School Start Times Research Articles

Social Jetlag and Excessive Daytime Sleepiness from a Sample of Russian Children and Adolescents.

PurposeInsufficient nocturnal sleep is a primary source of excessive daytime sleepiness. Most previous research has focused on the disparity between sleep demands and study start times in adolescents. Fewer studies have focused on elementary schoolchildren. We hypothesize that late sleep timing is connected to excessive daytime sleepiness in a sample of Russian children and adolescents. The major goals of our study were to evaluate excessive daytime sleepiness in Russian schoolchildren and adolescents using the Russian version of the Pediatric Daytime Sleepiness Scale (PDSS) and to estimate its relationship with sleep-wake parameters using the Munich Chronotype Questionnaire (MCTQ).Materials and MethodsStudent subjects were from public educational facilities in the Republic of Karelia. They completed both the PDSS and the Munich Chronotype Questionnaire to estimate sleep parameters and chronotype (MSFsc). Five hundred and eleven students provided data for the PDSS and sleep-wake variables, and 479 for the full MCTQ data.ResultsThe overall prevalence of Excessive Daytime Sleepiness (EDS) in our sample was 18%. The total PDSS score was inversely correlated with sleep length on school nights and was independent of respondents’ sex. Higher PDSS scores were associated with later bedtimes on school days and free days, and shorter sleep duration on school days. Late chronotype and more pronounced social jetlag were both positively correlated with high PDSS scores. A negative correlation was found between chronotype and the duration of the sleep period on weekdays (p < 0.001) and a positive correlation was found on weekends (p < 0.001). Longer average sleep duration was positively related to less daytime sleepiness.ConclusionThis study suggests that excessive daytime sleepiness is chronotype-dependent. School start times could be shifted to a later hour to prolong sleep and reduce EDS.

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.

Sleep Health Promotion Interventions and Their Effectiveness: An Umbrella Review.

Sleep is receiving increasing attention in public health. The aim of this umbrella review is to determine what non-pharmacological sleep health interventions have been evaluated among healthy populations, by examining target groups, settings, and effectiveness in improving sleep quality and duration. Comprehensive searches were conducted in five electronic databases (January 1975–February 2019), yielding 6505 records. Thirty-five articles were selected meeting the following eligibility criteria: (1) systematic reviews or meta-analyses of (2) sleep health interventions in (3) primarily healthy populations. Two reviewers independently screened for inclusion, extracted the data, and assessed the review quality. This umbrella review was registered with PROSPERO (CRD42019126291). Eleven intervention types were defined, and their effectiveness discussed. Substantial evidence demonstrated the effectiveness of later school start times, behavior change methods, and mind–body exercise. Other intervention types, including sleep education or relaxation techniques, demonstrated some promising impacts on sleep, but with less consistent evidence. Results were limited by high heterogeneity between studies, mixed results, and variable review quality. Nevertheless, this umbrella review is a first step towards understanding the current state of sleep health promotion and gives an overview of interventions across the lifespan.

675 COVID-19 Instruction Style (In-Person, Virtual, Hybrid), School Start Times, and Sleep in a Large Nationwide Sample of Adolescents

IntroductionThe COVID-19 pandemic significantly disrupted how and when adolescents attended school. This analysis used data from the Nationwide Education and Sleep in TEens During COVID (NESTED) study to examine the association of instructional format (in-person, virtual, hybrid), school start times, and sleep in a large diverse sample of adolescents from across the U.S.MethodsIn October/November 2020, 5346 nationally representative students (grades 6–12, 49.8% female, 30.6% non-White) completed online surveys. For each weekday, participants identified if they attended school in person (IP), online-scheduled synchronous classes (O/S), online-no scheduled classes (asynchronous, O/A), or no school. Students reported school start times for IP or O/S days, and bedtimes (BT) and wake times (WT) for each applicable school type and weekends/no school days (WE). Sleep opportunity (SlpOpp, total sleep time proxy) was calculated from BT and WT. Night-to-night sleep variability was calculated with mean square successive differences.ResultsSignificant differences for teens’ sleep across instructional formats were found for all three sleep variables. With scheduled instructional formats (IP and O/S), students reported earlier BT (IP=10:54pm, O/S=11:24pm, O/A=11:36pm, WE=12:30am), earlier WT (IP=6:18am, O/S=7:36am, O/A=8:48am, WE=9:36am), and shorter SlpOpp (IP=7.4h, O/S=8.2h, O/A=9.2h, WE=9.2h). Small differences in BT, but large differences in WT were found, based on school start times, with significantly later wake times associated with later start times. Students also reported later WT on O/S days vs. IP days, even with the same start times. Overall, more students reported obtaining sufficient SlpOpp (>8h) for O/S vs. IP format (IP=40.0%, O/S=58.8%); when school started at/after 8:30am, sufficient SlpOpp was even more common (IP=52.7%, O/S=72.7%). Greater night-to-night variability was found for WT and SlpOpp for students with hybrid schedules with >1 day IP and >1 day online vs virtual schedules (O/S and O/A only), with no differences in BT variability reported between groups.ConclusionThis large study of diverse adolescents from across the U.S. found scheduled school start times were associated with early wake times and shorter sleep opportunity, with greatest variability for hybrid instruction. Study results may be useful for educators and policy makers who are considering what education will look like post-pandemic.Support (if any):

634 Impact of Changing School Start Times on Drowsy Driving and Teen Motor Vehicle Crashes: A Longitudinal Examination

Abstract Introduction Early high school start times are associated with insufficient adolescent sleep, which in turn is associated with motor vehicle crashes [MVC]. This analysis examined the impact of a 70-minute delay in high school start times on student-reported drowsy driving and department of transportation MVC rates before and for 2 years after start time changes. Methods Self-reported sleep duration and drowsy driving data were drawn from a longitudinal study of changing high school start times (n=2099–4092/year) in the Cherry Creek School District (Arapahoe County [AC]). The Colorado Department of Transportation provided frequency/timing of weekday MVC data for teen (16–18 years) and adult drivers in AC and four neighboring counties in metro Denver (Other Counties [OC]). MVC rates per 1000 licensed drivers were calculated. Outcomes are reported for three school years: 2016–17 (pre-change), 2017–18 (post change), and 2018–19 (follow-up). Chi-square analyses examined drowsy driving frequency (at least once/week vs. less than once/week) by sufficient weeknight sleep duration (&amp;lt;8 hours vs. 8+ hours). Two-proportion z-tests compared MVC rates by county, as well as teens vs. adults. Results Compared to pre-change (29.3%), fewer students reported drowsy driving at post-change (20.3%) and follow-up (23.7%). Students who reported insufficient sleep also reported more frequent drowsy driving across all years (p’s&amp;lt;0.001 to 0.037). AC’s teen crash rate decreased from 78.9/1000 to 76.6/1000 post-change, with a further reduction to 68.7/1000 at follow-up. Pre-change crash rates did not differ between counties (p=0.444); however, they were significantly lower in AC vs. OC at both post-change (p=0.048) and follow-up (p=0.046). Adult crash rates remained consistent over three years in both counties. Morning crash rates per hour did not differ pre-change; at both post-change and follow-up OC’s morning crash rates peaked one hour earlier than AC’s (7:00-7:59am vs. 8:00-8:59am). Conclusion This study extends previous reports by finding that later school start times are associated with decreased drowsy driving and fewer teen motor vehicle crash rates for up to 2 years post-change. Early school start times is an important public policy that benefits adolescent sleep, health, and well-being through decreased drowsy driving and motor vehicle crashes. Support (if any) Robert Wood Johnson Foundation’s Evidence for Action Program

238 Adolescent Sleep Variability, Social Jetlag, and Mental Health during COVID-19: Findings from a Large Nationwide Study

IntroductionAdolescents are vulnerable to short, insufficient sleep stemming from a combined preference for late bedtimes and early school start times, and also circadian disruptions from frequent shifts in sleep schedules (i.e., social jetlag). These sleep disruptions are associated with poor mental health. The COVID-19 pandemic has impacted education nationwide, including changes in instructional formats and school schedules. With data from the Nationwide Education and Sleep in TEens During COVID (NESTED) study, we examined whether sleep variability and social jetlag (SJL) during the pandemic associate with mental health.MethodsAnalyses included online survey data from 4767 students (grades 6-12, 46% female, 36% non-White, 87% high school). For each weekday, participants identified if they attended school in person (IP), online-scheduled synchronous classes (O/S), online-no scheduled classes (asynchronous, O/A), or no school. Students reported bedtimes (BT) and wake times (WT) for each instructional format and for weekends/no school days. Sleep opportunity (SlpOpp) was calculated from BT and WT. Weekday night-to-night SlpOpp variability was calculated with mean square successive differences. SJL was calculated as the difference between the average sleep midpoint on free days (O/A, no school, weekends) versus scheduled days (IP, O/S). Participants also completed the PROMIS Pediatric Anxiety and Depressive Symptoms Short Form. Data were analyzed with hierarchical linear regressions controlling for average SlpOpp, gender, and school-level (middle vs high school).ResultsMean reported symptoms of anxiety (60.0 ±9.1; 14%≧70) and depression (63.4 ±10.2; 22%≧70) fell in the at-risk range. Shorter average SlpOpp (mean=8.3±1.2hrs) was correlated with higher anxiety (r=-.10) and depression (r=-.11; p’s<.001) T-scores. Greater SlpOpp variability was associated with higher anxiety (B=.71 [95%CI=.41-1.01, p<.001) and depression (B=.67 [.33-1.00], p<.001) T-scores. Greater SJL (mean=1.8±1.2hrs; 94% showed a delay in midpoint) was associated with higher anxiety (B=.36 [.12-.60], p<.001) and depression (B=.77 [.50-1.03], p<.001) T-scores.ConclusionIn the context of system-wide education changes during COVID-19, students on average reported at-risk levels of anxiety and depression symptoms which were associated with greater variability in sleep opportunity across school days and greater social jetlag. Our findings suggest educators and policymakers should consider these sleep-mental health associations when developing instructional formats and school schedules during and post-pandemic.Support (if any)T32MH019927(P.W.)

647 Adolescent and Young Adult Sleep and Sleep-Related Behaviour Change During the COVID-19 Pandemic

IntroductionSleep disturbance, poor sleep quality, and dissatisfaction with sleep are common among adolescents and young adults (AYAs; e.g., Becker et al., 2018; Hicks et al., 2002; Hysing et al., 2013). Environmental and behavioural factors (e.g., early school start times, evening technology use and social pressures) are barriers to healthy sleep among AYAs that contribute to a “perfect storm” of sleep disturbance during this period (Carskadon, 2011; Crowley et al., 2018). Notwithstanding, few AYAs have access to sleep treatments. The COVID-19 pandemic lockdowns decreased academic and scheduling demands, providing an opportunity to study unconstrained AYA sleep and potentially facilitating better access to sleep interventions (Simpson & Manber, 2020). This study evaluated differences in baseline sleep and sleep-related behaviour change (i.e., how AYAs use an evidence-based app for sleep disturbance) before vs. during the lockdown.MethodsParticipants between the ages of 15 and 24 (M=20.66, SD=2.38) completed a 4-week feasibility study evaluating a free, transdiagnostic sleep self-management app (DOZE) before the lockdown (“Pre-Lockdown”; n=51) or during the lockdown (“Lockdown”; n=29). After 2 weeks of completing baseline sleep diaries, participants could set goals based on feedback and access tips, followed by 2 more weeks of completing sleep diaries.ResultsCompared to Pre-Lockdown, Lockdown demonstrated less variability in their sleep schedules (ps≤.011), less napping (p=.002), but increased time in bed (TIB; p<.001) and total wake time (p=.007). Total sleep time, lingering in bed in the morning, and sleep efficiency did not differ between groups. Relative to Pre-Lockdown, Lockdown showed a greater tendency to set goals to reduce schedule variability (p=.010) and to restrict excessive TIB (p=.005). Rates of goal setting for lingering in bed in the morning, sleepiness, naps, and sleep-interfering substance use did not differ between groups. Rates of accessing tips did not differ between groups.ConclusionEffects of COVID-19 lockdown on AYA sleep included less variability in their schedule and a decreased need for naps, but negative effects on TWT and TIB. As a result, AYAs set different goals during the COVID-19 lockdowns, focusing more on restricting excessive TIB than on schedule variability.Support (if any)Canadian Institutes of Health Research eHealth Innovation Partnership Program (#143551).

674 Changes in Objectively-Measured Adolescent Sleep and Light Exposure During the COVID-19 Pandemic

IntroductionU.S. adolescents have high rates of insufficient sleep. School closures and stay-at-home orders were implemented to mitigate disease spread during the Coronavirus 2019 (COVID-19) pandemic. Without the restriction of imposed early school start times, we hypothesized that adolescents would have longer, later, and less variable sleep compared to pre-COVID-19. We further hypothesized these changes would be associated with increased and later light exposure.MethodsHigh school students age 14–19 years with <7h sleep on school nights completed two weeks of at-home monitoring. The Pre-COVID-19 week took place between October 2018-February 2020 and the COVID-19 week occurred in May 2020 during state-wide stay-at-home orders. Participants wore an accelerometer to assess sleep and light exposure while completing a concurrent sleep log. Paired-samples t-tests examined differences in sleep and light between Pre-COVID-19 and COVID-19. Pearson correlations assessed associations between change in sleep and change in light.ResultsParticipants (N=16) were 16.5 ±1.2-years-old at Pre-COVID-19, 70.6% female, 68.8% White, and 25.1% Hispanic. Youth were participating in online learning due to in-person school closures and only 2 participants (14.3%) had a set start time, while the remainder reported learning per their own schedule. Youth obtained approximately one hour more weekday sleep per night during the COVID-19 week compared to Pre-COVID-19 (p<0.001). Bed and waketimes were significantly delayed on weekdays and weekends during COVID-19 compared to Pre-COVID-19 (p< 0.01). The greatest change was a delay in weekday waketime of 2.9□0.9h (p<0.001). Social jetlag during COVID-19 was reduced by 1/3 compared to Pre-COVID-19 (p=0.02). Average 24h lux levels were 2.5x higher during the COVID-19 week compared to Pre- COVID-19 (p=0.008). Change in average lux and timing of light were not significantly associated with change in sleep duration or timing.ConclusionAn unintended effect of the switch to online learning may have been affording adolescents the opportunity to obtain longer and more regular sleep. Understanding the impact of these changed sleep behaviors on daytime functioning, academic performance, and health outcomes is particularly urgent as schools plan for the remainder of the academic year and eventual return to in-person learning.Support (if any)K23DK117021 to SLS

687 Changes in adolescent sleep habits during the COVID-19 pandemic

IntroductionDuring the COVID-19 pandemic, adolescents have experienced significant lifestyle changes. With an increase in technological dependency and changes in school formats, sleep behaviors may be altered. As individuals with overweight or obesity (OWOB) already report higher rates of sleep issues, they may be particularly at risk during this time. However, to date, there are no data on changes in sleep behavior in adolescents with OWOB during the COVID-19 pandemic.MethodsParticipants included 10 adolescents with BMI ≥85th percentile (Mage=16.30 years, SDage=1.06; 60% male; 70% African American). Prior to the COVID-19 pandemic, participants completed sleep diaries twice per day for one week, noting caffeine intake, bedtime, naps, perceived sleep quality, and media use in bed. Participants then completed sleep diaries again during the COVID-19 pandemic. Five separate paired-samples t-tests assessed differences in sleep behaviors and quality.ResultsA paired-samples t-test demonstrated significantly earlier average bedtime before (M=11:20 PM, SD=55.16 minutes) than during (M=12:29 AM, SD=71.27 minutes) COVID-19 (t(9)=-3.0, p=0.015). A second paired-samples t-test demonstrated lower average media use in bed before (M=11.67, SD=10.97 minutes) than during (M=32.13, SD=27.28 minutes) the COVID-19 pandemic (t(9)=-2.3, p=0.050). No other significant differences were found.ConclusionAdolescents engaged in later bedtimes and increased media use in bed during the COVID-19 pandemic. This suggests adolescents’ sleep schedules have shifted later during the COVID-19 school year, due to either later wake times associated with virtual schooling or disruption in typical daily schedule as a result of the pandemic. However, no differences were found regarding caffeine intake, number of naps, and sleep quality. The significant findings regarding later adolescent bedtimes may reflect delayed sleep phase or possibly improved circadian alignment due to delayed school start times and at-home classes. The null findings regarding naps and caffeine intake may be reflective of the stability of daytime sleepiness. While we would expect daytime sleepiness to improve with increased circadian alignment, the effects may be diminished by increased media use in bed and decreased energy expenditure during the day. Given the observed relationships, current sleep hygiene interventions may require a focus on stimulus control and reducing time with media in bed.Support (if any):

Changing school start times: impact on sleep in primary and secondary school students.

Study ObjectivesTo examine the impact of changing school start times on sleep for primary (elementary school: ES) and secondary (middle and high school: MS/HS) students.MethodsStudents (grades 3–12) and parents (grades K-12) were surveyed annually, before and for 2 years after school start time changes (ES: 60 min earlier, MS: 40–60 min later; HS: 70 min later). Student sleep and daytime sleepiness were measured with school-administered student surveys and parent-proxy online surveys.ResultsApproximately 28,000 students annually completed surveys (~55% White, ~21% free/reduced lunch [FRL]). One-year post-change, weekday bedtimes and wake times were slightly earlier for ES students, with an 11-min decrease in sleep duration. MS and HS students reported slightly later weekday bedtimes, significantly later wake times, and significantly longer sleep duration (MS: 29 min; HS: 45 min). The percent of ES students reporting sufficient sleep duration, poor sleep quality, or daytime sleepiness did not change, but the percent of MS and HS students reporting sufficient sleep duration significantly increased and clinically significant daytime sleepiness decreased. All results were maintained at the 2-year follow-up. Benefits of later start times were similar across racial and free/reduced lunch groups.ConclusionsThis is the first large scale, longitudinal, and representative study to concurrently examine the impact of changing school start times across students in primary/secondary school. Findings suggest a minimal impact of earlier start times on ES students’ sleep or daytime sleepiness, while further supporting the significant benefits of delaying MS and HS start times on student sleep and daytime sleepiness.

COVID-19 and sleep patterns in adolescents and young adults

ObjectiveIn 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. MethodsAn 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. ResultsA 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. ConclusionsThe 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.).

Sleep Duration, Bedtime Consistency, and School Readiness: Findings from the 2016 to 2018 National Survey of Children's Health.

The focus of this study is to assess the link between sleep duration, bedtime consistency, and school readiness among a nationally representative sample of preschool-age children in the United States. A sample of 15,402 preschool-age children (3 to 5 years old) from the 3 most recent cohorts (2016-2018) of the National Survey of Children's Health was used. Information about sleep duration, bedtime consistency, and school readiness was obtained from surveys administered to primary caregivers. Four distinct domains of school readiness were examined: early learning skills, self-regulation, social-emotional development, and physical health and motor development. The findings reveal that children who obtain 7 or fewer hours of sleep per night exhibit significant reductions in school readiness both within and across all 4 domains. Similar but more modest patterns emerge among children with inconsistent bedtimes. Given the potential implications of young children's sleep for school readiness, pediatricians should be prepared and trained to effectively counsel parents about children's sleep patterns during routine well-child visits. Future research should examine whether improvements in sleep hygiene education for parents, behavioral sleep interventions, and/or later school start times once children enter preschool might enhance school readiness by improving children's health and well-being as they enter school.

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

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. 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. 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. 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.

Comparative analysis of sleep patterns and attention components in high school and college adolescents.

Adolescence is a phase with physiological and behavioral changes. One of them occurs in the sleep-wake cycle pattern, manifested by a phase delay. However, morning school start time can decrease sleep duration during weekdays, impairing adolescent cognitive performance and well-being. Adolescents of different ages and educational level might suffer the impact of academic demand on sleep-wake cycle and cognition differently. Thus, the aim of this study is to compare the sleep habits and quality, sleepiness upon awakening and attention components among adolescents in the first years of high school and college. 71 adolescents participated in the study (45 girls and 26 boys), 44 enrolled in high school morning classes (G1 - 15.5±0.7 years), from a private school, and 27 college students enrolled in morning classes (G2 - 18.8±1.04 years), from biosciences courses from a public institution. The groups did not differ in bedtime, get up time, time in bed and sleep irregularity. However, both groups showed differences according to the day of the week, bedtime and get up time became later and time in bed extended on weekends. G1 presented worse sleep quality and regarding attention, showed higher percentage of omissions in all components and worse performance in sustained attention (ANOVA, p<0.05). The poorer sleep quality of high school adolescents and reduced attention may have a negative effect on school performance. Additional studies are needed to investigate the causes of these differences between these two educational levels.

Sleep habits and circadian preferences in school-aged children attending a Mexican double-shift school system

ObjectiveTo determine the differences between sleep habits and circadian preference in school-aged children attending a Mexican double-shift school system. MethodsThis cross-sectional study consisted of 400 elementary public-school children (mean age = 10.77, SD = 0.70 y, from fourth, fifth and sixth grades) in Reynosa, Tamaulipas, in northeastern Mexico. Attending a double-shift school system: 200 from the morning shift and 200 in the afternoon shift. Specific questions regarding sleep habits were collected and for circadian preference, the Morningness-Eveningness Scale for Children (MESC) was used. ResultsMultivariate analysis reported no sex differences. Children attending at the morning shift during weekdays rose earlier, reported shorter time in bed and earlier midpoint of sleep than those in the afternoon shift. On weekends, morning shift children went to bed later than afternoon shift. Morning shift reported greater social jetlag, shorter average sleep length and more sleep deficit than afternoon shift. During weekdays and weekends evening type children went to bed later, rose later and reported later midpoint of sleep. Also, evening type reported more social jetlag than morning types. ConclusionThis study suggests that early school start times can have a detrimental effect on Mexican children. Moreover, the morning shift children may be at more risk of poor health due to the higher social jetlag, as well as a higher tendency to be sleep deprived. On the other hand, the afternoon shift represents an important social environment that allows children to follow their natural physiological needs and a more optimal sleep health.

On the morning commute problem in a Y-shaped network with individual and household travelers

This paper examines the morning commute problem when both household commuters and individual commuters are considered in a Y-shaped network with two upstream links and a single downstream link. The household parents daily pass through an upstream bottleneck with a limited capacity before a school and drop off their children. Then, they traverse the downstream bottleneck common to both household and individual commuters and arrive at the workplace. We explore the effects of staggering policy, i.e., staggering work and school start times, on the distribution of traffic congestion and social welfare. We analytically solve all the equilibrium cases and reveal all the traffic congestion patterns. The results reveal that the staggering policy may be harmful in certain cases. When the demand of individuals is relatively low, the staggering policy may not improve social welfare. When the demand of individuals is high, social welfare can be significantly improved if the schedule gap between work start time and school start time is optimized. The effects of the staggering policy on system performance are examined. We derive a Pareto frontier, which provides a good candidate set for the optimal staggering policy. Our results show that the optimal staggering policy on system performance depends on the demand distribution of the two groups. When the demand of individuals is high, there exists a unique optimal staggering policy that minimizes system performance. However, when the demand of individuals is low, the optimal staggering policy should be selected from the Pareto frontier. Furthermore, we re-examine the capacity expansion paradox under the staggering policy. Our study shows the capacity expansion at the downstream bottleneck can always reduce the total system cost. However, the paradoxical phenomenon may arise when the capacity of the upstream bottleneck is expanded, but it can be eliminated if the schedule gap is properly designed.

Normal Sleep in Children and Adolescence.

Adequate sleep is essential for healthy development in childhood and adolescence. Healthy sleep contributes to good physical health, immune function, mental health, and academic performance. The regulation and architecture of sleep change greatly across childhood and adolescence, and the ability to obtain sufficient sleep is impacted by a range of factors that change with maturation. This article describes normal sleep across childhood and adolescence and discusses some of the most common barriers to adequate sleep, including early school start times, technology use, and changes to circadian rhythms, and sleep homeostasis across puberty.

School start time: a public health crisis.

Citation:Sheldon SH, Pelayo R. School start time: a public health crisis. J Clin Sleep Med. 2020;16(suppl_1):11S–12S.

Does a delayed school start time cause students to exercise less? Evidence from South Korea

A delayed school start time (DSST), achieved by removing zero period, could change students’ other time use during school as well as other forms of human capital accumulation. Using difference-in-differences, we find evidence that a DSST in South Korea reduced the time students spent in gym class without worsening students’ health status. Combined with previous studies that provided evidence that DSSTs increased students’ test scores, our results imply that a DSST can increase students’ academic achievement without reducing other forms of human capital accumulation, although schools might change students’ other time use.

Perceived Barriers and Facilitating Factors in Implementing Delayed School Start Times to Improve Adolescent Sleep Patterns.

Most adolescents in the United States do not obtain sufficient sleep. Early school start times play a significant role in adolescent sleep deprivation. Most primary and secondary schools begin classes earlier than the 8:30 am. Perceived barriers to implementing a delayed school start time have been suggested in the literature but have not been quantified. This study explored perceived barriers and facilitating factors for implementing delayed high-school start times. A cross-sectional study. School administrators who had delayed their school start times were invited to complete an online questionnaire ranking the perceived barriers and facilitating factors for implementing the delayed start times. Most commonly cited perceived barriers were lack of a tiered bus system, school athletes missing more afternoon classes, and less time after school for athletics. Most commonly cited facilitating factors were school-administrator involvement in the decision-making process and sleep education for family members and school administrators. Participants found that providing sleep education to fellow administrators, teachers, school staff members, families, and students and including them in the decision-making process positively facilitated the implementation of delayed school start times. Perceived barriers to implementation may be overcome with support from stakeholders and planning committees.