Relationships between school start time, sleep duration, and adolescent behaviors

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.

Effects of school start time and its interaction with the solar clock on adolescents' chronotype and sleep: A systematic review and meta-analysis

Adolescents' late chronotypes colliding with early school start times (SSTs) are associated with students' unhealthy sleep habits. Most studies comparing different SSTs associate later SSTs with longer sleep duration and lower social jetlag. However, the magnitude of the effect varies between studies and the effect of different SSTs on chronotype is not well established. Importantly, although human circadian rhythms are entrained by sunlight, when studying the effect of different SSTs on adolescents' sleep habits usually only the social clock, and not the solar clock, is considered. This meta-analysis investigates whether later SSTs affect adolescents' sleep habits and chronotype and it assesses factors that can modulate this effect, including the relative importance of social and solar clocks. Here, through a database search we identify 37 studies comparing the effect of different SSTs on adolescents' sleep habits and/or chronotype. Random effect meta-analyses showed that later SSTs are associated with later sleep timings and longer sleep duration on weekdays, lower levels of social jetlag, and later chronotypes. Several meta-regressions reveal that the distance between compared SSTs and the interplay between SSTs and the solar clock modulate the effect of different SSTs on sleep timings and duration on weekdays.

Shorter sleep among adolescents is associated with lower fruit and vegetable consumption the following day

BACKGROUND

Insufficient sleep has been associated with weight gain and metabolic dysregulation, with one suggested mechanism being through reduction in diet quality. Experimental evidence supports a causal effect of sleep timings on diet but this may not be applicable to a free-living adolescent population. In this analysis we use daily measures of sleep timings and diet quality, to examine the effect of sleep duration and timing on diet quality the following day among free-living adolescents.

METHODS

The ROOTS study is a prospective cohort recruited from secondary schools in Cambridgeshire and Suffolk (UK). Participants (n = 815) at mean age 15.0y (SD 0.3y) completed a diet diary and wore a combined heart rate and accelerometer device over 4 consecutive days. Sleep duration and timing (midpoint) were derived from acceleration and heart rate traces, while daily energy density and fruit and vegetable intake were calculated from dietary data. Analyses were performed at day-level (1815 person-days). Multilevel random effects models were used to test associations between sleep each night and subsequent day diet, with daily sleep and diet measures nested within individuals and schools, and adjusted for day-level and individual-level confounding variables.

RESULTS

Adolescents slept a mean of 7.88 hrs (SD 1.10) per night, reporting a mean energy density of 2.12 kcal/g (SD 0.48) and median energy-adjusted daily fruit and vegetable intake of 137.3 g (IQR 130.4). One hour shorter sleep duration was associated with lower intake of fruit and vegetables (-6.42 g, 95%CI -1.84, -10.99) the following day. An association with higher dietary energy density (0.016 kcal/g, 95%CI 0.034, -0.002) the following day was observed but did not reach statistical significance. Sleep timing was not associated with either fruit and vegetable intake (-2.52 g/d, 95%CI -7.66, 2.62) or dietary energy density (-0.001 kcal/g, 95%CI -0.022, 0.020).

CONCLUSIONS

Our observational findings from a free-living adolescent population support the experimental evidence for a causal role of sleep on diet, with shorter sleep duration at night leading to a small decrease in diet quality the following day. These findings support experimental evidence to suggest inclusion of sleep duration as one component of interventions designed to improve diet quality and weight status in adolescents.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Device-measured sleep onset and duration in the development of depressive symptoms in adolescence

BACKGROUND

Sleep deprivation in adolescence is increasing in prevalence and may be linked to subsequent depression. Findings regarding associations between sleep duration, sleep onset time, and the development of depressive symptoms over time in adolescents are mixed, and rely on subjective measures of sleep.

METHODS

Sleep onset and duration were assessed using a combined heart rate monitor and accelerometer and self-report in 688 participants from the ROOTS study at age 15. Participants reported depressive symptoms at ages 14.5, 16, and 17.5, using the Mood and Feelings Questionnaire. Latent growth curve modelling was used to model development of depressive symptoms and test associations with baseline sleep onset and duration.

RESULTS

Cross-sectionally, falling asleep later and shorter sleep duration were both associated with higher depressive symptoms in males and females, using both device-measured and self-reported sleep. There were no longitudinal associations between baseline sleep duration and change in depressive symptoms. A later sleep onset-time was associated with a decrease in depressive symptoms over time, in females only, using device-measured sleep only.

LIMITATIONS

The current sample was more economically advantaged and ethnically white than the UK average, and with lower MFQ symptoms than the original cohort, which may reduce generalisability.

CONCLUSIONS

Adolescents who fall asleep later or sleep less have higher levels of depressive symptoms cross-sectionally, but do not show increases in depressive symptoms over time. Interventions targeting sleep onset and duration in adolescence may improve mental health in the short-term but the possibility of reverse causality should be explored further.

Neuroscience Knowledge and Endorsement of Neuromyths among Educators: What Is the Scenario in Brazil?

The field of neuroscience has seen significant growth and interest in recent decades. While neuroscience knowledge can benefit laypeople as well as professionals in many different areas, it may be particularly relevant for educators. With the right information, educators can apply neuroscience-based teaching strategies as well as protect themselves and their students against pseudoscientific ideas and products based on them. Despite rapidly growing sources of available information and courses, studies show that educators in many countries have poor knowledge of brain science and tend to endorse education-related neuromyths. Poor English skills and fewer resources (personal, institutional and governmental) may be additional limitations in Latin America. In order to better understand the scenario in Latin America’s largest country, we created an anonymous online survey which was answered by 1634 individuals working in education from all five regions of Brazil. Respondents stated whether they agreed with each statement and reported their level of confidence for each answer. Significant differences in performance were observed across regions, between educators living in capital cities versus the outskirts, between those teaching in private versus public schools, and among educators teaching different levels (pre-school up to college/university). We also observed high endorsement of some key neuromyths, even among groups who performed better overall. To the best of our knowledge, this is the first study to conduct a detailed analysis of the profile of a large group of educators in Brazil. We discuss our findings in terms of efforts to better understand regional and global limitations and develop methods of addressing these most efficiently.

Sleep Deficiency in Adolescents: The School Start Time Debate

Adolescence is commonly accepted as a challenging time for sleep, with multiple factors contributing to sleep deficiency in adolescents. These include physiologic changes with shifts in their circadian rhythm; medical sleep disorders; and social, cultural, and environmental factors. Early school start times negatively affect sleep in adolescents as well, with poorer outcomes in their overall health, wellbeing, and performance. This article highlights the different contributing factors for sleep deficiency in adolescents and the consequences of sleep deficiency. In addition, the authors discuss the impact of delayed school start times in improving adolescents' sleep and overall function.

A Review on Measures to Rejuvenate Immune System: Natural Mode of Protection Against Coronavirus Infection

SARS-CoV-2, a novel Corona virus strain, was first detected in Wuhan, China, in December 2019. As of December 16, 2021, almost 4,822,472 people had died and over 236,132,082 were infected with this lethal viral infection. It is believed that the human immune system is thought to play a critical role in the initial phase of infection when the viruses invade the host cells. Although some effective vaccines have already been on the market, researchers and many bio-pharmaceuticals are still working hard to develop a fully functional vaccine or more effective therapeutic agent against the COVID-19. Other efforts, in addition to functional vaccines, can help strengthen the immune system to defeat the corona virus infection. Herein, we have reviewed some of those proven measures, following which a more efficient immune system can be better prepared to fight viral infection. Among these, dietary supplements like- fresh vegetables and fruits offer a plentiful of vitamins and antioxidants, enabling to build of a healthy immune system. While the pharmacologically active components of medicinal plants directly aid in fighting against viral infection, supplementary supplements combined with a healthy diet will assist to regulate the immune system and will prevent viral infection. In addition, some personal habits, like- regular physical exercise, intermittent fasting, and adequate sleep, had also been proven to aid the immune system in becoming an efficient one. Maintaining each of these will strengthen the immune system, allowing innate immunity to become a more defensive and active antagonistic mechanism against corona-virus infection. However, because dietary treatments take longer to produce beneficial effects in adaptive maturation, personalized nutrition cannot be expected to have an immediate impact on the global outbreak.

Equal Benefits? An Examination of the Potential Consequences of Later School Start Times for Adolescents and Their Mental Health

BACKGROUND

Given the documented benefits of later school start times on adolescents' mental health, the aim of the current study was to examine if the association between school start times and depressive symptoms differed across adolescents from families of different socioeconomic status levels.

METHODS

Using a cross-sectional design, the current study incorporated an online survey for high school students and their parents across the United States, with average sleep duration measured through a 7-day sleep diary. A total of 193 adolescent (Mean_age  = 15.7 years old, SD = .94; 54.4% female; 71% white) and parent (Mean_age  = 47.6 years old, SD = 5.4; 80% female; 79% white) dyads participated. Adolescents reported on depressive symptoms, sleep quality and duration, chronotype, and demographic covariates; parents reported on school start times and socioeconomic status.

RESULTS

Results suggested that only in adolescents from higher socioeconomic status families (+1 SD) did the association between later start times and fewer depressive symptoms emerge as significant.

CONCLUSIONS

Although more school start times research is needed to understand its impact across diverse groups of students, current findings suggest a disproportionate benefit of reduced depression for youth from families of higher socioeconomic status with having a later start time.

Sleep improvements on days with later school starts persist after 1 year in a flexible start system

Early school times fundamentally clash with the late sleep of teenagers. This mismatch results in chronic sleep deprivation posing acute and long-term health risks and impairing students' learning. Despite immediate short-term benefits for sleep, the long-term effects of later starts remain unresolved. In a pre-post design over 1 year, we studied a unique flexible school start system, in which 10–12th grade students chose daily between an 8:00 or 8:50AM-start. Missed study time (8:00–8:50) was compensated for during gap periods or after classes. Based on 2 waves (6–9 weeks of sleep diary each), we found that students maintained their ~ 1-h-sleep gain on later days, longitudinally (n = 28) and cross-sectionally (n = 79). This gain was independent of chronotype and frequency of later starts but attenuated for boys after 1 year. Students showed persistently better sleep quality and reduced alarm-driven waking and reported psychological benefits (n = 93) like improved motivation, concentration, and study quality on later days. Nonetheless, students chose later starts only infrequently (median 2 days/week), precluding detectable sleep extensions in the flexible system overall. Reasons for not choosing late starts were the need to make up lost study time, preference for extra study time and transport issues. Whether flexible systems constitute an appealing alternative to fixed delays given possible circadian and psychological advantages warrants further investigation.

Impact of Reduced School Exposure on Adolescent Health Behaviors and Food Security: Evidence From 4-Day School Weeks

BACKGROUND

Four-day school week (FDSW) use has increased substantially among US districts in recent years, but limited data exist on health impacts of this school schedule. This study examined associations of reduced school exposure via FDSWs with adolescent health and risk behaviors, obesity, and food security.

METHODS

Self-report data from 8th- and 11th-grade students from the Oregon Healthy Teens survey across 5 survey years (odd years 2007-2015, total N = 91,860-104,108 respondents depending on the survey question) were linked to a FDSW indicator. Regression analyses controlling for student and school characteristics compared outcomes between students in 4- and 5-day schools overall (without school fixed effects) and outcomes associated with switching to a FDSW (with school fixed effects).

RESULTS

When controlling for multiple student- and school-level factors, we observed adolescents in FDSW schools report they consume sugar sweetened beverages more frequently and water less frequently, have access to fewer days of physical education, are more likely to be food insecure, and are more likely to report the use of any drugs and specifically marijuana than 5-day school week students.

CONCLUSIONS

Limiting exposure to the school environment via FDSWs may impact adolescent health behaviors, including diet, physical activity, and drug use.

Associations of school night sleep duration and circadian preference with middle school-aged student attendance, tardiness, and suspension

OBJECTIVES

Research has associated both school night sleep duration (SNSD) and circadian preference (CP) with middle school-aged students' attendance and tardiness, but the interaction between these characteristics remains unexplored within this context, along with the impact of SNSD and CP on school suspension likelihood. Thus, this study investigated associations between SNSD, CP, and their interaction with middle school-aged student attendance, tardiness, and suspension, while accounting for sociodemographic characteristics.

PARTICIPANTS

About 4175 students from 12 middle schools in the Madison, Wisconsin, Metropolitan School District.

METHODS

Students completed a computer-based, sleep-related survey during class. Students reporting SNSD between 4 and 12 hours were included in the final analytical sample (N = 3860; mean age ± standard deviation = 12.0 ± 0.86 years; range = 10-16 years). CP was characterized using the single-item self-morningness/eveningness question. Linear mixed-effects regression estimated associations of SNSD and CP with tardiness and attendance. Logistic mixed-effects regression assessed associations with school suspension. Fully adjusted multilevel models included sociodemographic covariates, nesting students within schools.

RESULTS

About 3860 student responses comprised the final sample, which had a SNSD of 8.15 ± 1.37 hours and general eveningness preference. Short-and-long SNSD associated with lower attendance and increased out-of-school suspension. Greater eveningness preference was negatively associated with attendance and tardiness. No SNSD and CP interactions emerged. Associations between sociodemographic characteristics and attendance, tardiness, and suspension were observed.

CONCLUSIONS

Results support need for efforts to improve middle school-aged student sleep health and account for eveningness preference. Research clarifying the interactive influence of sleep, circadian, and sociodemographic characteristics on attendance and achievement is warranted.

Adolescent sleep duration and timing during early COVID-19 school closures

Objectives

To investigate adolescent sleep parameters and predictors during COVID-19-related school closures.

Methods

Original data were analyzed from a cross-sectional online survey of 590 teens in grades 6-12 attending school remotely in 35 US states, in May/June 2020.

Results

Students reported waking up 2.1-2.9 hours later during school closures and averaged 7.9-8.7 hours of sleep and 8.6-9.5 hours in bed on school nights. Compared to middle schoolers, high school students had later bed and wake times, accompanied by spending less time in bed and less time sleeping. The delay in wake time after school closures was also longer for high school students than for middle schoolers. Students with later class start times went to bed later, but also woke up later, slept longer, and spent more time in bed. When comparing intraindividual sleep before and after school closures, later class start times resulted in greater delays in wake time and greater odds of increased sleep duration. In addition, parent-set bedtimes were associated with earlier bedtimes and longer sleep duration during school closures.

Conclusions

As a result of COVID-19-related school closures and remote instruction, more middle and high school students achieved recommended amounts of sleep, primarily by waking up later in the morning. This study supports previous evidence that morning start schedule affects adolescent sleep behaviors. The implications of this study extend beyond COVID-19 school closures; adolescent sleep health improves with later school start times and fewer scheduled morning activities.

The Relationship of School Start Times, Sleep Duration and Mental Health among a Representative Sample of High School Students in Colorado, 2019

This cross-sectional study utilized responses from 46,537 students enrolled in grades 9 through 12 in 166 high schools across the state of Colorado via the 2019 Healthy Kids Colorado Survey to: (1) quantify the association between high school start times and student sleep duration and (2) investigate the associations between school start times and student mental health. Descriptive and bivariate analyses were used to investigate associations between school start times and self-reported demographic, sleep, and mental health factors. Survey-weighted multivariate regression modeling was used to investigate associations between school start times, sleep duration, and mental health. Schools with late start times (≥8:30 a.m.) saw 32.2% (95% Confidence Interval: 29.5-35.0) of students sleeping 8 h or more relative to 23.2% (22.0-24.4) in schools with very early start times (<8:00 a.m.). For every 15 min later school start time, students' sleep duration was 4.6 (3.4-5.9) min longer. Students attending schools with very early start times had 1.10 (0.95-1.27) times the odds of attempting suicide compared to those attending schools with later start times, while students at schools with early starts (8:00-8:29 a.m.) were associated with 1.11 (0.98-1.27) times the odds. Schools with later school start times had a statistically significantly higher proportion of students sleeping 8+ hours. Schools with start times before 8:30 a.m. had 10-11% higher odds of students attempting suicide compared to schools with late start times, though these differences were not statistically significant. Student mental health should continue to be investigated when assessing the potential impacts of delayed school start times.

Quality over quantity? Using sibling comparisons to examine relations between sleep quality, sleep duration, and delinquency

RATIONALE

A growing body of research suggests that adolescents with problematic sleep patterns are more likely to engage in externalizing and delinquent behaviors. Few studies, however, have examined the role of between- and within-family effects on this association to establish whether poor sleep is related to delinquency after controlling for familial confounding.

OBJECTIVE

The current study examines the relationship between self-reported restless sleep, sleep duration, and delinquency from ages 16-19 in a population-based sample of U.S. youth.

METHODS

Data from full siblings from the Children and Young Adult sample of the National Longitudinal Survey of Youth (1979) (CNLSY) are analyzed. Negative binomial regression models and sibling comparisons are estimated to assess between- and within-family effects of sleep on delinquency during ages 16-17. Sibling comparison cross-lagged models are then fitted to the data to examine whether sibling differences in sleep are related to sibling differences in changes in delinquency from ages 16-19.

RESULTS

Siblings with higher levels of self-reported restless sleep were more likely to report higher levels of delinquency at ages 16-17, net of observable covariates and unobservable familial confounders. Sibling differences in restless sleep at ages 16-17 were also associated with increases in delinquency at ages 18-19 after controlling for familial confounding and temporal stability in both sleep and delinquent behavior.

CONCLUSIONS

Findings suggest that perhaps sleep quality, rather than sleep duration, should be the primary target for intervention/prevention programming efforts for adolescent delinquency.

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.).

Evidence Base Update on Assessing Sleep in Youth

BACKGROUND

Sleep is vital to youth well-being and when it becomes disturbed - whether due to environmental or individual factors - mental and physical health suffer. Sleep problems can also be a symptom of underlying mental health disorders. Assessing different components of sleep, including quality and hygiene, can be useful both for identifying mental health problems and for measuring changes in well-being over time. However, there are dozens of sleep-related measures for youth and it can be difficult to determine which to select for a specific research or clinical purpose. The goal of this review was to identify sleep-related measures for clinical and/or research use in youth mental health settings, and to update the evidence base on this topic.

METHOD

We generated a list of candidate measures based on other reviews and searched in PubMed and PsycINFO using the terms "sleep" AND (measure OR assessment OR questionnaire) AND (psychometric OR reliability OR validity). Search results were limited to studies about children and adolescents (aged 2-17) published in English. Additional criteria for inclusion were that there had to be at least three publications reporting on the measure psychometrics in community or mental health populations. Sleep measures meeting these criteria were evaluated using the criteria set by De Los Reyes and Langer (2018).

RESULTS

Twenty-six measures, across four domains of sleep - insomnia, sleep hygiene, sleepiness, sleep quality - met inclusion criteria. Each measure had at least adequate clinical utility. No measure(s) emerged as superior across psychometric domains.

CONCLUSION

Clinicians and researchers must evaluate sleep measures for each use case, as the intended purpose will dictate which measure is best. Future research is necessary to evaluate measure performance in transdiagnostic mental health populations, including youth with serious mental illness.

Parental Expectations Are Associated with Children's Sleep Duration and Sleep Hygiene Habits

OBJECTIVE

Although parents recognize the importance of sleep, most have a limited understanding of children's sleep needs. This study examined whether parental expectations about sleep were linked to children and adolescent's sleep duration and sleep hygiene.

METHOD

Participants included 376 unique parent-child dyads. Parents (mean age = 47.0 years, SD = 6.7) estimated the number of hours of sleep their children (mean age = 13.0 years, SD = 2.2; 9-17 years) needed. These estimates were age-matched with recommended pediatric guidelines of the American Academy of Sleep Medicine and the National Sleep Foundation to yield 3 groups: expect less (8%-11%), expect appropriate (85%-89%), and expect more (3%-4%). Sleep duration for school nights and weekends were reported by children and parents. Sleep hygiene included sleep-promoting practices (quiet, dark bedroom, regular bed/wake times, consistent routine) and sleep-interfering practices (physiological arousal, presleep worry, alcohol/smoking intake, daytime napping, screen time).

RESULTS

Most parents (68.7%) endorsed that children do not get enough sleep. Linear and logistic regressions were used to assess the impact of parental expectations. For every additional hour of sleep expected, children slept between 15.5 (parent-report 95% confidence interval [CI], 9.0-22.0) and 17.9 minutes (child-report 95% CI, 9.7-26.2) longer on school nights, adjusted for age, sex, puberty, and parental education. For parents who expected less sleep than recommended, their children had the shortest sleep duration, least favorable sleeping environments, and greater presleep worry.

CONCLUSION

Parental sleep expectations were directly linked to children's sleep duration. Pediatricians and primary care providers can mobilize knowledge to optimally convey accurate information about developmental sleep needs and recommended hours to parents to promote longer sleep.

Weekly alternation of morning and afternoon school start times: implications for sleep and daytime functioning of adolescents

Study objectives

To examine sleep patterns of adolescents attending school on alternating morning schedule (MS) and afternoon schedule (AS) and to explore the contribution of sleep characteristics on the AS to prediction of adolescents’ daytime functioning.

Methods

The Croatian adaptation of the School Sleep Habits Survey for a two-shift school system was completed by 2,033 students (11–18 years old, 54 per cent females) whose school start times alternated weekly between 08:00 am and 14:00 pm.

Results

All age groups of adolescents reported delayed sleep when on the school week with an AS as compared with a MS. The average delay of bedtime was 36 minutes, and delay of wake-up time 121 minutes, which resulted in average sleep durations from 9.80 hours in 11-year olds to 8.39 hours in 18-year olds. Having more delayed wake-up times on the AS predicted more substance use and poorer grades. Having more delayed bedtimes not only predicted poorer grades but also predicted less depressed mood. Obtaining relatively longer sleep on AS predicted lower sleepiness, less depressed mood, and less frequent substance use.

Conclusions

The afternoon school start time enables sleep duration that is in line with adolescent sleep biology and contributes positively to daytime functioning. In many cases, a large delay in wake-up time is observed. At least part of that delay is not associated with adolescents’ circadian biology and contributes negatively to some indices of their daytime functioning. Further research of factors associated with extreme delays of sleep and/or interventions that could limit extreme sleep irregularity is required.

Correlates of short sleep duration among adolescents

INTRODUCTION

Short sleep duration is exceedingly common among adolescents and has implications for healthy youth development. We sought to document associations between adolescents' sleep duration and characteristics of their schedules, behaviors, and wellbeing.

METHODS

We used data from the baseline wave (9th grade year) of the START study, a cohort of 2134 students in five Minnesota high schools to assess how self-reported sleep duration was associated with the prevalence of time-use characteristics (i.e. activity schedules, screen use), sleep-wake problems (i.e. trouble waking in the morning, falling asleep in class, etc.), and risk of depression.

RESULTS

Shorter sleep duration was associated with various behaviors including greater computer/screen time and screen use after bed, a lower probability of doing homework, participation in sports doing chores on school nights, and reporting that it takes at least 20 min to fall asleep on school days (p < 0.05). Suboptimal sleep duration was also associated with a higher probability of all reported sleep-wake problems as well as higher risk of depressive symptoms (p < 0.05).

CONCLUSIONS

Given that getting an optimal amount of sleep can protect youth from risk and promote healthy youth development, it is critical that we gain a greater understanding of correlates and consequences of short sleep duration in order to develop a sleep-friendly culture for youth.

Relationships between sleep duration and adolescent depression: a conceptual replication

OBJECTIVE

Given the growing concern about research reproducibility, we conceptually replicated a previous analysis of the relationships between adolescent sleep and mental well-being using a new dataset.

METHODS

We conceptually reproduced an earlier analysis (Sleep Health, June 2017) using baseline data from the START Study. START is a longitudinal research study designed to evaluate a natural experiment in delaying high school start times, examining the impact of sleep duration on weight change in adolescents. In both START and the previous study, school day bedtime, wake-up time, and answers to a 6-item depression subscale were self-reported using a survey administered during the school day. Logistic regression models were used to compute the association and 95% confidence intervals between the sleep variables (sleep duration, wake-up time, and bedtime) and a range of outcomes.

RESULTS

In both analyses, greater sleep duration was associated with lower odds (P < .0001) of all 6 indicators of depressive mood. Five of the 6 sleep duration point estimates from the START Study and 4 of the 6 wake-up time point estimates fell within the 95% confidence intervals from the previous analysis. However, the associations between wake-up time and outcomes differed between the 2 studies' analyses.

CONCLUSION

Our findings add strength to the evidence supporting an association between short sleep duration and depression. This issue deserves attention from school districts given the current epidemic of short sleep duration among youth and the potential impact school scheduling can have on teen sleep.

Family contexts and sleep during adolescence

Sleep deprivation among adolescents has received much attention from health researchers and policymakers. Recent research indicates that variation in sleep duration from night to night is associated with multiple health outcomes. While there is evidence that sleep deprivation is socially patterned, we know little about how social contexts are associated with nightly sleep variation during adolescence (a life course stage when nightly sleep variation is particularly high). Given the importance of family environments for influencing adolescents’ sleep patterns, we hypothesized that disadvantaged family contexts would be associated with higher intra-individual variation (IIV) in nightly sleep duration, in addition to lower average nightly sleep duration. We tested these hypotheses in a diverse, population-based sample of 11–17 year-olds (N = 1095) from the Adolescent Health and Development in Context Study. Using survey and ecological momentary assessment data and a novel form of multi-level regression modeling (location-scale mixed modeling), we found that adolescents living in unmarried-parent, low SES, economically insecure, and high caregiver stress families had higher IIV in sleep than adolescents in families with more resources and less caregiver stress. There were fewer family effects on average sleep duration. This suggests family social and economic contexts are associated with an under-researched aspect of adolescent sleep, nightly variation, and may contribute to adolescent sleep problems with implications for their health and health disparities.

•

Consistency in nightly sleep duration is important for adolescent health.

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SES and family stress associated with variability in sleep duration in adolescents.

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Caregiver distress also associated with lower mean sleep duration among adolescents.

Insufficient sleep and suicidal ideation: a survey of 12,046 female adolescents

OBJECTIVES

Adolescence is a period of adaptation to social, hormonal, and physical changes. Because of these changes, adolescents are at risk for depression and suicidal thoughts. Female adolescents tend to be more sensitive to hormonal and emotional changes. Although the reciprocal relationship among depression, poor sleep quality, and suicide has been studied, whether decreased sleep time leads to depression-mediated suicide or induces suicide itself remains to be determined. Therefore, this study aimed to analyze (using a path analysis) the indirect (i.e., due to depression) and direct effects of sleep on suicidal ideation for female adolescents.

METHODS

We use nationally representative data from the Korean juvenile health behavior online survey to analyze the sleep effects on suicidal ideation. A total of 12,046 Korean female adolescents were included in this study. We analyzed data from the juvenile health behavior online survey (2017) conducted by the Korea Centers for Disease Control and Prevention and identified variables that could affect the mental health of female adolescents. A path analysis was performed to determine the direct role of sleep in suicidal ideation.

RESULTS

Decreased sleep was one of the several risk factors for suicidal ideation. Unexpectedly, after controlling for other risk factors including depression and socioeconomic factors, insufficient sleep was found to have direct effects on suicidal ideation. The indirect effect of insufficient sleep on suicidal ideation was mediated by depression.

CONCLUSION

Sleep is a modifiable factor that could reduce the suicide rate among female adolescents and could be targeted through public health prevention efforts.

SCHOOL START TIME AND PSYCHOLOGICAL HEALTH IN ADOLESCENTS

PURPOSE OF REVIEW

Later school start times are associated with a number of benefits for adolescents. The purpose of the current review is to summarize the literature regarding the effects of delaying school start times on adolescent psychological health.

RECENT FINDINGS

We identified eight observational studies that examined the relationship between schools' starting times and psychological outcomes. Of these, three were longitudinal studies that reported measures of adolescent mental health improved following a start time delay. Two cross-sectional studies showed that mental health scores were higher in schools with later compared to earlier start times. Three studies found no relationship between start time and mental health.

SUMMARY

In the majority of studies reviewed, later school start times were associated with greater adolescent psychological health. However, inherent design drawbacks in the studies prevent us from concluding that these associations are causal. There are a wide range of potential benefits, beyond mental health, that later high school start times offer. This encouraging, emergent literature on delayed start times has led many school districts to consider changes to their start times.

A process-oriented model linking adolescents' sleep hygiene and psychological functioning: the moderating role of school start times

OBJECTIVE

To examine a mediational model linking sleep hygiene to better mental health in adolescents via the mechanism of improved sleep quality, and to test the moderating role of school start times (SST) (before 8:30 AM vs. 8:30 AM or later) on that mediation model.

DESIGN

Cross-sectional.

SETTING

Online survey for high school students across the United States.

PARTICIPANTS

A total of 197 adolescents aged 14-17 years old (M_age = 15.6 years, SD = 1.8; 53% female) completed a baseline survey and 7-day sleep diaries; their parents (M_age = 47.7 years, SD = 5.5; 79% female) reported on family socioeconomic status and high SST.

MEASUREMENT

Adolescents reported on their sleep hygiene, circadian chronotype, daily levels of sleep quality and duration (morning diaries) and their depressive/anxiety symptoms (evening diaries) for 7 days.

RESULTS

A moderated-mediation model suggested that baseline sleep hygiene was directly associated with lower average daily depressive/anxiety symptoms across all students, but that association was marginally stronger in students with later SST (8:30 AM or later). A mediated path emerged only for students with earlier start times, suggesting that, for those students, baseline sleep hygiene was indirectly associated with lower average daily psychological symptoms by improving average daily sleep quality.

CONCLUSIONS

The current study is one of the first to demonstrate that SST might serve as a critical moderator in models of adolescent sleep and daily functioning. The findings provide additional evidence in the debate on how SST may affect adolescent health.