Do later school start times improve adolescents' sleep and substance use? A quasi-experimental study

OBJECTIVE

A later school start time policy has been recommended as a solution to adolescents' sleep deprivation. We estimated the impacts of later school start times on adolescents' sleep and substance use by leveraging a quasi-experiment in which school start time was delayed in some regions in South Korea.

METHODS

A later school start time policy was implemented in 2014 and 2015, which delayed school start times by approximately 30-90 minutes. We applied difference-in-differences and event-study designs to longitudinal data on a nationally representative cohort of adolescents from 2010 to 2015, which annually tracked sleep and substance use of 1133 adolescents from grade 7 through grade 12.

RESULTS

The adoption of a later school start time policy was initially associated with a 19-minute increase in sleep duration (95% CI, 5.52 to 32.04), driven by a delayed wake time and consistent bedtime. The policy was also associated with statistically significant reductions in monthly smoking and drinking frequencies. However, approximately a year after implementation, the observed increase in sleep duration shrank to 7  minutes (95% CI, -12.60 to 25.86) and became statistically nonsignificant. Similarly, the observed reduction in smoking and drinking was attenuated a year after.

CONCLUSIONS

Our findings suggest that policies that increase sleep in adolescents may have positive effects on health behaviors, but additional efforts may be required to sustain positive impacts over time. Physicians and education and health policymakers should consider the long-term effects of later school start times on adolescent health and well-being.

Recipe for fatigue: sleep, work patterns, and well-being of galley workers on surface ships of the US Navy

Study Objectives

The purpose of the study was to compare the fatigue levels, work/rest patterns, health-related behaviors, and well-being of galley workers with other sailors on US Navy ships while underway.

Methods

Analysis was based on a retrospective comparison of data from 3 fit-for-duty groups of sailors: 67 galley workers, 192 non-watchstanders, and 466 watchstanders. Participants completed questionnaires (Epworth Sleepiness Scale [ESS], Insomnia Severity Index [ISI], Pittsburgh Sleep Quality Index [PSQI], and Profile of Mood States [POMS]) and activity logs, and wore actigraphs.

Results

Galley workers slept MD = 6.57 (IQR = 1.42) h/d and worked MD = 12.8 (IQR = 2.42) h/d. Approximately 84% of the galley workers were classified as poor sleepers, ~57% reported having excessive daytime sleepiness (EDS), and ~38% reported elevated insomnia symptoms. Compared to non-watchstanders, galley workers had worse scores on POMS (total mood disturbance, tension-anxiety, depression, anger-hostility, fatigue, and confusion-bewilderment), ESS, ISI, and PSQI. Compared to non-watchstanders, galley workers had a higher risk for symptoms of EDS (75%), symptoms of clinically relevant insomnia (126%), and for being classified as poor sleepers (27%). Galley workers slept less and worked on average 2 h/d more than non-watchstanders. Compared to watchstanders, galley workers had worse ESS, ISI, and anger-hostility scores. More watchstanders napped compared to galley workers.

Conclusions

Although they are considered day workers, the sleep patterns, fatigue levels, and mood of galley workers are comparable to, or worse than, watchstanders or other non-watchstanders. To ameliorate the effects of long work hours on sailor well-being, ship leadership should consider adopting strategies to improve galley workers' well-being.

Adolescent chronic sleep restriction promotes alcohol drinking in adulthood: evidence from epidemiological and preclinical data

Epidemiological investigations have indicated that insufficient sleep is prevalent among adolescents, posing a globally underestimated health risk. Sleep fragmentation and sleep loss during adolescence have been linked to concurrent emotional dysregulation and an increase in impulsive, risk-taking behaviors, including a higher likelihood of substance abuse. Among the most widely used substances, alcohol stands as the primary risk factor for deaths and disability among individuals aged 15-49 worldwide. While the association between sleep loss and alcohol consumption during adolescence is well documented, the extent to which prior exposure to sleep loss in adolescence contributes to heightened alcohol use later in adulthood remains less clearly delineated. Here, we analyzed longitudinal epidemiological data spanning 9 years, from adolescence to adulthood, including 5497 participants of the Avon Longitudinal Study of Parents And Children cohort. Sleep and alcohol measures collected from interviews and questionnaires at 15 and 24 years of age were analyzed with multivariable linear regression and a cross-lagged autoregressive path model. Additionally, we employed a controlled preclinical experimental setting to investigate the causal relationship underlying the associations found in the human study and to assess comorbid behavioral alterations. Preclinical data were collected by sleep restricting Marchigian Sardinian alcohol preferring rats (msP, n=40) during adolescence and measuring voluntary alcohol drinking concurrently and in adulthood. Polysomnography was used to validate the efficacy of the sleep restriction procedure. Behavioral tests were used to assess anxiety, risky behavior, and despair. In humans, after adjusting for covariates, we found a cross-sectional association between all sleep parameters and alcohol consumption at 15 years of age but not at 24 years. Notably, alcohol consumption (Alcohol Use Disorder Identification Test for Consumption) at 24 years was predicted by insufficient sleep at 15 years whilst alcohol drinking at 15 years could not predict sleep problems at 24. In msP rats, adolescent chronic sleep restriction escalated alcohol consumption and led to increased propensity for risk-taking behavior in adolescence and adulthood. Our findings demonstrate that adolescent insufficient sleep causally contributes to higher adult alcohol consumption, potentially by promoting risky behavior.

The Impact of Delayed School Start Times During COVID-19 on Academic Performance: A Longitudinal Naturalistic Study in Italian High Schools

Background

Delaying school start times has been proposed as a potential solution to address chronic sleep curtailment among adolescents and its negative consequences on their physical and mental well-being. This study investigates the impact of delayed school start times due to the COVID-19 pandemic on academic achievement.

Subjects and Methods

Two separate observational studies were conducted involving high school students from the first/second year (n=232) (Study 1) and from the final year (n=39) (Study 2). Multivariate Analyses of Covariance were performed to assess for statistical differences in academic performance (ie, global, humanistic, and scientific performance) and absenteeism (ie, number of school absences). Two main factors were considered: "school start time" (ie, standard-8:00 AM vs late-9:40 AM) and "time interval" (ie, first academic semester vs second academic semester), controlling for the school year (Study 1) and circadian preference (Study 2).

Results

Delaying school start times was positively associated with better academic performance in scientific subjects among first/second-year students (F1,229=6.083, p=0.026) and global academic performance among last-year students (F1,35=4.522, p=0.041). Furthermore, first/second-year students significantly increased their school achievement (F1,229>29.423, p<0.001) and school absences (F1,229=66.160, p<0.001) during the second semester of the academic year. No significant effect of "school start time" on school attendance was observed. Additionally, circadian preference was found to be a significant covariate among last-year students, with early chronotypes exhibiting better academic performance (r>0.369, p<0.025).

Conclusion

These findings confirm past evidence about the beneficial effects of delayed school start times on academic outcomes, with the additional advantage of observing them within a natural context that emerged during the pandemic. Further research is needed to explore the phenomenon more systematically and take into account the broader implications of implementing this change.

Development of evening sleep homeostatic pressure in early adolescent boys

The physiological processes governing sleep regulation show maturational changes during adolescent development. To date, data are available to specify when delays in circadian timing occur; however, no longitudinal data exist to characterize the maturation of the accumulation of sleep pressure across the evening. The aim of this longitudinal study was to test whether this change in evening sleep propensity can be identified during early adolescence. Twenty pre-pubescent boys' (Mage = 10.3, SD = 0.4 years) evening sleep homeostats were assessed using a series of sleep latency tests every hour (7:30 p.m. to 3:30 a.m.) at 6-month intervals across four waves. While results revealed shorter sleep onset latencies with increasing wakefulness (p < .001), this effect was not moderated by study wave (p = .79). Evening sleep propensity thus appears to remain stable in boys during early adolescence. Future studies should expand upon these findings by using larger samples of girls as well as boys across an extended age range during the teenage years.

Impact of delaying high school start times on weight and related behaviors - the START study

In the US, few adolescents get adequate school night sleep, largely due to early school start times. In the START study we aimed to test the following hypothesis: That following the implementation of later high school start times students have lesser longitudinal increases in body mass index (BMI) and shift to more healthful weight-related behaviors relative to students attending schools that retain early start times. The study enrolled a cohort of students (n = 2426) in five high schools in the Twin Cities, MN metro. Heights and weights were measured objectively, and surveys were administered annually from 9th through 11th grades (2016-2018). All study schools started early (either 7:30 am or 7:45 am) at baseline (2016). At follow-up 1 (2017) and continuing through follow-up 2 (2018), two schools delayed their start times by 50-65 min, while three comparison schools started at 7:30 am throughout the observation period. Using a difference-in-differences natural experiment design, we estimated differences in changes in BMI and weight-related behaviors over time between policy change and comparison schools. Students' BMIs increased in parallel in both policy change and comparison schools over time. However relative to changes in comparison schools after the start time shift, students in policy change schools had a modestly more healthful profile of weight-related behaviors - for instance they had a relatively greater probability of eating breakfast, having supper with their family, getting more activity, eating fast food less frequently, and eating vegetables daily. Later start times could be a durable, population-wide strategy that promotes healthful weight behaviors.

Effect of Sleep Changes on Health-Related Quality of Life in Healthy Children: A Secondary Analysis of the DREAM Crossover Trial

IMPORTANCE

Little is known regarding the effect of poor sleep on health-related quality of life (HRQOL) in healthy children.

OBJECTIVE

To determine the effect of induced mild sleep deprivation on HRQOL in children without major sleep issues.

DESIGN, SETTING, AND PARTICIPANTS

This prespecified secondary analysis focused on HRQOL, a secondary outcome of the Daily Rest, Eating, and Activity Monitoring (DREAM) randomized crossover trial of children who underwent alternating weeks of sleep restriction and sleep extension and a 1-week washout in between. The DREAM trial intervention was administered at participants' homes between October 2018 and March 2020. Participants were 100 children aged 8 to 12 years who lived in Dunedin, New Zealand; had no underlying medical conditions; and had parent- or guardian-reported normal sleep (8-11 hours/night). Data were analyzed between July 4 and September 1, 2022.

INTERVENTIONS

Bedtimes were manipulated to be 1 hour later (sleep restriction) and 1 hour earlier (sleep extension) than usual for 1 week each. Wake times were unchanged.

MAIN OUTCOMES AND MEASURES

All outcome measures were assessed during both intervention weeks. Sleep timing and duration were assessed using 7-night actigraphy. Children and parents rated the child's sleep disturbances (night) and impairment (day) using the 8-item Pediatric Sleep Disturbance and 8-item Sleep-Related Impairment scales of the Patient-Reported Outcomes Measurement Information System questionnaire. Child-reported HRQOL was assessed using the 27-item KIDSCREEN questionnaire with 5 subscale scores and a total score. Both questionnaires assessed the past 7 days at the end of each intervention week. Data were presented as mean differences and 95% CIs between the sleep restriction and extension weeks and were analyzed using intention to treat and an a priori difference in sleep of at least 30 minutes per night.

RESULTS

The final sample comprised 100 children (52 girls [52%]; mean [SD] age, 10.3 [1.4] years). During the sleep restriction week, children went to sleep 64 (95% CI, 58-70) minutes later, and sleep offset (wake time) was 18 (95% CI, 13-24) minutes later, meaning that children received 39 (95% CI, 32-46) minutes less of total sleep per night compared with the sleep extension week in which the total sleep time was 71 (95% CI, 64-78) minutes less in the per-protocol sample analysis. Both parents and children reported significantly less sleep disturbance at night but greater sleep impairment during the day with sleep restriction. Significant standardized reductions in physical well-being (standardized mean difference [SMD], -0.28; 95% CI, -0.49 to -0.08), coping in a school environment (SMD, -0.26; 95% CI, -0.42 to -0.09), and total HRQOL score (SMD, -0.21; 95% CI, -0.34 to -0.08) were reported by children during sleep restriction, with an additional reduction in social and peer support (SMD, -0.24; 95% CI, -0.47 to -0.01) in the per-protocol sample analysis.

CONCLUSIONS AND RELEVANCE

Results of this secondary analysis of the DREAM trial indicated that even 39 minutes less of sleep per night for 1 week significantly reduced several facets of HRQOL in children. This finding shows that ensuring children receive sufficient good-quality sleep is an important child health issue.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12618001671257.

Sleep variability over a 2-week period is associated with restfulness and intrinsic limbic network connectivity in adolescents

STUDY OBJECTIVES

Sleep duration and intraindividual variability in sleep duration undergo substantial changes in adolescence and impact brain and behavioral functioning. Although experimental work has linked acute sleep deprivation to heightened limbic responding and reduced regulatory control, there is limited understanding of how variability in sleep patterns might interact with sleep duration to influence adolescent functioning. This is important for optimal balancing of length and consistency of sleep. Here, we investigated how objective indices of sleep duration and variability relate to stress, restfulness, and intrinsic limbic network functioning in adolescents.

METHODS

A sample of 101 adolescents ages 14-18 reported their stressors, after which they wore wrist actigraph watches to monitor their sleep and rated their restfulness every morning over a 2-week period. They also completed a resting-state fMRI scan.

RESULTS

Adolescents reporting more stress experienced shorter sleep duration and greater sleep variability over the 2-week period. Longer nightly sleep duration was linked to feeling more rested the next morning, but this effect was reduced in adolescents with high cumulative sleep variability. Sleep variability showed both linear and quadratic effects on limbic connectivity: adolescents with high sleep variability exhibited more connectivity within the limbic network and less connectivity between the limbic and frontoparietal networks than their peers, effects which became stronger once variability exceeded an hour.

CONCLUSIONS

Results suggest that cumulative sleep variability is related to stress and limbic network connectivity and shows interactive effects with sleep duration, highlighting the importance of balancing length and consistency of sleep for optimal functioning in adolescence.

[Sleepiness among adolescents: etiology and multiple consequences]

Over the past century a dramatic decline in sleep duration among adolescents, such as more than one hour of sleep loss per night, has been reported. A debt in sleep duration could lead to sleep deprivation, a major risk factor associated with daytime sleepiness. Sleepiness refers to the inability to maintain an adequate level of alertness during the day which may result in more or less being able to control falling asleep at inappropriate times. This literature review updates on sleepiness regarding its characteristics, etiology and consequences on adolescents. Studies revealed that from 25 % to 78 % of adolescents had reported sleepiness. Its manifestations may include heavy lids, yawns, difficulties to concentrate and emotional irritability. In addition, while it is recommended that adolescents under 18 years-old should sleep from eight to ten hours a night, only 63 % of them actually do so. The etiology of sleep deprivation and sleepiness in this population can be explained by various biological and societal factors. First, the sleep-wake cycle of adolescents shows a biological shift from the beginning of pubertal maturation, described as a perfect storm. It refers to a social jetlag by going to sleep and waking up later and accumulating a sleep debt during weekdays which they try to reimburse during weekends. This phenomenon can be explained by physiological changes such as a slower accumulation of sleep pressure. In addition to this perfect storm, environmental and societal factors contribute to the social jetlag and reduce sleep duration in adolescents. Screen exposure before bedtime can delay sleep and wake onset, which is a risk factor for sleeping debt. Substance use such as caffeine, cigarettes or electronic vaporizer, ADHD or freely available medication, alcohol, cannabis use or drug consumption could further disrupt sleep-wake cycle by stimulating, depressing or otherwise disrupting the central nervous system. Early, before 8:30 am, class start times have been associated with chronic sleep deprivation, higher level of sleepiness and delayed melatonin peak secretion. Adolescents working or doing extracurricular occupations for more than 20hours a week are more at risk for reduced sleep duration and sleepiness. Parental supervision about sleep during the weekdays were associated with more appropriate bedtime. Adolescents from low socio-demographic characteristics and from minority ethnic groups have reported displaying a shorter sleep duration. Finally, sleep disorders of a physiological origin such as narcolepsy, sleep apnea or restless legs syndrome, may explain the sleep deprivation and sleepiness. Sleep deprivation and sleepiness in adolescents have consequences on their health. Cognitive functioning, such as problem solving, attention or memory, as well as school performance, can be compromised by sleep deprivation and sleepiness. At the psychological level, adolescents reporting sleepiness are more prone to display mental health problems: associations were found between sleepiness and subjective perception of depression, anxiety, somatic complaints as well as with antisocial behaviors. Finally, 68 % of 16 year-old adolescents reported they drove a car, and the reported sleepiness could lead to road accidents due to reduced attentional functioning, reaction time and decision-making abilities. In the United-States, from 7 % to 16.5 % of deadly accidents were related to driving while drowsy. Highlighting etiology and problems associated with sleep deprivation and sleepiness in adolescents could guide researchers and clinicians towards the development of possible interventions. Public health measures and knowledge transfer programs regarding modifiable psychosocial and societal factors associated with sleep-wake bioregulation could increase awareness in parents as well as in political and societal decision makers.

What's "app"-ning to adolescent sleep? Links between device, app use, and sleep outcomes

This study investigated the associations between adolescent evening use of technology devices and apps, night time sleep, and daytime sleepiness. Participants were 711 adolescents aged 12-18 years old (46% Female, M_age = 15.1, SD = 1.2). Time spent using technology devices and apps in the hour before bed, and in bed before sleep onset, was self-reported. Participants additionally completed a questionnaire about their sleep on school nights and next day sleepiness. In the hour before bed, 30 min of phone use was associated with a 9-min delay in bedtimes. Thirty minutes spent using laptops, gaming consoles, and watching YouTube was associated with later lights out times of 9 min, ∼16 min and ∼11 min respectively, while watching TV was associated with a 9 min earlier lights out times. Using gaming consoles and watching YouTube were associated with greater odds of receiving insufficient sleep (≤7 h TST). In bed before sleep onset, 30 min spent using laptops, phones, iPad/tablets, and watching YouTube were linked with later lights out times of ∼7 min for phones and laptops, 9 min for iPad/tablets, and ∼13 min for YouTube. Watching Netflix was associated with greater daytime sleepiness. YouTube at this time point was associated with increased odds of sleeping ≤7 h on school nights. Adolescents are engaging with a wide range of technology devices and apps in the evenings. However, certain devices and apps (e.g., phones, laptops, gaming and YouTube) might lead to more negative sleep outcomes for adolescents on school nights compared to others.

Wi-Fi off, devices out: do parent-set technology rules play a role in adolescent sleep?

There is limited evidence surrounding the relationship between parent-set technology rules and adolescent sleep. This study had two aims: 1) to investigate the relationship between presence of and compliance to parent-set technology rules and adolescent sleep outcomes and daytime sleepiness; 2) to investigate if compliance, non-compliance, or the absence of rules could moderate the relationship between Fear of Missing Out (FoMO) and Bedtime Procrastination (BtP) on sleep outcomes and daytime sleepiness. A total of 711 adolescents aged 12–18 years old (46% Female, M_age = 15.1, SD = 1.2) were recruited through secondary schools in South Australia. Participants completed a survey containing self-report measures about their sleep, daytime sleepiness, FoMO, BtP, the presence/absence of technology rules in their house, and their compliance to these rules. The study design was cross sectional. Results indicated that the presence of a parent-set technology rule was associated with earlier bedtimes regardless of compliance. Earlier lights out times and increased sleep duration were observed in adolescents who always complied to their rules compared to those who did not comply or did not have parent-set technology rules. BtP and FoMO were associated with later bedtimes, later lights out times, longer sleep onset latency, shorter sleep duration, and more daytime sleepiness. However, parent-set rules did not moderate the links between BtP/FoMO and adolescent sleep. Whilst longitudinal investigations are warranted to examine the directionality of these relationships, the present study suggests that parent-set technology rules may play an important role in protecting adolescent sleep.

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Having a parent set technology rule was associated with earlier bedtimes.

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Only consistent compliance was linked to earlier lights out times and longer TST.

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Noncompliance or the absence of rules was not linked to these sleep outcomes.

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Bedtime procrastination and Fear of Missing Out were linked with poorer sleep outcomes.

Adolescent sleep myths: Identifying false beliefs that impact adolescent sleep and well-being

OBJECTIVE

Commonly held beliefs about sleep unsupported by scientific evidence (ie, myths) among adolescents and their parents/caregivers may adversely influence sleep-related attitudes and behaviors among adolescents. Thus, identifying such myths with the goal of developing effective evidence-based counter-messages has the potential to improve sleep health in adolescents.

METHOD

We identified myths with a panel of adolescent sleep health experts (n = 12) using the Delphi method in three sequential steps: (1) focus groups; (2) online discussion; and (3) closed-ended questionnaires with which the experts rated myths on: (1) falseness and (2) public health significance using 5-point Likert scales ranging from 1 (not at all false/important for public health) to 5 (extremely false/important for public health). Next, we explored the prevalence of the myths among a demographically diverse sample of parents/caregivers of adolescents in the United States. Finally, we report the counterevidence to refute each myth.

RESULTS

Ten myths about adolescent sleep were identified by the experts using the Delphi method. The most prevalent myths were the beliefs that (1) "Going to bed and waking up late on the weekends is no big deal for adolescents, as long as they get enough sleep during that time," reported by 74% of parents/caregivers; (2) "If school starts later, adolescents will stay up that much later," reported by 69% of parents/caregivers; and (3) "Melatonin supplements are safe for adolescents because they are natural," reported by 66% of parents/caregivers.

CONCLUSION

Parents/caregivers have the potential to serve as sleep health advocates for their adolescent and support their adolescent's sleep health behaviors. Our study found that many parents/caregivers endorse myths about adolescent sleep that may hinder their ability to support their adolescent's sleep health. Future research may explore methods for promoting evidence-based beliefs about adolescent sleep among parents/caregivers.

Sleep troubles in adolescence relate to future initiation of ENDS USE: A longitudinal cohort design using the PATH study waves 4.5–5 (2017–2019)

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First longitudinal study on the association between sleep trouble and ENDS use.

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Past year sleep trouble increased risk of initiating ENDS use in following year.

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Healthy sleep serves as a protective factor against ENDS uptake for youth.

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Nearly half of youths aged 12–17, experienced sleep troubles during wave 4.5.

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Sleep classes for youth/delayed school start times may help deter future ENDS use.

In a recent study, we demonstrated a relationship between self-reported sleep deprivation and youth susceptibility to initiate electronic nicotine delivery systems (ENDS) use; however, we were hampered by cross-sectional data. This study builds on our previous work by performing secondary analysis using the nationally representative Population Assessment of Tobacco and Health study datasets from wave 4.5 (2017–2018) and wave 5 (2018–2019) among respondents aged 12–17. Using a longitudinal cohort design, we assessed the extent self-reported sleep troubles at wave 4.5 related to transition from never-to-ever ENDS use by wave 5. We assessed youth who reported never having used any type of tobacco previously and who reported not using alcohol or other illicit substances the previous year. We ran four Poisson regression models on the dependent variable never-to-ever ENDS users at wave 5 and self-reported sleep troubles in the past year at wave 4.5. We controlled for demographic and sociographic factors and, in our final model, tobacco availability in home, exposure to ENDS advertising on social media, past year anxiety, depression, body mass index, physical activity, close friends that use ENDS, perceived harm of ENDS, school performance, sensation seeking, and the susceptibility of youth to initiate ENDS. Even when controlling for these factors, sleep troubles at wave 4.5 significantly and positively related to ENDS initiation by wave 5 (Past year sleep trouble: RR = 1.48 95 % CI = [1.14–1.93]). This key and novel finding has important implications for preventing youth ENDS use via protective self-care and social-environmental approaches.

The Role of Sleep Patterns from Childhood to Adolescence in Vigilant Attention

Only a few studies addressed age-related changes from childhood to adolescence in sleep patterns, sleepiness, and attention. Vigilant attention plays a key role in cognitive performance. While its nature and course have been investigated broadly among adults, only limited research has been conducted on its development between childhood and adolescence. The main aim of the current study was to replicate previous findings about the effects of sleep loss on age-related changes in vigilance attention performance and sleepiness in a natural setting. A total of 104 children and adolescents (46 children aged 6-9 and 58 adolescents aged 13-19) wore an actigraph for a continuous five to seven nights, including weekdays and weekends. Subjective sleepiness (Karolinska Sleepiness Scale) and a Psychomotor Vigilance Test (PVT-B) were measured on two school days and one non-school day. Findings showed that PVT-B performance differed by age group, with adolescents outperforming children in PVT-B measures in spite of their elevated subjective sleepiness. Adolescents demonstrated less sleep time and increased sleepiness. Although PVT-B performance was better among adolescents, a within-subject analysis revealed that adolescents performed better on PVT measures on weekends than on weekdays. The results are discussed in relation to the synaptic elimination model.

Associations among sleep, hematologic profile, and aerobic and anerobic capacity of young swimmers: A complex network approach

Although the link between sleep and hematological parameters is well-described, it is unclear how this integration affects the swimmer’s performance. The parameters derived from the non-invasive critical velocity protocol have been extensively used to evaluate these athletes, especially the aerobic capacity (critical velocity—CV) and the anaerobic work capacity (AWC). Thus, this study applied the complex network model to verify the influence of sleep and hematological variables on the CV and AWC of young swimmers. Thirty-eight swimmers (male, n = 20; female, n = 18) completed five experimental evaluations. Initially, the athletes attended the laboratory facilities for venous blood collection, anthropometric measurements, and application of sleep questionnaires. Over the 4 subsequent days, athletes performed randomized maximal efforts on distances of 100, 200, 400, and 800-m. The aerobic and anerobic parameters were determined by linear function between distance vs. time, where CV relates to the slope of regression and AWC to y-intercept. Weighted but untargeted networks were generated based on significant (p < 0.05) correlations among variables regardless of the correlation coefficient. Betweenness and eigenvector metrics were used to highlight the more important nodes inside the complex network. Regardless of the centrality metric, basophils and red blood cells appeared as influential nodes in the networks with AWC or CV as targets. The role of other hematologic components was also revealed in these metrics, along with sleep total time. Overall, these results trigger new discussion on the influence of sleep and hematologic profile on the swimmer’s performance, and the relationships presented by this targeted complex network can be an important tool throughout the athlete’s development.

Characteristics of Sleep Patterns in Adolescents: Comparisons between Saudi Arabia and the UK

There are concerns regarding sleep deprivation among adolescents, especially with mounting evidence for the importance of sleep during puberty, and its effects on health and families. The present study aimed to characterise sleep in typical development (TD) adolescents in Saudi Arabia, and compare their sleep profiles to TD adolescents in the UK, to evaluate sleep patterns in adolescents in Saudi Arabia, and to examine the relationship between sleep patterns and the use of social media in both groups. Findings from the current study reported a shorter sleep duration for the Saudi Arabia group than in previous studies and the UK group, which may be attributed to the lack of sleep hygiene practised in Saudi Arabia. Multiple analysis of variance results found significant differences in daytime sleepiness (p < 0.001) and a preference for morningness/eveningness (p < 0.001) between Saudia Arabia and UK adolescents. Statistically significant negative correlations (p > 0.05) between the duration of social media usage and sleep duration were found in both the Saudi Arabia and UK adolescents, where a lower number of sleep hours was observed with a higher duration of social media use. This study fills a gap in the research of sleep in Saudi Arabia in adolescents, and offers important insights on the comparison in sleep habits between Saudi Arabia and UK adolescents.

Sleep's role in the development and resolution of adolescent depression

Two adolescent mental health fields - sleep and depression - have advanced largely in parallel until about four years ago. Although sleep problems have been thought to be a symptom of adolescent depression, emerging evidence suggests that sleep difficulties arise before depression does. In this Review, we describe how the combination of adolescent sleep biology and psychology uniquely predispose adolescents to develop depression. We describe multiple pathways and contributors, including a delayed circadian rhythm, restricted sleep duration and greater opportunity for repetitive negative thinking while waiting for sleep. We match each contributor with evidence-based sleep interventions, including bright light therapy, exogenous melatonin and cognitive-behaviour therapy techniques. Such treatments improve sleep and alleviate depression symptoms, highlighting the utility of sleep treatment for comorbid disorders experienced by adolescents.

Staying vigilant during recurrent sleep restriction: dose-response effects of time-in-bed and benefits of daytime napping

Study Objectives

We characterized vigilance deterioration with increasing time-on-task (ToT) during recurrent sleep restriction of different extents on simulated weekdays and recovery sleep on weekends, and tested the effectiveness of afternoon napping in ameliorating ToT-related deficits.

Methods

In the Need for Sleep studies, 194 adolescents (age = 15–19 years) underwent two baseline nights of 9-h time-in-bed (TIB), followed by two cycles of weekday manipulation nights and weekend recovery nights (9-h TIB). They were allocated 9 h, 8 h, 6.5 h, or 5 h of TIB for nocturnal sleep on weekdays. Three additional groups with 5 h or 6.5 h TIB were given an afternoon nap opportunity (5 h + 1 h, 5 h + 1.5 h, and 6.5 h + 1.5 h). ToT effects were quantified by performance change from the first 2 min to the last 2 min in a 10-min Psychomotor Vigilance Task administered daily.

Results

The 9 h and the 8 h groups showed comparable ToT effects that remained at baseline levels throughout the protocol. ToT-related deficits were greater among the 5 h and the 6.5 h groups, increased prominently in the second week of sleep restriction despite partial recuperation during the intervening recovery period and diverged between these two groups from the fifth sleep-restricted night. Daytime napping attenuated ToT effects when nocturnal sleep restriction was severe (i.e. 5-h TIB/night), and held steady at baseline levels for a milder dose of nocturnal sleep restriction when total TIB across 24 h was within the age-specific recommended sleep duration (i.e. 6.5 h + 1.5 h).

Conclusions

Reducing TIB beyond the recommended duration significantly increases ToT-associated vigilance impairment, particularly during recurrent periods of sleep restriction. Daytime napping is effective in ameliorating such decrement.

Clinical Trial Registration

NCT02838095, NCT03333512, and NCT04044885.

Sleep deprivation and adolescent susceptibility to vaping in the United States

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Adolescent sleep deprivation is associated with susceptibility to ENDS use.

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Less than 6 h sleep relates to higher perceived likelihoods of trying ENDS.

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ENDS prevention efforts may benefit by incorporating sleep hygiene measures.

Sleep deprivation may be a contributing factor to adolescents’ willingness to experiment with substance use, including electronic nicotine devices (ENDS). While it is generally accepted that nicotine has a negative overall effect on sleep, no studies have yet explored whether sleep deprivation may contribute to adolescents’ initiation of ENDS use. The purpose of this study is to explore whether sleep deprivation is associated with adolescents’ self-reported susceptibility to initiating ENDS use in the next month. Respondents were 1,100 adolescents aged 13–17 across the United States who participated in the Vaping Attitudes Youth Perspectives Survey (VAYPS). We used logistic regression to examine cross-sectional associations between self-reported average sleep duration and self-reported likelihood of trying ENDS in the future. Results of the three logistic regression models show that adolescents who reported getting less than six hours of sleep per night were associated with greater odds of reporting any likelihood to try a vape in the next 30 days even when controlling for demographics and potential confounders (<6hrs sleep: OR = 2.63, 95% CI 1.30–5.31). Future research on the association between sleep deprivation and ENDS use among adolescents will benefit from using longitudinal approaches to better understand causality.

Instruments For Assessment Of Excessive Daytime Sleepiness In Brazilian Children And Adolescents: Systematic Review

Objective:

To systematically review the literature on the instruments used to assess excessive daytime sleepiness (EDS) in Brazilian children and adolescents.

Data source:

A systematic review of the literature was performed in the databases MEDLINE PubMed, Scopus, Web of Science, LILACS, Scielo and SPORTDiscus, with no time limit for searches. The eligibility criteria were studies published in English and Portuguese, original articles that used questionnaires to assess EDS and whose sample consisted of Brazilian children and/or adolescents. As search strategy, the following terms were combined with Boolean operators “OR” and/or “AND”: drowsiness, disorders of excessive somnolence, excessive daytime sleepiness, day sleepiness, midday sleepiness, daytime sleepiness, adolescents, Brazil, Brazilian adolescents, and children.

Data synthesis:

Sixteen articles were selected, in which nine different instruments were applied to 8.240 children and adolescents from the South, Southeast, Midwest and Northeast regions of Brazil. The mean of methodological quality of studies was 16.1±1.9 points. The instruments most frequently used were the Pediatric Daytime Sleepiness Scale (PDSS) and Karolinska Sleepiness Scale (KSS), but only PDSS was shown reliable to assess EDS in Brazilian children and adolescents.

Conclusions:

The PDSS was the only instrument considered reliable to assess EDS in Brazilian children and adolescents. Further research on EDS in children and adolescents are suggested to perform the validation of other instruments for Brazil and present internal consistency values.

Understanding Sleep-Wake Behavior in Late Chronotype Adolescents: The Role of Circadian Phase, Sleep Timing, and Sleep Propensity

BACKGROUND

Adolescents with a late chronotype are at greater risk for mood disorders, risk-taking behaviors, school absenteeism, and lower academic achievement. As there are multiple causes for late chronotype, the field lacks studies on the relationship between mood, circadian phase, and phase angle of entrainment in late chronotype adolescents. Three objectives guide this explorative study: (1) to describe sleep, circadian phase, and phase angle of entrainment in late chronotype adolescents, (2) to explore how different levels of lateness are associated with sleep quality, sleep propensity, and mood, and (3) to investigate the influence of circadian phase on bedtime choice and sleep duration.

METHODS

Baseline data from 19 male adolescents (M = 16.4 ± 1.0 yrs), who were part of a larger intervention trial, were analyzed. Chronotype was measured with the Munich Chronotype Questionnaire, circadian timing via dim light melatonin onset (DLMO), and sleep habits with a 7-day sleep log. Further questionnaires assessed daytime sleepiness, sleep quality, and mood. Evening sleepiness and sustained attention were used as a proxy for evening sleep propensity.

RESULTS

On school nights, sleep duration averaged 7.78 h (±1.65), and 9.00 h (±1.42) on weekend nights. Mean DLMO was observed at 23.13 h (± 1.65), with a weekend phase angle of entrainment of 2.48 h. Regression fittings revealed a tendency for shorter phase angles with delayed DLMOs. Further analysis with chronotype subgroups revealed that this was only true for light and moderate late types, whereas extreme late types showed wide phase angles. Even though daytime sleepiness and sleep duration did not differ between subgroups, mood and sleep quality declined as lateness increased. Extreme late chronotypes experienced higher evening sleepiness, while slight late chronotypes showed higher evening attention. Chronotype but not DLMO predicted bedtime on school- and particularly weekend-nights.

CONCLUSIONS

Our findings suggest that with increasing lateness, the likelihood of experiencing poor sleep quality and mood disorders increases. As DLMO did not predict bedtime, our data indicate that the factors contributing to a late chronotype are versatile and complex, particularly for extreme late types. Further studies involving a larger and gender-balanced sample are needed to confirm findings.

Impaired Vigilant Attention Partly Accounts for Inhibition Control Deficits After Total Sleep Deprivation and Partial Sleep Restriction

PURPOSE

Sleep loss impairs a range of neurobehavioral functions, particularly vigilant attention and arousal. However, the detrimental effects of sleep deprivation on inhibition control and its relationship to vigilant attention impairments remain unclear. This study examined the extent to which vigilant attention deficits contribute to inhibition control performance after one night of total sleep deprivation (TSD) and two nights of partial sleep restriction (PSR).

PARTICIPANTS AND METHODS

We analyzed data from N = 49 participants in a one-night of TSD experiment, N=16 participants in a control experiment without sleep loss, and N = 16 participants in a two-nights of PSR experiment (time in bed, TIB = 6 h for each night). Throughout waking periods in each condition, participants completed the psychomotor vigilance test (PVT), which measures vigilant attention, and the Go/No-Go task, which measures inhibition control.

RESULTS

After TSD and PSR, participants displayed significantly slower reaction times (RT) and more lapses in PVT performance, as well as slower Go RT and more errors of omission during the Go/No-Go task. PVT deficits accounted for 18.0% of the change in Go RT and 12.4% of the change in errors of omission in the TSD study, and 23.7% of the change in Go RT and 20.3% of the change in errors of omission in the PSR study.

CONCLUSION

Both TSD and PSR impaired inhibition control during the Go/No-Go task, which can be partly accounted for by vigilant attention deficits during the PVT. These findings support the key role of vigilant attention in maintaining overall neurobehavioral function after sleep loss.

What Is “Chronic” in “Chronic Sleep Reduction” and What Are Its Consequences? A Systematic Scoping Review of the Literature

Purpose of Review

In this scoping review, we aimed to (1) provide an overview of chronic sleep reduction by systematically reviewing the existing literature (limited to systematic reviews and meta-analyses), (2) investigate the evidence of the effects of short sleep duration on daytime functioning, and (3) identify research gaps in this field.

Recent Findings

The results showed that (1) clear definitions of chronicity of sleep reduction are lacking—none of the included reviews/meta-analyses provided a full definition—and (2) short sleep duration appeared to be related to obesity and diabetes, whereas relations with cardiovascular disease (CVD), cognitive functioning, emotional problems, general health, and mortality, showed either small effects and appeared to be complex (e.g., for CVD and cognitive functioning), or studies were scarce or completely lacking (e.g., mortality in children/adolescents and emotional problems in adults).

Summary

Although short or insufficient sleep is highly prevalent and is associated with impaired mental and physical wellbeing, as well as pervasive negative consequences for daytime functioning, the concepts of “chronicity” and “chronic sleep reduction” have not been clearly defined and its effects on health are therefore still largely unknown. Moreover, there are large research gaps concerning studies on the relations between short sleep and health consequences. Further studies are recommended to define and operationalize chronicity of sleep reduction and develop measurements that adequately represent the complexity of the concept.

Perceived daily sleep need and sleep debt in adolescents: associations with daily affect over school and vacation periods

STUDY OBJECTIVES

To describe trajectories of perceived daily sleep need and sleep debt, and examine if cumulative perceived sleep debt predicts next-day affect.

METHODS

Daily sleep and affect were measured over 2 school weeks and 2 vacation weeks (N=205, 54.1% females, M±SDage = 16.9±0.87 years). Each day, participants wore actigraphs and self-reported the amount of sleep needed to function well the next day (i.e., perceived sleep need), sleep duration, and high- and low-arousal positive and negative affect (PA, NA). Cumulative perceived sleep debt was calculated as the weighted average of the difference between perceived sleep need and sleep duration over the past 3 days. Cross-lagged, multilevel models were used to test cumulative sleep debt as a predictor of next-day affect. Lagged affect, day of the week, study day, and sociodemographics were controlled.

RESULTS

Perceived sleep need was lower early in the school week, before increasing in the second half of the week. Adolescents accumulated perceived sleep debt across school days and reduced it during weekends. On weekends and vacations, adolescents self-reported meeting their sleep need, sleeping the amount, or more than the amount of sleep they perceived as needing. Higher cumulative actigraphy sleep debt predicted higher next-day high arousal NA; higher cumulative diary sleep debt predicted higher NA (regardless of arousal), and lower low arousal PA the following day.

CONCLUSION

Adolescents experienced sustained, cumulative perceived sleep debt across school days. Weekends and vacations appeared to be opportunities for reducing sleep debt. Trajectories of sleep debt during vacation suggested recovery from school-related sleep restriction. Cumulative sleep debt was related to affect on a daily basis, highlighting the value of this measure for future research and interventions.

Greater adolescent tiredness is related to more emotional arousal during a hyperventilation task: An area under the curve approach

INTRODUCTION

Approximately 36% of adolescents report sleep problems (Crowley et al., 2018). Understanding the relation between sleep and emotional experience is crucial in understanding the high incidence of mental health concerns during adolescence. The current study sought to expand understanding in the area by testing the hypothesis that baseline tiredness ratings would predict greater emotional arousal and negative valence across the course of emotional response elicited by a voluntary hyperventilation procedure.

METHODS

A community sample of 110 youth (10-18 years; 47.8% girls) provided baseline tiredness ratings and ratings of emotional valence and arousal, 2 min before, immediately after, and 3 min after a hyperventilation task. The area under the curve (AUC) was calculated using the repeated measures of valence and arousal, and correlations between the response curves and baseline tiredness were examined.

RESULTS AND CONCLUSIONS

Findings indicated baseline tiredness was positively associated with AUC arousal (r = 0.23), but not valence. This suggests daytime tiredness is associated with the degree of emotional arousal elicited by a psychobiological stressor. By extension, adolescents may experience more arousing emotional reactions when tired, and thus the common sleep deprivation observed during this developmental period may increase risk for mental health problems associated with elevated emotional reactivity.

Sleep duration and mood in adolescents: an experimental study

STUDY OBJECTIVES

This study examines the relationship between experimentally manipulated sleep duration and mood in adolescents.

METHODS

Thirty-four adolescents (20 male), aged 15-17 years, lived in a sleep laboratory for 10 days and 9 nights. They were allocated to one of three sleep "doses" for five consecutive nights for 5, 7.5, or 10 h sleep opportunity per night. Two baseline nights and two recovery nights entailed 10 h sleep opportunity per night. Mood was measured every 3 h during wake using unipolar visual analogue scales measuring the mood states "depressed," "afraid," "angry," "confused," "anxious," "happy," and "energetic."

RESULTS

Mixed models analyses with post hoc comparisons revealed that participants in the 5-h group, but not the 7.5- or 10-h groups, reported being significantly more depressed, angry, and confused during sleep restriction than at baseline. Adolescents were significantly less happy and energetic during sleep restricted to 5 h and significantly less energetic during sleep restricted to 7.5 h. When adolescents had 10 h sleep opportunities their happiness significantly increased. No statistically significant effects of sleep restriction were found for fear or anxiety, although small-to-moderate effects of sleep restricted to 5 or 7.5 h were found. Two nights of recovery sleep was not sufficient to recover from increased negative mood states for the 5-h group, although recovery occurred for positive mood states.

CONCLUSIONS

Given the prevalence of insufficient sleep and the rising incidence of mood disorders and dysregulation in adolescents, these findings highlight the importance of sufficient sleep to mitigate these risks.

Homeostatic Response to Sleep Restriction in Adolescents

The high prevalence of chronic sleep restriction in adolescents underscores the importance of understanding how adolescent sleep is regulated under such conditions. One component of sleep regulation is a homeostatic process: if sleep is restricted, then sleep intensity increases. Our knowledge of this process is primarily informed by total sleep deprivation studies and has been incorporated in mathematical models of human sleep regulation. Several animal studies, however, suggest that adaptation occurs in chronic sleep restriction conditions, showing an attenuated or even decreased homeostatic response. We investigated the homeostatic response of adolescents to different sleep opportunities. Thirty-four participants were allocated to one of three groups with 5, 7.5 or 10 h of sleep opportunity per night for 5 nights. Each group underwent a protocol of 9 nights designed to mimic a school week between 2 weekends: 2 baseline nights (10 h sleep opportunity), 5 condition nights (5, 7.5 or 10 h), and two recovery nights (10 h). Measures of sleep homeostasis (slow-wave activity and slow-wave energy) were calculated from frontal and central EEG derivations and compared to predictions derived from simulations of the homeostatic process of the two-process model of sleep regulation. Only minor differences were found between empirical data and model predictions, indicating that sleep homeostasis is preserved under chronic sleep restriction in adolescents. These findings improve our understanding of effects of repetitive short sleep in adolescents.

Circadian typology and implications for adolescent sleep health. Results from a large, cross-sectional, school-based study

STUDY OBJECTIVES

To investigate circadian typology in a large, representative sample of Norwegian adolescents, and its implications for sleep health.

METHODS

The sample included 3920 1^st year high school students aged 16-17 years. Respondents completed a web-based survey, including the short version of the Horne-Ostberg Morningness-Eveningness Questionnaire (rMEQ), the Munich Chronotype Questionnaire (MCTQ) and items on sleep-related behaviors (eg electronic media usage in bed, consumption of caffeinated beverages), sleep beliefs and daytime sleepiness. Data were analyzed using one-way ANOVAs and Chi-squared tests.

RESULTS

In all, 7.8% were categorized as morning, 52.3% as intermediate and 39.9% as evening types, respectively. Evening types had later sleep timing, longer sleep latency, more social jetlag and shorter school day sleep duration than morning types, with intermediate types displaying a sleep pattern between these two extremes. None of the circadian types met the minimum recommended amount of sleep on school nights (ie 8+ hours), and only morning types had a mean sleep duration of 7+ hours (7:19 h, nearly 1 h more than evening types who slept 6:20 h, p < 0.001). Evening types reported more use of electronic media in bed, more consumption of caffeinated beverages and more daytime sleepiness than the other circadian types. They were also less satisfied with their school day sleep duration and perceived it more difficult to change their sleep pattern.

CONCLUSIONS

Results from this study suggest that eveningness represents a sleep health challenge for older adolescents.

COVID-19 and sleep patterns in adolescents and young adults

OBJECTIVE

In March 2020, the world experienced a global pandemic, which involved the shutdown of schools or a transposition to remote teaching in most countries. The objective of the present study was to investigate the impact of the COVID-19 pandemic related lockdown on sleep patterns and sleep quality in adolescents and young adults.

METHODS

An online survey was conducted in June 2020 with adolescents and young adults (n = 498) aged 12-25 years. Participants had to answer questions on sleep, first retrospectively, referring to the time prior to the pandemic, and then referring to the time during the pandemic.

RESULTS

A pronounced shift towards later sleep combined with an increase in sleep duration was found during the pandemic. However, these changes in sleep habits were more pronounced in adolescents than in young adults and seem to occur mostly during weekdays compared to weekends. During the pandemic, teens also reported an improvement in daytime sleepiness and subjective sleep quality, while young adults reported an increase in sleep difficulties associated with sleep onset difficulties, nocturnal and early morning awakenings, and nightmares.

CONCLUSIONS

The COVID-19 related lockdown seems to have had a beneficial effect on sleep in adolescents. In young adults, benefits are not as obvious. These results support that later school start times would be beneficial for adolescents. However, in young adults it could be important to investigate the effects of other situational or interindividual factors (stress, lifestyle habits, employment, etc.).

Experimentally imposed circadian misalignment alters the neural response to monetary rewards and response inhibition in healthy adolescents

BACKGROUND

Sleep and circadian timing shifts later during adolescence, conflicting with early school start times, and resulting in circadian misalignment. Although circadian misalignment has been linked to depression, substance use, and altered reward function, a paucity of experimental studies precludes the determination of causality. Here we tested, for the first time, whether experimentally-imposed circadian misalignment alters the neural response to monetary reward and/or response inhibition.

METHODS

Healthy adolescents (n = 25, ages 13-17) completed two in-lab sleep schedules in counterbalanced order: An 'aligned' condition based on typical summer sleep-wake times (0000-0930) and a 'misaligned' condition mimicking earlier school year sleep-wake times (2000-0530). Participants completed morning and afternoon functional magnetic resonance imaging scans during each condition, including monetary reward (morning only) and response inhibition (morning and afternoon) tasks. Total sleep time and circadian phase were assessed via actigraphy and salivary melatonin, respectively.

RESULTS

Bilateral ventral striatal (VS) activation during reward outcome was lower during the Misaligned condition after accounting for the prior night's total sleep time. Bilateral VS activation during reward anticipation was lower during the Misaligned condition, including after accounting for covariates, but did not survive correction for multiple comparisons. Right inferior frontal gyrus activation during response inhibition was lower during the Misaligned condition, before and after accounting for total sleep time and vigilant attention, but only during the morning scan.

CONCLUSIONS

Our findings provide novel experimental evidence that circadian misalignment analogous to that resulting from school schedules may have measurable impacts on healthy adolescents' reward processing and inhibition of prepotent responses.

Daily light exposure, sleep-wake cycle and attention in adolescents from different urban contexts

OBJECTIVE

to compare daily light exposure, activity-rest rhythm, sleep-wake cycle (SWC) and attention in Brazilian students living in different levels of urbanization.

METHODS

115 adolescents (74 girls), aged 14-18 years (mean 15.5 ± 0.7 years), from the first years of high school have participated. The SWC was evaluated by actimetry and a Sleep Diary for 10 days. Besides, the "Health and Sleep" Questionnaire, the Morningness and Eveningness Scale for adolescents, the Pittsburgh Sleep Quality Index, and the Pediatric Daytime Sleepiness Scale were answered. Attention was assessed by a Continuous Performance Task.

RESULTS

In the less urbanized region, there were a greater exposure to light during the day accompanied by a higher proportion of morning-types and less occurrence of excessive daytime sleepiness. Otherwise, in the more urbanized region, adolescents showed a trend to sleep less in weekdays and presented more irregularity in sleep duration between weekdays and weekend, with 83 ± 15% of sleep efficiency, 01:04 ± 1:30 h of WASO and 7 ± 6.7 awakenings per night on the weekdays, suggestive of poor sleep quality. Despite of this, they showed better attentional performance: more correct responses (tonic and phasic alertness, and sustained attention) and less omissions (for all components). Regardless of the degree of urbanization, there was partial sleep deprivation, irregular sleep schedules and poor sleep quality in adolescents.

CONCLUSIONS

The daily light exposure and activity-rest profiles, SWC and attention in adolescents varied according to the degree of urbanization. Besides, the negative impacts of early school starting times leading to sleep deprivation, irregular sleep times and poor sleep quality were observed irrespective of the degree of urbanization, reinforcing that the early school starting time at morning is a strong temporal challenge for teenagers, having negative impacts on cognition and academic performance.

Nodding off but can't disconnect: development and validation of the iNOD index of Nighttime Offline Distress

BACKGROUND

There is a pressing need to update sleep models, education and treatment to better reflect the realities of sleep in a 24/7 connected social world. Progress has been limited to date by available measurement tools, which have largely focused on the frequency or duration of individuals' social media use, without capturing crucial sleep-relevant aspects of this inherently social and interactive experience.

METHODS

Survey data from 3008 adolescents (aged 10-18 years) was used to rigorously develop and validate a new self-report measure that quantifies difficulty disengaging from social media interactions at night: the index of Nighttime Offline Distress (iNOD). Exploratory and Confirmatory Factor analyses in a random split sample produced a ten-item two-factor solution, with subscales capturing concerns about Staying Connected and Following Etiquette (Cronbach's alphas = 0.91 and 0.92 respectively).

RESULTS

Those with higher scores on these subscales tended to report using social media for longer after they felt they should be asleep (r_s = 0.41 and 0.26, respectively), shorter sleep duration (r_s = -0.24 and -0.17, respectively) and poorer sleep quality (r_s = -0.33 and -0.31, respectively). Results also pointed towards a potentially fragmented process of sleep displacement for those who may struggle to disconnect - and to stay disconnected - from social interactions in order to allow sufficient uninterrupted sleep opportunity.

CONCLUSIONS

These findings can inform current models for understanding normal and disordered sleep during adolescence, whilst highlighting specific social concerns as important potential targets for sleep education efforts.

A Model of Adolescent Sleep Health and Risk for Type 2 Diabetes

PURPOSE OF REVIEW

This paper presents a review of the current literature in support of a model explaining the relationships between sleep health and risk for type 2 diabetes in adolescents.

RECENT FINDINGS

Short sleep duration is associated with risk of developing obesity in youth. Sleep restriction increases energy expenditure, but also increases hunger, appetite, and food intake, causing positive energy balance, impacting appetite-regulating hormones, and leading to increased eating late at night. Insufficient sleep may lead to reduced physical activity and greater sedentary behaviors. In addition, short sleep duration is associated with reduced insulin sensitivity. The cumulative negative consequences of insufficient sleep increase risk for type 2 diabetes. Applications to clinical care, public policy, and future research are discussed. Insufficient sleep in adolescence increases risk for type 2 diabetes directly through impact on insulin sensitivity and indirectly through increased dietary intake, sedentary activity, and weight gain.

Influence of life habits and behaviors on the health of adolescents

Objective: To identify the influence of life habits and behaviors on the health of adolescents. Materials and method: This is a quantitative research, with an exploratory and descriptive approach, developed with 124 adolescents, students from a pre-professional school in southernmost Brazil. Data was collected by means of a questionnaire. The analysis was performed using descriptive statistics by means of the SPSS software, version 20.0. Results: The high consumption of ultra-processed food in intermediate meals and insufficient sleep hours per night cause risks to the health of adolescents. Practicing physical activities has proved to be a health protection habit. Conclusions: The adolescents need to reframe the importance of healthy eating and sleep in their routine. It was observed that there are modifiable factors for sleep improvement in quality and quantity, as well as the value and inclusion of in natura food in intermediate meals. We believe that the role of nurses in school spaces, giving rise to joint reflections on the process of self-care, health concepts, risky and healthy behaviors, is capable of promoting and protecting the health of adolescents and preventing morbidities in the future.

Association between Self-Reported Sleep Duration and Dietary Nutrients in Korean Adolescents: A Population-Based Study

(1) Background: Adolescence is a transient period from childhood to adulthood, which is characterized by rapid physical growth and psychological changes, including sleep. Because the relationship between insufficient sleep and obesity has been observed in children and adults, the potential links between sleep, dietary intake, and nutrition have received increased attention. We aimed to examine the association of sleep duration with dietary nutrients intake in South Korean adolescents; (2) Methods: This population-based, cross-sectional study analyzed the data obtained from the Korea National Health and Nutrition Examination Survey between 2013 and 2015. Data related to 1422 adolescents aged 12–18 years (741 males and 681 females) were included in the analysis. Sleep duration was assessed using a self-reported questionnaire. Nutrient intake, including daily total energy intake, was assessed with a 24-h dietary recall questionnaire; (3) Results: Most males (84.4%) and females (86.4%) reported < 9 h of sleep per night. Short sleep duration was inversely associated with body mass index and obesity in both sexes. We found that higher intake of fiber and lower intake of sodium were associated with longer sleep duration (P < 0.05). When comparing the intake above and below the estimated average requirements (EAR), the difference in sleep duration was significant in the group that consumed vitamins B₁ and C below EAR; (4) Conclusions: The findings of this study indicate that sleep duration can be associated with intake of some nutrients, which may also be associated with obesity in adolescents. Therefore, it is possible to prevent obesity and its complications by controlling the sleep duration and intake of nutrients of adolescents.

Relationships between Extra-School Tutoring Time, Somatic Symptoms, and Sleep Duration of Adolescent Students: A Panel Analysis Using Data from the Korean Children and Youth Panel Survey

As private tutoring has expanded worldwide, it has been noted that private tutoring and associated emotional distress can affect sleep duration and the health of adolescent students. However, the relationships between extra-school tutoring time, somatic symptoms, defined as physical symptoms of emotional distress, and sleep duration in adolescents has rarely been determined. The aim of this study was to identify these relationships in adolescent students. Data from the Korean Children and Youth Panel Survey were analyzed to address the research questions. Weekday sleep duration, extra-school tutoring time, and somatic symptoms were measured using adolescents’ self-report questionnaires. A multilevel, structural equation model was utilized to test the relationships between these variables and was deemed appropriate considering the repeated measure of the panel data. After controlling for respondent sex, parent working status and education level, and family structure, adolescents’ extra-school tutoring time and level of somatic symptoms were associated with sleep duration during weekdays. Furthermore, the association between extra-school tutoring time and sleep duration was partially mediated by somatic symptoms. Korean adolescent students slept less than the recommended duration. Intervention programs that increase parental interest and attention in adolescent students’ lives, not only focused on academic achievement but also emotional distress is needed. Researchers and policymakers should understand recommended age-appropriate sleep duration and the educational culture and provide balanced strategies between the consideration of the effect of private education on academic achievement and the need to guarantee physical and mental health in adolescent students.

Association of Delaying School Start Time With Sleep Duration, Timing, and Quality Among Adolescents

IMPORTANCE

Sleep is a resource that has been associated with health and well-being; however, sleep insufficiency is common among adolescents.

OBJECTIVE

To examine how delaying school start time is associated with objectively assessed sleep duration, timing, and quality in a cohort of adolescents.

DESIGN, SETTING, AND PARTICIPANTS

This observational cohort study took advantage of district-initiated modifications in the starting times of 5 public high schools in the metropolitan area of Minneapolis and St Paul, Minnesota. A total of 455 students were followed up from grade 9 (May 3 to June 3, 2016) through grade 11 (March 15 to May 21, 2018). Data were analyzed from February 1 to July 24, 2019.

EXPOSURES

All 5 participating schools started early (7:30 am or 7:45 am) at baseline (2016). At follow-up 1 (2017) and continuing through follow-up 2 (2018), 2 schools delayed their start times by 50 and 65 minutes, whereas 3 comparison schools started at 7:30 am throughout the observation period.

MAIN OUTCOMES AND MEASURES

Wrist actigraphy was used to derive indices of sleep duration, timing, and quality. With a difference-in-difference design, linear mixed-effects models were used to estimate differences in changes in sleep time between delayed-start and comparison schools.

RESULTS

A total of 455 students were included in the analysis (among those identifying sex, 225 girls [49.5%] and 219 boys [48.1%]; mean [SD] age at baseline, 15.2 [0.3] years). Relative to the change observed in the comparison schools, students who attended delayed-start schools had an additional mean 41 (95% CI, 25-57) objectively measured minutes of night sleep at follow-up 1 and 43 (95% CI, 25-61) at follow-up 2. Delayed start times were not associated with falling asleep later on school nights at follow-ups, and students attending these schools had a mean difference-in-differences change in weekend night sleep of -24 (95% CI, -51 to 2) minutes from baseline to follow-up 1 and -34 (95% CI, -65 to -3) minutes from baseline to follow-up 2, relative to comparison school participants. Differences in differences for school night sleep onset, weekend sleep onset latency, sleep midpoints, sleep efficiency, and the sleep fragmentation index between the 2 conditions were minimal.

CONCLUSIONS AND RELEVANCE

This study found that delaying high school start times could extend adolescent school night sleep duration and lessen their need for catch-up sleep on weekends. These findings suggest that later start times could be a durable strategy for addressing population-wide adolescent sleep deficits.

The challenges of adolescent sleep

Sleep is vital for our physical, emotional and cognitive health. However, adolescents face many challenges where their sleep is concerned. This is reflected in their sleep patterns including the timing of their sleep and how much sleep they achieve on a regular basis: their sleep is characteristically delayed and short. Notably, insufficient sleep is associated with impairments in adolescent functioning. Endogenous and exogenous factors are known to affect sleep at this age. Alterations in the bioregulation of sleep, comprising the circadian timing system and the sleep/wake homeostatic system, represent the intrinsic mechanisms at work. Compounding this, environmental, psychosocial and lifestyle factors may contribute to shortened sleep. This review discusses the amount of sleep gained by adolescents and its implications, the challenges to adolescent sleep and the interventions introduced in an effort to prioritize sleep health in this important developmental period.

Later School Start Time: The Impact of Sleep on Academic Performance and Health in the Adolescent Population

The crucial role of sleep in physical and mental health is well known, especially during the developmental period. In recent years, there has been a growing interest in examining the relationship between sleep patterns and school performance in adolescents. At this stage of life, several environmental and biological factors may affect both circadian and homeostatic regulation of sleep. A large part of this population does not experience adequate sleep, leading to chronic sleep restriction and/or disrupted sleep–wake cycles. Studies investigating the effects of different sleep–wake schedules on academic achievement showed that impaired sleep quality and quantity are associated with decreased learning ability and compromised daytime functioning. This review focuses on the most recent studies that evaluated the effects of modified school start time on sleep patterns and related outcomes. Moreover, based on the available empirical evidence, we intend to propose a direction for future studies targeted to implement prevention or treatment programs by modifying sleep timing.

Circadian Phase Advances in Response to Weekend Morning Light in Adolescents With Short Sleep and Late Bedtimes on School Nights

Many adolescents fall asleep too late to get enough sleep (8-10 h) on school nights. Morning bright light advances circadian rhythms and could help adolescents fall asleep earlier. Morning bright light treatment before school, however, is difficult to fit into their morning schedule; weekends are more feasible. We examined phase advances in response to morning light treatment delivered over one weekend. Thirty-seven adolescents (16 males; 14.7-18.0 years) who reported short school-night sleep (≤7 h) and late bedtimes (school-nights ≥23:00; weekend/non-school nights ≥24:00) slept as usual at home for ∼2 weeks ("baseline") and then kept a fixed sleep schedule (baseline school-night bed and wake-up times ±30 min) for ∼1 week before living in the lab for one weekend. Sleep behavior was measured with wrist actigraphy and sleep diary. On Saturday morning, we woke each participant 1 h after his/her midpoint of baseline weekend/non-school night sleep and 1 h earlier on Sunday. They remained in dim room light (∼20 lux) or received 1.5 or 2.5 h of intermittent morning bright light (∼6000 lux) on both mornings. The dim light melatonin onset (DLMO), a phase marker of the circadian timing system, was measured on Friday and Sunday evenings to compute the weekend circadian phase shift. The dim room light and 1.5-h bright light groups advanced the same amount (0.6 ± 0.4 and 0.6 ± 0.5 h). The 2.5-h bright light group advanced 1.0 ± 0.4 h, which was significantly more than the other groups. These data suggest that it is possible to phase advance the circadian clock of adolescents who have late bedtimes and short school-night sleep in one weekend using light that begins shortly after their sleep midpoint.

Association between depressive symptoms and sleep neurophysiology in early adolescence

BACKGROUND

Depression is highly prevalent among adolescents, and depressive symptoms rise rapidly during early adolescence. Depression is often accompanied by subjective sleep complaints and alterations in sleep neurophysiology. In this study, we examine whether depressive symptoms, measured on a continuum, are associated with subjective and objective (sleep architecture and neurophysiology) measures of sleep in early adolescence.

METHODS

High-density sleep EEG, actigraphy, and self-reported sleep were measured in 52 early adolescents (12.31 years; SD: 1.121; 25 female). Depressive symptoms were measured on a continuum using the Center for Epidemiological Studies Depression Scale (CES-D). The association between depressive symptoms and 2 weeks of actigraphy, self-reported sleep, sleep architecture, and sleep neurophysiology (slow wave activity and sigma power) was determined via multiple linear regression with factors age, sex, and pubertal status.

RESULTS

Despite no association between polysomnography measures of sleep quality and depressive symptoms, individuals with more depressive symptoms manifested worse actigraphically measured sleep. Less sleep spindle activity, as reflected in nonrapid eye movement sleep sigma power, was associated with more depressive symptoms over a large cluster encompassing temporal, parietal, and occipital regions. Furthermore, worse subjectively reported sleep quality was also associated with less sigma power over these same areas. Puberty, age, and sex did not impact this association.

CONCLUSIONS

Sleep spindles have been hypothesized to protect sleep against environmental disturbances. Thus, diminished spindle power may be a subtle sign of disrupted sleep and its association with depressive symptoms in early adolescence may signal vulnerability for depression.