diverse pediatric care settings and heterogeneous populations.

CITATION

Levenson JC, Williamson AA. Bridging the gap: leveraging implementation science to advance pediatric behavioral sleep interventions. J Clin Sleep Med. 2023;19(7):1321-1336.

Chronotype in college science students is associated with behavioral choices and can fluctuate across a semester

Many students self-report that they are "night owls," which can result from neurodevelopmental delays in the circadian timing system. However, whether an individual considers themselves to be an evening-type versus a morning-type (self-reported chronotype) may also be influenced by academic demands (e.g. class start times, course load) and behavioral habits (e.g. bedtime social media use, late caffeine consumption, daytime napping). If so, then chronotype should be malleable. We surveyed 858 undergraduate students enrolled in demanding science courses at up to three time points. The survey assessed morning/evening chronotype, global sleep quality, academics, and behavioral habits. Evening and morning-type students showed similar demographics, stress levels, and academic demands. At baseline measurements, relative to morning-types, evening-types showed significantly worse sleep quality and duration as well as 22% greater bedtime social media usage, 27% greater daytime napping duration, and 46% greater likelihood of consuming caffeine after 5pm. These behavioral habits partially mediated the effects of self-reported chronotype on sleep quality/duration, even after controlling for demographic factors. Interestingly, 54 students reported switching from being at least moderate evening-types at baseline to being at least moderate morning-types later in the semester and 56 students showed the reverse pattern (6.3% of students switched from "definitely" one chronotype to the other chronotype). Evening-to-morning "chrono-switchers" consumed less caffeine after 5pm and showed significantly better sleep quantity/quality at the later timepoint. Thus, some students may consider themselves to be night owls in part because they consume caffeine later, take more daytime naps, or use more social media at bedtime. Experimental work is needed to determine whether nudging night owls to behave like morning larks results in better sleep health or academic achievement.

Adolescent use of social media and associations with sleep patterns across 18 European and North American countries

OBJECTIVE

Over the past decade, concurrent with increasing social media use (SMU), there has been a shift toward poorer sleep among adolescents in many countries. The purpose of this study was to examine the cross-national associations between adolescent SMU and sleep patterns, by comparing 4 different categories of SMU (nonactive, active, intense, and problematic use).

DESIGN, SETTING, AND PARTICIPANTS

Data were from 86,542 adolescents in 18 European and North American countries that participated in the 2017/18 Health Behaviour in School-aged study.

MEASUREMENTS

Mixed-effects linear regression models were used to examine cross-national associations between 4 SMU categories and adolescent sleep duration, bedtime and social jetlag derived from self-reported data.

RESULTS

For all countries combined, nonactive SMU was associated with longer sleep, earlier bedtimes, and less social jetlag, compared to active SMU, although the differences were minor. By comparison, intense and problematic SMU were associated with less sleep and later bedtimes on both school and nonschool days, and greater social jetlag, compared to active SMU. While findings were relatively consistent between countries, some differences were observed, suggesting that the national and cultural context may be important in interpreting results.

CONCLUSIONS

These findings suggest that both intense and problematic SMU are associated with poorer sleep patterns in adolescents across most countries. Further research is needed to identify effective policies, programs, and messaging to promote the healthy use of social media and prevent potential negative impacts on adolescent sleep.

Use of a Fitbit-like device in rats: Sex differences, relation to EEG sleep, and use to measure the long-term effects of adolescent ethanol exposure

BACKGROUND

Sleep difficulties and rhythm disturbances are some of the problems associated with adolescent binge drinking. Recently, animal models of alcohol-induced insomnia have been developed. However, studies in human subjects have recently focused not only on nighttime EEG findings but also on daytime sleepiness and disrupted activity levels as typically measured by activity tracking devices such as the "Fitbit." We sought to develop and test a Fitbit-like device (the "FitBite") in rats and use it to track rest-activity cycles following adolescent alcohol exposure.

METHODS

The effects of 5 weeks of adolescent ethanol vapor or control conditions were evaluated in 48 male and female Wistar rats using FitBite activity while intoxicated, and during acute (24 h post-vapor exposure) and chronic withdrawal (4 weeks post-vapor exposure). Data were analyzed using activity count and cosinor analyses. Fourteen rats were subsequently implanted with cortical electrodes, and data from the FitBite were compared with EEG data to determine how well the FitBite could identify sleep and activity cycles.

RESULTS

Female rats were generally more active than males, with higher circadian rhythm amplitudes and mesors (rhythm-adjusted means) across a 24-h period. There were significant correlations between EEG-estimated sleep and activity counts using the FitBite. When the rats were tested during intoxication after 4 weeks of ethanol vapor exposure, they had significantly less overall activity. Disruptions in circadian rhythm were also found with significant decreases in the circadian amplitude, mesor, and a later shift in the acrophase. At 24 h of ethanol withdrawal, rats had more episodes of activity with shorter durations during the daytime, when rats are expected to spend more of their time sleeping. This effect remained at 4 weeks following withdrawal, but circadian rhythm disruptions were no longer present.

CONCLUSIONS

A Fitbit-like device can be successfully used in rats to assess rest-activity cycles. Adolescent alcohol exposure produced circadian rhythm disturbances that were not observed after withdrawal. Fragmentation of ultradian rest-activity cycles during the light period was found at 24 h and 4 weeks after withdrawal and support data demonstrating the presence of sleep disturbance long after alcohol withdrawal.

The effect of brain-derived neurotrophic factor Val66Met polymorphism on adolescent activity and rest rhythms, circadian preferences and attentional performance

BACKGROUND

Variations in circadian regulating mechanisms generate different individual preferences in respect of sleep and activity timing, which are known as chronotypes. In this sense, specifically during adolescence, there is a greater tendency for an eveningness chronotype. One factor that has been shown to have an impact on circadian rhythm patterns, as well as on some aspects of cognitive function, is the relatively common Val66Met (rs6265) polymorphism in the human brain-derived neurotrophic factor gene.

OBJECTIVE

This study aimed to evaluate the effect of the BDNF Val66Met polymorphism on the performance of adolescents in attentional tests, circadian preferences and activity-rest rhythm.

METHODS

85 healthy high school students completed the Morningness-Eveningness Questionnaire to assess their circadian preferences; were evaluated using the Psychological Battery for Attention Assessment; and were categorized as carriers and non-carriers of the rs6265 polymorphism using the TaqMan rt-PCR technique. A subsample of 42 students had their activity/rest rhythm recorded by actigraphy for nine days from which sleep parameters were estimated.

RESULTS

Circadian preference did not affect attentional performance (p > 0.1), but the time that the students attended school had an impact on all types of attention with morning shift students scoring higher, regardless of chronotype (p < 0.05). The presence of the BDNF Val66Met polymorphism was associated only with alternate attention performance (p < 0.05). Regarding actigraphy evaluation, the carriers of the polymorphism demonstrated significantly higher total time in bed, total sleep time, social jetlag, and earlier sleep onset.

CONCLUSIONS

The results indicate some degree of adaptation in the students' attentional performance, according to their school schedules. The presence of BDNF polymorphism demonstrated a counterintuitive impact on attentional performance, comparing to previous findings. The findings reinforce the effect of genetic traits on sleep-wake rhythm parameters, when objectively evaluated.

Sleep deprivation among adolescents in urban and indigenous-rural Mexican communities

Comparing the nature of adolescent sleep across urban and more isolated, rural settings through an ecological, cross-cultural perspective represents one way to inform sleep nuances and broaden our understanding of human development, wellbeing and evolution. Here we tested the Social Jetlag Hypothesis, according to which contemporary, urban lifestyles and technological advances are associated with sleep insufficiency in adolescents. We documented the adolescent sleep duration (11-16 years old; X̅ = 13.7 ± 1.21; n = 145) in two small agricultural, indigenous and one densely urban context in Mexico to investigate whether adolescents in socio-ecologically distinct locations experience sleep deprivation. Sleep data was assembled with actigraphy, sleep diaries and standardized questionnaires. We employed multilevel models to analyze how distinct biological and socio-cultural factors (i.e., pubertal maturation, chronotype, napping, gender, working/schooling, access to screen-based devices, exposure to light, and social sleep practices) shape adolescent sleep duration. Results suggest that the prevalence of adolescent short sleep quotas is similar in rural, more traditional environments compared to highly urbanized societies, and highlight the influence of social activities on the expression of human sleep. This study challenges current assumptions about natural sleep and how adolescents slept before contemporary technological changes occurred.

Two-year changes in sleep duration are associated with changes in psychological distress in adolescent girls and boys: the fit futures study

Objective

Studies indicate an inverse association between sleep duration and psychological distress. We aimed to explore associations between changes in sleep duration and changes in psychological distress in girls and boys.

Methods

The Fit Futures Study is a broad adolescent study providing data from 373 girls and 294 boys aged 15–18 years collected in 2010/2011 (FF1) and 2012/2013 (FF2). Psychological distress was measured by the Hopkins Symptom Checklist (HSCL-10) and sleep duration was self-reported. Change score variables were calculated as the change between baseline and follow-up for sleep duration and HSCL-10, respectively. Associations between changes in sleep duration and changes in HSCL-10 were explored by linear regressions, in gender-stratified analyses.

Results

At FF1, girls and boys slept on average 6.93 (SD = 1.08) and 7.05 (SD = 1.20) hours per night respectively, and correspondingly, 6.83 (SD = 1.19) and 6.85 (SD = 1.21) at FF2. At FF1, 22.8% of the girls and 25.8% of the boys slept ≤ 6 h per night, and correspondingly 28.0% and 28.2% at FF2. In girls and boys, one unit increase (30 min) in sleep duration was associated with a decrease in HSCL-10 score of B [95% CI] = −0.090 [−0.131, −0.048], p < 0.001, and −0.054 [−0.091, −0.017], p < 0.001, respectively. The associations remained significant after adjusting for confounders.

Conclusion

Our findings show that increased sleep duration was associated with decreased psychological distress during adolescence. Future studies should examine the causality between sleep duration and psychological distress.

Different Effects of Social Jetlag and Weekend Catch-Up Sleep on Well-Being of Adolescents According to the Actual Sleep Duration

The aim of this study was to explore the potentially different associations between two common aspects of adolescents’ life, namely social jetlag and weekend catch-up sleep, with well-being and physical health, according to the actual sleep duration, i.e., <7 h and ≥7 h. To this end, 504 participants (42.1% males), with a mean age of 16.17 (standard deviation = 1.39), were examined in the this cross-sectional study. Participants were asked to wear the Micro Motionlogger Watch actigraph (Ambulatory Monitoring, Inc., Ardlsey, NY, USA) around their non-dominant wrist for seven consecutive days in order to objectively assess social jetlag and weekend catch-up sleep. Participants were also asked to fill in the Mental Health Continuum—Short Form for the assessment of subjective, social, and psychological well-being, as well as the SF-36 Health Survey for the perception of physical health. In adolescents sleeping less than 7 h, those experiencing weekend catch-up sleep longer than 120 min reported significantly lower subjective well-being compared to those with a weekend catch-up sleep duration between 0 and 59 min. These data pointed out the detrimental effect of long weekend catch-up sleep on self-reported well-being only in adolescents getting less than the recommended amount of sleep.

Association between social jetlag and sugar-sweetened beverages (SSBs) in adolescents in Western Canada

Background

Sleep debt is linked to poor health behaviours, and adolescents may be especially vulnerable to deficit from the mismatch of their late chronotype with socially determined sleep timing. We aimed to investigate the potential association between social jetlag and sugar-sweetened beverages (SSBs) consumption among adolescents.

Methods

Cross-sectional data from 1031 adolescents (13–18 years) who participated in the population-based British Columbia Adolescent Substance Use Survey in 2012. Regression analysis using interaction terms estimated the associations between social jetlag (using self-reported weekday/weekends sleep times) and odds of SSB intake in girls and boys.

Results

On average, adolescents reported 1.59 (SD 0.73) hours of social jetlag, but girls had significantly more social jetlag (1.64) than boys (1.52). Most adolescents (84%) reported consuming SSBs, and significantly more boys (87%) than girls (81%); median SSB intake in boys was 1–2 times per week and in girls less than once per week. Significant differences in girls consuming any SSB were seen across levels of social jetlag. The odds of any SSB intake were significantly higher in adolescents with social jetlag between 1 and 2 h [odds ratio (OR): 1.6 (1.14–2.38)] and over 2 h [OR 1.87 (1.11–3.14)], compared with 1 h or less; associations were stronger and only significant in girls.

Conclusions

This study is the first to show social jetlag is a common sleep deficit that is associated with SSB intake in adolescents, particularly among teen girls.

Integration of Time-Based Recommendations with Current Pediatric Health Behavior Guidelines: Implications for Obesity Prevention and Treatment in Youth

PURPOSE OF REVIEW

Youth-onset obesity is associated with negative health outcomes across the lifespan including cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, dyslipidemias, asthma, and several cancers. Pediatric health guidelines have traditionally focused on the quality and quantity of dietary intake, physical activity, and sleep.

RECENT FINDINGS

Emerging evidence suggests that the timing (time of day when behavior occurs) and composition (proportion of time spent allocated to behavior) of food intake, movement (i.e., physical activity, sedentary time), and sleep may independently predict health trajectories and disease risks. Several theoretically driven interventions and conceptual frameworks feature behavior timing and composition (e.g., 24 h movement continuum, circadian science and chronobiology, intermittent fasting regimens, structured day hypothesis). These literatures are, however, disparate, with little crosstalk across disciplines. In this review, we examine dietary, sleep, and movement guidelines and recommendations for youths ages 0-18 in the context of theoretical models and empirical findings in support of time-based approaches. The review aims to inform a unifying framework of health behaviors and guide future research on the integration of time-based recommendations into current quantity and quality-based health guidelines for children and adolescents.

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.

Changes in sleeping habits during the pubertal years; A descriptive study conducted in Jordan

Background:

There is limited information about changes in sleeping habits during the pubertal years of development among adolescents in Jordan.

Objective:

This study examined sleeping habits at the onset and end of puberty.

Methods:

This study utilized data from a nationwide survey in Jordan.

Participants: Sleeping habits were obtained from 3,661 adolescents aged 11(onset of puberty) and 15 years (end of puberty) and their mothers using a self-reported questionnaire. The number of hours slept and bedtimes and wake-up times on both school and non-school days were examined.

Results:

On school days, 60% of 11-year-old and 34% of 15-year-old adolescents slept between 8:00-10:00 pm. On school days, the 11-year-old adolescent group reported sleeping significantly longer than the 15-year-old adolescent group, and the proportions of adolescents who met the minimal recommended sleeping hours were 64% and 54%, respectively. Sleeping hours were long for both groups attending government schools; for the 15-year-old adolescent group, sleeping hours varied with family income and maternal education. In the case of both groups, on non-school days sleeping hours varied with gender, family income, and type of school.

Conclusion:

At the end of pubertal years, adolescent sleeping habits differ significantly from those of adolescents at the onset of puberty. On school days, insufficient sleep is much evident in the case of both 11 and 15-year-old adolescent groups, but more pronounced in the latter. Nursing initiatives to address poor sleeping habits among adolescents are warranted, given their efficacy in promoting healthy growth and development within this age group.

Electric lighting, adolescent sleep and circadian outcomes, and recommendations for improving light health

Light is a potent circadian entraining agent. For many people, daily light exposure is fundamentally dysregulated with reduced light during the day and increased light into the late evening. This lighting schedule promotes chronic disruption to circadian physiology resulting in a myriad of impairments. Developmental changes in sleep-wake physiology suggest that such light exposure patterns may be particularly disruptive for adolescents and further compounded by lifestyle factors such as early school start times. This narrative review describes evidence that reduced light exposure during the school day delays the circadian clock, and longer exposure durations to light-emitting electronic devices in the evening suppress melatonin. While home lighting in the evening can suppress melatonin secretion and delay circadian phase, the patterning of light exposure across the day and evening can have moderating effects. Photic countermeasures may be flexibly and scalably implemented to support sleep-wake health; including manipulations of light intensity, spectra, duration and delivery modality across multiple contexts. An integrative approach addressing physiology, attitudes, and behaviors will support optimization of light-driven sleep-wake outcomes in adolescents.

Chronotype at the beginning of secondary school and school timing are both associated with chronotype development during adolescence

The misalignment between late chronotypes and early school start times affect health, performance and psychological well-being of adolescents. Here we test whether, and how, the baseline chronotype (i.e. chronotype at the beginning of secondary school) and the school timing affect the magnitude and the direction of the developmental change in chronotype during adolescence. We evaluated a sample of Argentinian students (n = 259) who were randomly assigned to attend school in the morning (07:45 a.m.–12:05 p.m.), afternoon (12:40 p.m.–05:00 p.m.) or evening (05:20 p.m.–09:40 p.m.) school timings. Importantly, chronotype and sleep habits were assessed longitudinally in the same group of students along secondary school (at 13–14 y.o. and 17–18 y.o.). Our results show that: (1) although chronotypes partially align with class time, this effect is insufficient to fully account for the differences observed in sleep-related variables between school timings; (2) both school timing and baseline chronotype are independently associated with the direction and the magnitude of change in chronotype, with greater delays related to earlier baseline chronotypes and later school timings. The practical implications of these results are challenging and should be considered in the design of future educational timing policies to improve adolescents’ well-being.

Epidemiology of accelerometer-based sleep parameters in US school-aged children and adults: NHANES 2011-2014

We aimed to provide objectively measured sleep parameters across lifespan by sex and race in a national representative sample of US population. The study included 11,279 participants 6 years and older from the National Health and Nutrition Examination Survey (NHANES) 2011-2014, who had at least 3 days of valid sleep parameters calculated from 7-day 24-h accelerometer recording. Sleep duration showed a U-shaped association with age and reached the minimum at age 40 and started to increase again around age 50. The clock time for sleep onset (CTSO) delayed with age and reached the maximum at about age 20. CTSO then advanced until age 50, leveled off until age 70, then advanced again after age 70. Sleep efficiency showed an overall decreasing trend across the lifespan but stabilized from age 30 to about age 60. US young adults in age 20 s are the ones who slept at the latest around midnight, while the middle aged US residents between 40 and 50 years old slept the least. Females generally present longer sleep duration than males, while more likely to have later sleep onset, particularly at older ages. Non-Hispanic Blacks showed worse sleep characteristics, i.e. sleep later, sleep shorter, and sleep less efficiently, compared to other racial groups. In conclusion, this study provides valuable insights on the characteristics of sleep habits of residents of the United States by using objectively measurements of sleep parameters and will help guide personalized advice on sleep hygiene.

Interactions between nocturnal melatonin secretion, metabolism, and sleeping behavior in adolescents with obesity

Background/objectives

Sleeping behavior and individual prospensity in sleep timing during a 24 h period, known as chronotypes, are underestimated factors, which may favor the development of obesity and metabolic diseases. Furthermore, melatonin is known to play an important role in circadian rhythm, but was also suggested to directly influence metabolism and bodyweight regulation. Since disturbed and shifted sleep rhythms have been observed in adolescents with obesity, this study aimed to investigate potential interactions between melatonin secretion, chronobiology, and metabolism. In addition, the influence of artificial light especially emitted by electronic devices on these parameters was of further interest.

Subjects/methods

We performed a cross-sectional study including 149 adolescents (mean age 14.7 ± 2.1 years) with obesity. Metabolic blood parameters (e.g., cholesterol, triglycerides, uric acid, and insulin) were obtained from patients and correlated with nocturnal melatonin secretion. Melatonin secretion was determined by measuring 6-sulfatoxymelatonin (MT6s), the major metabolite of melatonin in the first-morning urine, and normalized to urinary creatinine levels to account for the urinary concentration. Chronobiologic parameters were further assessed using the Munich ChronoType Questionnaire.

Results

Subjects with insulin resistance (n = 101) showed significantly lower nocturnal melatonin levels compared to those with unimpaired insulin secretion (p = 0.006). Furthermore, triglyceride (p = 0.012) and elevated uric acid levels (p = 0.029) showed significant associations with melatonin secretion. Patients with late chronotype showed a higher incidence of insulin resistance (p = 0.018). Moreover, late chronotype and social jetlag were associated with the time and duration of media consumption.

Conclusion

We identified an association of impaired energy metabolism and lower nocturnal melatonin secretion in addition to late chronotype and increased social jetlag (misalignment of biological and social clocks) in adolescents with obesity. This might point towards a crucial role of chronotype and melatonin secretion as risk factors for the development of pediatric and adolescent obesity.

Sleep in an At Risk Adolescent Group: A Qualitative Exploration of the Perspectives, Experiences and Needs of Youth Who Have Been Excluded From Mainstream Education

The sleep needs, experiences and viewpoints were explored for UK adolescents who have been excluded from mainstream education. Qualitative data was gathered through interviews with 9 participants, aged 11-15 years, who also completed questionnaires. The participants had symptoms of inadequate sleep, poor sleep hygiene behaviours and were not getting the recommended amount of sleep on school nights. Participants described sleep patterns involving often staying up late and having different sleep timing on weekends than weekdays and having difficulties with their sleep. Use of technology and the relevance of family were identified as important and associated with facilitating and hindering factors for sleep. Participants communicated that they lack control over aspects of their sleep and their lives. The experiences and views of the participants can inform professionals' understanding of how to collaborate with adolescents to improve their sleep and highlight that continued development of sleep education programmes is timely.

Data-driven modelling approach to circadian temperature rhythm profiles in free-living conditions

The individual variation in the circadian rhythms at the physiological level is not well understood. Albeit self-reported circadian preference profiles have been consolidated, their premises are grounded on human experience, not on physiology. We used data-driven, unsupervised time series modelling to characterize distinct profiles of the circadian rhythm measured from skin surface temperature in free-living conditions. We demonstrate the existence of three distinct clusters of individuals which differed in their circadian temperature profiles. The cluster with the highest temperature amplitude and the lowest midline estimating statistic of rhythm, or rhythm-adjusted mean, had the most regular and early-timed sleep–wake rhythm, and was the least probable for those with a concurrent delayed sleep phase, or eveningness chronotype. While the clusters associated with the observed sleep and circadian preference patterns, the entirely unsupervised modelling of physiological data provides a novel basis for modelling and understanding the human circadian functions in free-living conditions.

Social Jetlag in adolescents: From a nursing perspective

PROBLEM

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

METHODS

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

FINDINGS

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

CONCLUSIONS

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

Chronic sleep restriction triggers inadequate napping habits in adolescents: a population-based study

BACKGROUND

The prevalence of chronic sleep restriction during adolescence is a major public health issue. Napping has been adopted to alleviate sleep pressure complaints. However, it also has the potential to amplify sleep restriction due to a vicious cycle triggered by delayed sleep times. The aim of this study was to investigate sleep and napping habits in a sample of Brazilian adolescents.

METHODS

This study enrolled 1554 high school students and included the evaluation of sleep times, daytime sleepiness, sleep quality, and circadian preference. The students were asked about their napping routine, ie its frequency and duration per week.

RESULTS

The adolescent sleep recommendation was achieved by only 27.6% of the sample. Napping habit was reported by 58.1%, with 36.2% of nappers informing naps in 1-2 times per week. Prolonged naps were reported by 44.9% of nappers. Nappers had later median bedtime (23:30) and reduced time in bed (TIB) (median = 07:00 h) compared to non-nappers. The frequency of nappers who did not achieve satisfactory TIB was higher than non-nappers. In addition, nappers reported increased daytime sleepiness and poor sleep quality. Later bedtimes and reduced TIB were associated with longer nap duration. Increased sleepiness and poor sleep quality were linked to a higher nap frequency.

CONCLUSIONS

This exploratory survey demonstrated a severe sleep restriction faced by Brazilian adolescents. Napping can be an efficient strategy to counteract sleep restriction, but it needs to be adopted with caution due to the detrimental effects of frequent and prolonged naps on nocturnal sleep.

Sleep pattern and staging in elite adolescent rugby players during the in-season competitive phase compared to an age matched non-athlete population

Young athletes must contend with the constraints of elite sports on top of school commitments and the physiological processes associated with adolescence. This study assessed week and weekend sleep and schedule of activities in elite adolescent rugby players during the in-season competitive phase compared with age-matched non-athlete controls. 32 adolescents (GR: 16 elite rugby players, GC: 16 controls) from the same boarding school filled out a daily schedule of activities and a sleep diary, and wore a multichannel electroencephalogram for 14 days. They later filled out questionnaires on their sleep quality, sleepiness, and perceived stress. Both groups showed insufficient sleep duration during the week (<7 h). Only GC caught up on their sleep debt during the weekend (increased TIB, TST and time spent in REM sleep, all p < 0.001). Weekend TIB, TST and, N3 sleep remained similar to that for weekdays in GR. However, GR experienced lower sleep quality (decreased SE, increased WASO, all p < 0.01) and a decrease in REM sleep (p < 0.01). Schedules of activities showed an increase in time spent on overall activities during the weekend, mainly due to competition and sport-specific travel, which resulted in a decrease in sleep opportunity time compared with GC (p < 0.001). Δ sleep opportunity time (weekend-week) was associated with Δ TST (weekend-week), and Δ TST (weekend-week) was associated with sleepiness and perceived stress. Busy schedules during the competitive season decreased sleep opportunity time and prevented elite adolescent rugby players from catching up on their sleep at weekends.HIGHLIGHTS Adolescent rugby players have insufficient sleep during both week and weekend of the in-season competitive phaseCongested schedule prevented elite adolescent rugby players from catching up on their sleep at weekends.Sleep considerations are necessary when planning the weekend sporting schedules.

The Prevalence and Stability of Sleep-Wake Disturbance and Fatigue throughout the First Year after Mild Traumatic Brain Injury

In this prospective, longitudinal study, we aimed to determine the prevalence and stability of sleep-wake disturbance (SWD) and fatigue in a large representative sample of patients (Trondheim mild traumatic brain injury [mTBI] follow-up study). We included 378 patients with mTBI (age 16-60), 82 matched trauma controls with orthopedic injuries, and 83 matched community controls. Increased sleep need, poor sleep quality, excessive daytime sleepiness, and fatigue were assessed at 2 weeks, 3 months, and 12 months after injury. Mixed logistic regression models were used to evaluate clinically relevant group differences longitudinally. Prevalence of increased sleep need, poor sleep quality, and fatigue was significantly higher in patients with mTBI than in both trauma controls and community controls at all time points. More patients with mTBI reported problems with excessive daytime sleepiness compared to trauma controls, but not community controls, at all time points. Patients with complicated mTBI (intracranial findings on computed tomography or magnetic resonance imaging) had more fatigue problems compared to those with uncomplicated mTBI, at all three time points. In patients with mTBI who experienced SWDs and fatigue 2 weeks after injury, around half still had problems at 3 months and approximately one third at 12 months. Interestingly, we observed limited overlap between the different symptom measures; a large number of patients reported one specific problem with SWD or fatigue rather than several problems. In conclusion, our results provide strong evidence that mTBI contributes significantly to the development and maintenance of SWDs and fatigue.

How Are Adolescents Sleeping? Adolescent Sleep Patterns and Sociodemographic Differences in 24 European and North American Countries

PURPOSE

Insufficient and poor sleep patterns are common among adolescents worldwide. Up to now, the evidence on adolescent sleep has been mostly informed by country-specific studies that used different measures and age groups, making direct comparisons difficult. Cross-national data on adolescent sleep that could inform nations and international discussions are lacking. We examined the sleep patterns of adolescents across 24 countries and by gender, age, and affluence groups.

METHODS

We obtained sleep data on 165,793 adolescents (mean age 13.5 years; 50.5% girls) in 24 European and North American countries from the recent cross-sectional Health Behaviour in School-aged Children surveys (2013-2014 and 2017-2018). For each country, we calculated the age-standardized mean in sleep duration, timing, and consistency and the proportions meeting sleep recommendations on school and nonschool days from self-reported bedtimes and wake times. We conducted stratified analyses by gender, age, and family affluence group.

RESULTS

Adolescent sleep patterns varied cross-nationally. The average sleep duration ranged between 7:47 and 9:07 hours on school days and between 9:31 and 10:22 hours on nonschool days, and the proportion of adolescents meeting sleep recommendations ranged between 32% and 86% on school days and between 79% and 92% on nonschool days. Sleep patterns by gender and affluence groups were largely similar, but older adolescents slept less and went to bed later on school days than younger adolescents in all countries.

CONCLUSIONS

The sleep patterns of adolescents vary across countries and sociodemographic groups. Insufficient sleep on school days is common in many countries. Public health and policy efforts to promote healthy adolescent sleep are encouraged.

Social Jetlag and Its Association With Screen Time and Nighttime Texting Among Adolescents in Sweden: A Cross-Sectional Study

The discrepancy between social and biological clock due to sleep and wake up time difference across weekdays and weekends is referred as social jetlag. The overall aim of this study is to test whether there is an association between both screen time and nighttime texting and social jetlag among 13- to 15-year-old adolescents in Sweden. This study included a cross-sectional survey in which data were collected from all schools with grades 7 and 8 in four municipalities in southern Sweden. The sample consisted of 1518 students (72.7% response rate), among whom 50.7% were girls. Ages varied between 13 and 15 years (mean, 13.9; standard deviation (SD), 0.4). Social jetlag was defined as more than 2 h difference between bedtime and wake-up time on school days compared to weekends. The prevalence of social jetlag among this study population was 53.9%. After adjusting for age, sex, and economic status, the multivariate binary logistic regression analysis results showed that increased screen time (p < 0.001) and texting at night (p = 0.002) were significantly associated with social jetlag. Irregular bedtime and wake-up habits on school days and weekends are associated with nighttime texting and increased screen time. For future research, more focus should be given to identifying causality factors and gain an understanding of the effects of social jetlag, which will help in developing appropriate public health messages and intervention programs.

Interplay of chronotype and school timing predicts school performance

Most adolescents exhibit very late chronotypes and attend school early in the morning, a misalignment that can affect their health and psychological well-being. Here we examine how the interaction between the chronotype and school timing of an individual influences academic performance, studying a unique sample of 753 Argentinian students who were randomly assigned to start school in the morning (07:45), afternoon (12:40) or evening (17:20). Although chronotypes tend to align partially with class time, this effect is insufficient to fully account for the differences with school start time. We show that (1) for morning-attending students, early chronotypes perform better than late chronotypes in all school subjects, an effect that is largest for maths; (2) this effect vanishes for students who attend school in the afternoon; and (3) late chronotypes benefit from evening classes. Together, these results demonstrate that academic performance is improved when school times are better aligned with the biological rhythms of adolescents.

Chronotherapeutics: Recognizing the Importance of Timing Factors in the Treatment of Disease and Sleep Disorders

This review describes the characteristics of a number of pathologies, which are considered from the point of view of chronobiology, that is, the way in which biological processes are expressed throughout the 24-hour day. This perspective is a relatively new way of thinking about disease and additionally about how to treat diseases. It has called attention to the importance of not only the quantity of a drug that is administered but also when it is administered. In addition, the review presents an overview of the emerging clinical strategies known as chronotherapeutics, that is, the effects of the daily scheduling of drug administration and the consequences of the activity and efficacy of therapies that are applied in this manner. This article also reviews innovative ways in which physicians are applying time-specified drug treatment (chronopharmacology) for sleep disorders. Here, we present a systematic description of chronopharmacology as well as definitions of key terms that, we believe, will be helpful for newcomers to the field. It is hoped that greater awareness of this new perspective on pharmacology will promote its adoption by researchers and clinicians.

The role of sleep deprivation and circadian rhythm disruption as risk factors of Alzheimer's disease

Emerging evidence suggests that sleep deprivation (SD) and circadian rhythm disruption (CRD) may interact and increase the risk for the development of Alzheimer's disease (AD). This review inspects different pathophysiological aspects of SD and CRD, and shows that the two may impair the glymphatic-vascular-lymphatic clearance of brain macromolecules (e.g., β-amyloid and microtubule associated protein tau), increase local brain oxidative stress and diminish circulatory melatonin levels. Lastly, this review looks into the potential association between sleep and circadian rhythm with stress granule formation, which might be a new mechanism along the AD pathogenic pathway. In summary, SD and CRD is likely to be associated with a positive risk in developing Alzheimer's disease in humans.

Daily, weekly and annual patterns in children's accidental sport injuries

Details of serious injuries to children ≤16 yrs. of age that necessitated urgent surgical intervention by the Department of Pediatric Surgery of the University Hospital of Lausanne, Switzerland were recorded into a database registry. Some 15 110 entries listed the precise time of injury, and 3114 (20.6%) of these resulted from participating in sport-associated activities. Time-of-day, day-of-week and month-of-year differences in the total number of children's accidental sport injuries (CASI) were validated. Time-of-day patterns were substantiated for "All Sports", for both boys and girls 5-16 yrs. of age, with more boys than girls experiencing incidents at almost every clock hour. Moreover, they were substantiated for this age group for each of the six different considered individual and team CASI categories - Physical Exercises at School; Bicycle Riding; Roller Skating and Skateboarding; Snow Skiing, Sledding, and Tobogganing; Soccer; and Basketball - for which sample sizes were sufficiently large (n > 230) to perform statistical assessment by ANOVA, t-test and/or cosinor analyses. CASI happened primarily between 06:00 and 17:00 h and rarely evening or overnight. Features - specific clock-time and number of peaks and troughs - of the CASI daily curve pattern of the individual six sport categories differed somewhat; nonetheless, excess or greatest number of CASI typically happened between 12:00 and 14:00 h, even when summertime and other scheduled school and family vacation periods were taken into account. Time-of-day and day-of-week patterns in the boy/girl sex ratio were also validated, with midday and Friday/Saturday peaks, respectively. We hypothesize the prominent 24 h patterns of CASI of 5-16 yr. olds, in particular, are representative of a combination of several determinants. These include exogenous periodic and cyclic environmental and sociocultural phenomena, genetic sex-related traits, plus endogenous circadian cognitive and physiologic rhythms, with the common midday injury excess of many sport categories, at least in part, the consequence of the well-documented midday dip in attention and vigilance of children.

Association of health literacy and sleep problems with mental health of Chinese students in combined junior and senior high school

OBJECTIVES

The aim of this study was to examine the association between health literacy (HL) and sleep problems with mental health of Chinese students in combined junior and senior high school.

METHODS

A cross-sectional study was conducted among seven hundred and seventy-five students from a combined junior and senior high school in Shenyang on December 16, 2016. HL, sleep problems, anxiety symptoms and depressive symptoms were measured by self-reported validated instruments. Multiple logistic regression models were used to examine the association of HL and sleep problems with mental health problems.

RESULTS

The prevalence of anxiety symptoms and depressive symptoms was 24.6% and 45.2%, respectively. Low HL was significantly associated with anxiety symptoms (OR = 2.457, 95%CI: 1.493-4.045) and depressive symptoms (OR = 5.164, 95%CI: 3.233-8.250). Sleep problems were significantly positively correlated with anxiety symptoms (OR = 4.237, 95%CI: 2.831-6.341) and depressive symptoms (OR = 3.170, 95%CI: 2.084-4.823). The students who had sleep problems with low HL had the highest risks of anxiety symptoms (OR = 11.440, 95%CI: 5.564-23.520) and depressive symptoms (OR = 19.470, 95%CI: 8.143-46.558).

CONCLUSION

Our findings suggest that Chinese students in combined junior and senior high school who had sleep problems with low HL are at risk of exhibiting anxiety symptoms and depressive symptoms. Intervention programs of mental health problems should enhance HL level and improve sleep quality.

Altering Adolescents' Pre-Bedtime Phone Use to Achieve Better Sleep Health

Mobile phone use is often blamed for adolescent sleeping difficulties in the popular and scientific literature, with correlations observed between adolescents' mobile phone use and their bedtime. We aimed to obtain experimental evidence to support these causal claims. A within-subjects experiment (baseline, intervention) was conducted in adolescents' homes, to determine the effect of restricting adolescents' pre-bed mobile phone use on school night sleep habits. Following a baseline week, adolescents were given individualized phone stop times, 1 hour before bed for one school week. An online sleep diary was used to monitor bedtime, lights out time, sleep latency and total sleep. Sixty three adolescents (age range 14-18, M = 16.3, SD = 0.93yrs; 17%male) provided data. During one week of phone restriction, adolescents stopped using their phones earlier (80 min, p < .001), turned their lights off earlier (17 min, p = .01), and slept longer (21 min, p = .01). Participant recruitment was low (26%), indicating many adolescents lack motivation to negotiate changes to their evening phone use. Overall, there are potential benefits of restricted mobile phone use during the pre-sleep period, yet, future research is needed to identify non-technological interventions to increase adherence to phone restriction (e.g., motivational interviewing) or otherwise decrease pre-sleep arousal (e.g., cognitive strategies).

Development of a mobile application (App) to delineate "digital chronotype" and the effects of delayed chronotype by bedtime smartphone use

The widespread use and deep reach of smartphones motivate the use of mobile applications to continuously monitor the relationship between circadian system, individual sleep patterns, and environmental effects. We selected 61 adults with 14-day data from the "Know Addiction" database. We developed an algorithm to identify the "sleep time" based on the smartphone behaviors. The total daily smartphone use duration and smartphone use duration prior to sleep onset were identified respectively. We applied mediation analysis to investigate the effects of total daily smartphone use on sleep through pre-sleep use (PS). The results showed participants' averaged pre-sleep episodes within 1 h prior to sleep are 2.58. The duration of three pre-sleep uses (PS_1∼3) maybe a more representative index for smartphone use before sleep. Both total daily duration and the duration of the last three uses prior to sleep of smartphone use significantly delayed sleep onset, midpoint of sleep and reduced total sleep time. One hour of increased smartphone use daily, delays the circadian rhythm by 3.5 min, and reduced 5.5 min of total sleep time (TST). One hour of increased pre-sleep smartphone use delayed circadian rhythm by 1.7 min, and reduced 39 s of TST. The mediation effects of PS_1∼3 significantly impacted on these three sleep indicators. PS_1∼3 accounted for 14.3% of total daily duration, but the proportion mediated of delayed circadian rhythm was 44.0%. We presented "digital chronotype" with an automatic system that can collect high temporal resolution data from naturalistic settings with high ecological validity. Smartphone screen time, mainly mediated by pre-sleep use, delayed the circadian rhythm and reduced the total sleep time.