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ABSTRACT Background Methods Results Implications Conclusions We aimed to characterize relationships between delayed high school start time policy, which is known to lengthen school night sleep duration, and patterns in activity outcomes: physical activity, non‐school electronic screen time (non‐schoolwork), and sports and extracurricular activity among adolescents.We used data from the START study, a multi‐site evaluation of a natural experiment, assessing the effects of a school start time policy change in high schools in the Minneapolis, Minnesota metropolitan area. The study follows students in 2 schools that shifted to a later start time (8:20 or 8:50 am) after baseline year and 3 schools that maintained a consistent, early start time (7:30 am) over the 3‐year study period. Activity was measured by participant self‐report on an in‐school survey. The analysis used a difference‐in‐differences estimator, in which the changes in each outcome observed in the comparison schools estimate the changes in each outcome that would have been observed in the late‐start adopting schools had they not delayed their start times after baseline.Over 2 years of follow‐up, no changes emerged to suggest that later school start times either interfered with, or promoted, any activity‐related outcome that was measured.Communities interested in promoting sleep by delaying start times may do so knowing that there are unlikely to be adverse effects on adolescent physical activity, electronic screen time, or organized sports and activity participation.A shift to later school start times does not appear to enhance or detract from the healthfulness of students' activity level. [ABSTRACT FROM AUTHOR]

Late chronotypes and early school start times are associated with unhealthy sleep habits during adolescence. Here we examine the impact of the relationship between school timing and chronotype on sleep quality in 349 Argentinian high-school students (age: 17-18 y.o., 49% females) randomly assigned to attend school in the morning, afternoon or evening. Students completed the Munich Chronotype Questionnaire and ranked their sleep quality using a Likert-like scale. We found higher sleep quality on free days than on weekdays. Importantly, morning-attending students showed lower sleep quality on weekdays. Finally, the interaction between school timing and chronotype was associated with sleep quality on weekdays: later chronotypes were associated with poorer sleep quality in morning- and afternoon-attending students, but not in the evening. Altogether, our results suggest that attending school in the morning is associated with shorter sleep duration and higher social jetlag, but also with lower sleep quality during adolescence.

Healthy sleep is defined by the combination of adequate duration, good quality, and regular timing. In children, sleep thus depends on the interplay of individual, parental, organizational, community, and social variables, but only a few studies have addressed this issue in a comprehensive way nationwide. Using the Uruguayan nationally representative survey (Nutrition, Child Development, and Health Survey, Encuesta de Nutrición, Desarrollo Infantil y Salud, ENDIS), we present the first epidemiological characterization of chronobiological and sleep parameters in Latin American children. On average, Uruguayan urban children (n = 2437; 5−10-years old) showed quite late chronotypes (MSFsc = 03:53 ± 1:07), moderate misalignment (SJL = 1.0 ± 0.9 h), and adequate sleep duration (SDweek = 9.9 ± 1.0 h). Further, we show the substantial influence of school shift schedules on children's circadian typology and sleep patterns. Our results show that children attending the morning school shift have a higher risk of sleep problems than afternoon-school shift ones. The chronotype and sleep were earlier in morning-school shift children than in children attending the afternoon school shift. However, morning-school shift children had stronger misalignment, shorter sleep on school days, and a higher risk of chronic sleep deficit and non-healthy circadian misalignment (even worse in late chronotypes) than afternoon-shift children. This evidence points to the need of evaluating policies to reorganize school start times to prevent the negative effects that early schooling seems to have on children's sleep health, which has been neglected so far.

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

Introduction: Delaying high school start times extends adolescents' nightly sleep, but it is less clear how it affects educational outcomes. We expect links between school start time delays and academic performance because getting enough sleep is a key input to the cognitive, health, and behavioral factors necessary for educational success. Thus, we evaluated how educational outcomes changed in the 2 years following a school start time delay. Methods: We analyzed 2153 adolescents (51% male, 49% female; mean age 15 at baseline) from START/LEARN, a cohort study of high school students in the Minneapolis—St. Paul, MN, USA metropolitan area. Adolescents experienced either a school start time delay ("policy change schools") or consistently early school start times ("comparison schools"). We compared patterns of late arrivals, absences, behavior referrals, and grade point average (GPA) 1 year before (baseline, 2015–2016) and 2 years after (follow‐up 1, 2016–2017 and follow‐up 2, 2017–2018) the policy change using a difference‐in‐differences analysis. Results: A school start time delay of 50–65 min led to three fewer late arrivals, one fewer absence, a 14% lower probability of behavior referral, and 0.07–0.17 higher GPA in policy change schools versus comparison schools. Effects were larger in the 2nd year of follow‐up than in the 1st year of follow‐up, and differences in absences and GPA emerged in the second year of follow‐up only. Conclusions: Delaying high school start times is a promising policy intervention not only for improving sleep and health but for improving adolescents' performance in school. [ABSTRACT FROM AUTHOR]

Background: School timings could influence teens' sleeping patterns by interrupting their sleep or the timing of light can shift their biological clock. The COVID-19 pandemic has altered teens' sleeping schedule making it important to analyze the effects of long-term social distancing on adolescents' sleep and mood. Objectives: This study analyzes the effects of long-term social distancing, due to the COVID-19 pandemic, on their sleeping patterns and mood. Methods: In this cohort study, data from the 2018 -- 2020 Korea Youth Risk Behavior Web-based Survey (KYRBS) were used to compare teens' sleep patterns in 2020 with those in 2018 -- 2019. The primary outcomes of this study were the sleep duration and sleep time of adolescents throughout the week, between 2018 and 2019, and in 2020. The secondary outcomes were the teens' mood, health perception, and sleep satisfaction, including differences in total sleep time and sleep discrepancies between weekends and weekdays. Results: Around 58 -- 63 thousand students were surveyed each year, and the participation rate was 94.9 -- 95.6%. After exclusion, 132,839 teens participated in the survey. From 2018-2020, the height and body weight of the participants did not change. After adjusting for participants' sex and school year, it was found that more teens felt happy, fewer teens experienced sadness and desperation, and fewer teens had suicidal thoughts in 2020, compared with the previous two years. They also slept 10 minutes later (9.743 (95% confidence interval 7.954 - 11.530)), with wake-up times of 3 -- 5 minutes later on weekdays (4.684 (3.449 - 5.919)). On weekends during social distancing, they slept 16 minutes later (15.721 (14.077 - 17.366)), with wake-up times of 12 minutes later (12.309 (10.393 - 14.225)). Although they slept five minutes less on weekdays (-5.059 (-6.817 to -3.301)) and three minutes less on weekends (-3.413 (-5.419 to -1.407)), their overall sleep satisfaction increased, and differences in sleep duration between weekdays and weekends decreased in 2020. Conclusions: During social distancing, the mood and sleep efficiency of teens improved. In the future, once the COVID-19 pandemic subsides, online classes can be included in the curriculum of school systems to ensure healthy sleep patterns in teenagers. [ABSTRACT FROM AUTHOR]

Adolescents' conflict between circadian rhythm and early school start time is more pronounced in evening chronotypes, who tend to reduce sleep duration during school days compensating during the free days by oversleeping (i.e., social jetlag). Cumulative weekly sleep debt may impair sport performance, which relies on physical and cognitive skills modulated by sleep. We hypothesized that chronotype predicts sport performance, and that it may interact with the day of the week. Moreover, given the role sleep plays in motor memory consolidation, we tested the hypothesis that school attendance, and the related chronic sleep deprivation, might be detrimental for participants in a training phase. Ninety-three adolescent male basketball players performed multiple free throw sessions (n = 7880) during both the school and holiday periods. Chronotype and its interaction with the day of the week significantly predicted shooting accuracy when attending school, but not on holidays. Evening types' performance gradually decreased from Monday to Friday. Participants with a more unstable performance (i.e., who did not complete the acquisition of the free throw motor scheme) worsened their accuracy when attending school. Our results suggest that the impact of chronotype and day of the week on sport performance is related to the presence of an externally imposed sleep/wake schedule and is consistent with evening types' increased likelihood of experiencing social jetlag. Possibly due to early school start time, attending school worsened the performance of participants in a training phase. Further investigations are required to assess whether reducing the mismatch between biological and social clocks might improve sport performance, along with other aspects of adolescents' life. [ABSTRACT FROM AUTHOR]

IntroductionShorter and/or disrupted sleep during adolescence is associated with cognitive and mental health risks, particularly in females. We explored the relationship between bedtime behavior patterns co-varying with Social Jet Lag (SJL) and School Start Times (SST) and neurocognitive performance in adolescent female students.MethodsTo investigate whether time of day (morning vs. afternoon), early SSTs and days of the school week can be correlated with neurocognitive correlates of sleep insufficiency, we recruited 24 female students aged 16–18 to report sleep logs, and undergo event-related electroencephalographic recordings on Monday, Wednesday, mornings, and afternoons. Using a Stroop task paradigm, we analyzed correlations between reaction times (RTs), accuracy, time of day, day of week, electroencephalographic data, and sleep log data to understand what relationships may exist.ResultsParticipants reported a 2-h sleep phase delay and SJL. Stroop interference influenced accuracy on Monday and Wednesday similarly, with better performance in the afternoon. For RTs, the afternoon advantage was much larger on Monday than Wednesday. Midline Event-Related Potentials (ERPs) yielded higher amplitudes and shorter latencies on Wednesday morning and Monday afternoon, in time windows related to attention or response execution. A notable exception were delayed ERP latencies on Wednesday afternoon. The latter could be explained by the fact that delta EEG waves tended to be the most prominent, suggesting heightened error monitoring due to accumulating mental fatigue.DiscussionThese findings provide insights into the interaction between SJL and SST and suggest evidence-based criteria for planning when female adolescents should engage in cognitive-heavy school activities such as tests or exams.

BACKGROUND: The benefits of delaying school start times for secondary students are well‐established. However, no previous study has considered how changing school start times impacts sleep and daytime functioning for K‐12 teachers. METHODS: Teachers in a large suburban school district completed 3 annual surveys (pre‐change n = 1687, post‐change n = 1857, follow‐up n = 1812) assessing sleep and daytime functioning. RESULTS: With delayed start times, high school teachers had later rise times (high school [HS]: 28 minutes, middle school [MS]: 14 minutes), increased sleep duration (HS: 22 minutes, MS: 13 minutes), and improved daytime functioning. Improvements for middle school teachers were noted but were not statistically significant. With earlier start times, elementary teachers reported earlier bedtimes (9 minutes) and wake times (9 minutes), with no changes in sleep duration or daytime functioning. IMPLICATIONS FOR SCHOOL HEALTH POLICY, PRACTICE, AND EQUITY: Today's school health policies often focus on wellness. Findings from this study reveal that the policy of healthy school start times can have a significant, positive impact on adults who teach in later‐starting secondary schools. Later school start times for secondary teachers provide greater parity with their elementary colleagues in terms of sleep opportunity. CONCLUSIONS: This study extends previous findings on how the policy of later secondary school start times improves the health and well‐being of adolescents, highlighting that healthy start times contribute to increased sleep opportunity for MS and HS teachers and improved daytime functioning for HS teachers, with changed start times having no significant negative effect on elementary school teachers. [ABSTRACT FROM AUTHOR]

There are numerous studies which show that an early school start time has a negative impact on the sleep, well-being, and academic performance of students. There is not enough information on the association between school start time and eating disorders, however: the disruption of the circadian rhythm is known to be a risk factor for eating disorders. The aim of this study is to analyze the relationship between school start time (SST) and the sleep, well-being, academic performance, and eating behavior of children and adolescents. The study was conducted in April and May 2021 in two regions of Russia: the Komi Republic and Yekaterinburg. The online study involved the anonymous and voluntary participation of 6571 students in grades 6–11 (mean age: 14.5 ± 1.6 years, 60.1% female), who have morning classes. All participants were divided into three groups according to SST: 08:00 (n = 3661), 08:30 (n = 2020), and 09:00 (n = 890). Each participant of the study indicated their place of residence, SST, age, sex, height, weight, academic performance, and filled out the Munich Chronotype Questionnaire, the Zung Self-Rating Depression Scale, and the Yale Food Addiction Scale for Children. As a result of multiple regression analysis, it was shown that schoolchildren with SST of 09:00 wake up at a later time on school days (B = 0.432; ΔR2 = 0.039), sleep more (B = 0.293; ΔR2 = 0.004), have less pronounced social jetlag (B = −0.223; ΔR2 = 0.005) and sleep loss (B = −0.292; ΔR2 = 0.005), and higher academic performance (B = 0.113; ΔR2 = 0.003) than schoolchildren with SST of 08:00. As a result of logistic regression analysis, it was found that the frequency of the detection of food addiction is ~30% lower in schoolchildren with SST of 09:00 (OR = 0.690; 95% CI = 0.485–0.981) than in their peers with SST of 08:00. Thus, an overly early SST in Russia has a negative impact on the sleep function, academic performance, and eating behavior of children and adolescents. [ABSTRACT FROM AUTHOR]

Keywords: school start time; sleep time; educational outcomes; time use EN school start time sleep time educational outcomes time use 439 474 36 07/21/22 20220701 NES 220701 1 Introduction Education fever of parents and severe competition among students to enter prestigious universities characterize education in East Asian countries, including South Korea ([8]; [17], [18]). [25] reports that the early morning self-study time in school is reduced or removed after the 9 O'clock Attendance Policy is implemented and that students' self-study time at school actually decreases. Schools in Gyeonggi eliminated the morning self-study time responding to the 9 O'clock Attendance Policy, and the students' self-study time decreased as a result ([25]). Figure 2 and Table 4 clearly show that the 9 O'clock Attendance Policy increases the sleep time of high school students. [Extracted from the article]

Introduction: Early school start times adversely influence adolescents' sleep duration. Late school start times and remote learning are associated with longer sleep durations. We leveraged a highly variable school schedule adopted after the first SARS-CoV-2 wave in Uruguay to study the influence of a hybrid mode of instruction (in-person/remote) with irregular school start times on adolescents' sleep.Methods: Objective sleep on school nights (120 observations) was determined using accelerometry recordings of 15 high-school students (3 males 15-17 years old). We used mixed-effects regressions to explore the influence of the mode of instruction (in-person/remote) and school start time on adolescents' sleep patterns (onset, end, and duration).Results: An irregular individual regime of 2-6 school days per week, either in-person or remote, and with irregular start times (range: 07:30-12:00) were observed during the studied period. Remote learning delayed sleep end by 48 ± 9 min and increased sleep duration by 36 ± 12 min. In addition, 1 h delay in school start time delayed sleep end in 36 ± 4 min and increased sleep duration in 34 ± 5 min.Conclusions: A strong linear association of the mode of instruction and the school start time with participants' sleep was observed: Only waking time was associated with both school start time and mode of instruction, and sleep duration increased when students were taught remotely and when school started later. These results add evidence to the effectiveness of delaying school start time to improve adolescents' sleep. However, these efforts may not overcome the influence of a very late circadian orientation, as observed in Uruguayan adolescents. [ABSTRACT FROM AUTHOR]

Valentina Alfonsi,1,2 Rossella Palmizio,3 Annalisa Rubino,3 Serena Scarpelli,2 Maurizio Gorgoni,1 Aurora D’Atri,4 Mariella Pazzaglia,1,2 Michele Ferrara,4 Salvatore Giuliano,3 Luigi De Gennaro1,2 1Department of Psychology, “Sapienza” University of Rome, Rome, Italy; 2I.R.C.C.S. Fondazione Santa Lucia, Rome, Italy; 3I.I.S.S. “Ettore Majorana”, Brindisi, Italy; 4Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L’Aquila, ItalyCorrespondence: Luigi De Gennaro“Sapienza” University of Rome, Via Dei Marsi, 78, Rome 00185, ItalyTel (+39) 06-49917647Fax (+39) 06-49917711Email luigi.degennaro@uniroma1.itPurpose: In adolescence, physiological (circadian and homeostatic regulation of sleep) and social habits contribute to delayed sleep onset, while social obligations impose early sleep offset. The effects of delayed school start time on the subjective/objective measures of sleep–wake patterns and academic achievement have not been established.Methods: This pre-, post-, and longitudinal non-randomized study included an early (8:00 am; ESC=30 students) and the late (9:00 am; LSC=21 students) start class. Multiple sleep data included a weekly sleep diary, Karolinska Sleepiness Scale, Pittsburgh Sleep Quality Index, and Epworth Sleepiness Scale. Sustained attention was measured using the Psychomotor Vigilance Task. Academic performance was evaluated by two different mathematical and scientific standard tests (entrance and final) and by school attendance indicators. Data were collected at monthly intervals from October 2018 to May 2019 and the beginning and end of the academic year (pre/post).Results: All students turned their lights off at similar times (LSC=11:21pm, ESC=11:11pm), but LSC students woke up later (7:23am) than ESC students (6:55am; F1,48=11.81, p=0.001) on school days. The groups did not differ in total sleep duration on non-school days. Longitudinal measures revealed a significant increase (8.9%, 34 min) in total sleep duration of LSC students across the academic year. ESC students maintained approximately the same sleep duration. Furthermore, changes in sleep duration had parallelled significant differences in sustained attention, with LSC students outperforming ESC students. Longitudinal changes of sleep and sustained attention were associated with a coherent pattern of changes in academic performance.Conclusion: Findings indicate that a one-hour delay in school start time is associated with longer sleep, better diurnal sustained attention, attendance, and improved academic performance. Notably, sleep changes were limited to school days. A delay in school start time should be seriously considered to improve sleep and academic achievements of students.Keywords: sleep, school start time, attention, school health, sleep loss, adolescence

Study Objectives: Our sleep extension intervention in adolescents showed that gradually shifting weekday bedtime earlier plus one weekend of morning bright light advanced circadian phase and increased weeknight sleep duration. Here, we examine at-home maintenance of these changes., Methods: Fourteen adolescents (15.3-17.9 years; 7 female) completed a 7-week study. After usual sleep at home (2-week baseline), intervention participants ( n  = 8) gradually advanced weekday bedtime (1 hour earlier than baseline during week 3; 2 hours earlier in week 4) and received bright light (~6000 lux; 2.5 hours) on both mornings of the intervening weekend. During three maintenance weeks, intervention participants were instructed to maintain their school-day wake-up time on all days, keep their early week four bedtimes, except on weekends when they could go to bed up to 1 hour later, and get a 2.5-hour light box exposure within 5 minutes of waking on one morning (Saturday or Sunday) of both weekends at home. Control participants ( n  = 6) slept as usual at home and did not receive weekend bright light. Dim light melatonin onset (DLMO) was measured after the 2-week baseline, 2-week intervention, and 3-week maintenance in all participants. Actigraphic sleep-wake was collected throughout., Results: After the 2-week intervention, DLMOs advanced more compared to control (37.0 ± 40.0 minutes vs. -14.7 ± 16.6 minutes), weekday sleep duration increased by 69.7 ± 27.8 minutes and sleep onset was 103.7 ± 14.2 minutes earlier compared to baseline. After three maintenance weeks, intervention participants showed negligible DLMO delays (-4.9 ± 22.9 minutes); weekday fall-asleep times and sleep durations also remained stable., Conclusions: Early circadian phase and extended sleep can be maintained with at-home weekend bright light., (© The Author(s) 2024. Published by Oxford University Press on behalf of Sleep Research Society.)

The insufficient amount of sleep adolescents are obtaining has been seen to have various negative effects on their academic performance and social wellbeing. Through a two-part, mixed method approach, a survey based upon the comprehensive sleep quality assessment—The Pittsburgh Sleep Quality Index—along with a voluntary interview, was provided to participants from two public high schools in the northeastern region of the United States. Each of the schools with differing starting times in order to determine the effects a delayed school start time has on high school students' sleep quality. Upon calculating the sleep scores of the participants of each school, it was found that students attending school with a later start time do have significantly better sleep quality than that of their peers from the earlier starting high school (p

Objective: To determine the differences between sleep habits and circadian preference in school-aged children attending a Mexican double-shift school system.Methods: This 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.Results: Multivariate 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.Conclusion: This 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. [ABSTRACT FROM AUTHOR]

This paper examines how delaying school start time to 9 o'clock affected the time use and health of secondary-school students in South Korea. To identify the causal effects of delaying school start time, we used a difference-in-differences methodology with two nationally representative datasets to take advantage of a unique natural experiment in South Korea. We found that the policy led students to sleep 16.1 min more on weekdays and 7.6 min less a day over the weekend, increasing sleep satisfaction among the affected students. Furthermore, the policy contributed to increased growth and improved mental health. However, the effects of the policy were not uniform across subgroups. In terms of time use, students from the highest socioeconomic group increased their sleep duration most. In contrast, students from the middle and lowest socioeconomic categories increased their use of electronic devices and decreased their study time compared to students from the highest socioeconomic group. We provide evidence that these behavioural differences by socioeconomic group could be related to the degree of parental monitoring and available economic resources. [ABSTRACT FROM AUTHOR]

The delayed circadian timing of adolescents creates a conflict with early school start times (SSTs). We used wrist actimetry to compare sleep parameters and routine nighttime activities in middle school students attending either a morning (0700 to 1200 h) or an afternoon (1230 to 1730 h) school shift. On school days, students from both shifts (n = 21 for morning shift, n = 20 for afternoon shift, ages 12-14 years) had a similar sleep onset, but morning-shift students had an earlier sleep offset and a 1 h 45 min shorter sleep duration than their afternoon peers, who slept the recommended 8 to 10 h of daily sleep. Only morning-shift students had afternoon naps, but this afternoon sleep was not sufficient to overcome sleep deprivation. On weekends, sleep onsets and offsets did not differ between shifts. Because only morning-shift students woke up later and slept longer (2 h 3 min) on weekends, they were also the only ones who experienced social jetlag. Daily surveys on their nighttime (from 1800 to 0600 h) activities indicated there was no difference between shifts in the time spent on leisure or using electronic media during school days, but students from both shifts spent more time in these activities during the weekend. Our study confirms that early SST in adolescents is associated with sleep deprivation and suggests that schedules that start much later than typically considered may be needed to eliminate sleep deprivation in adolescents. [ABSTRACT FROM AUTHOR]

Healthy sleep is defined by the combination of adequate duration, good quality, and regular timing. In children, sleep thus depends on the interplay of individual, parental, organizational, community, and social variables, but only a few studies have addressed this issue in a comprehensive way nationwide. Using the Uruguayan nationally representative survey (Nutrition, Child Development, and Health Survey, Encuesta de Nutrición, Desarrollo Infantil y Salud, ENDIS), we present the first epidemiological characterization of chronobiological and sleep parameters in Latin American children. On average, Uruguayan urban children (n = 2437; 5-10-years old) showed quite late chronotypes (MSFsc = 03:53 ± 1:07), moderate misalignment (SJL = 1.0 ± 0.9 h), and adequate sleep duration (SDweek = 9.9 ± 1.0 h). Further, we show the substantial influence of school shift schedules on children's circadian typology and sleep patterns. Our results show that children attending the morning school shift have a higher risk of sleep problems than afternoon-school shift ones. The chronotype and sleep were earlier in morning-school shift children than in children attending the afternoon school shift. However, morning-school shift children had stronger misalignment, shorter sleep on school days, and a higher risk of chronic sleep deficit and non-healthy circadian misalignment (even worse in late chronotypes) than afternoon-shift children. This evidence points to the need of evaluating policies to reorganize school start times to prevent the negative effects that early schooling seems to have on children's sleep health, which has been neglected so far., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)

Objective: Later school start times for adolescents have been implemented in the US and associated benefits found, although no randomised controlled trials (RCT) have been undertaken. The objective of this study was to evaluate the impact of two school interventions in the UK, a delayed start time and a sleep education programme, on students' academic performance, sleep outcomes and health-related quality of life.Methods: The study had an RCT design to enable an investigation into the differential effects of two interventions or a combination of both: schools were to delay their start time to 10:00am and/or provide a classroom-based sleep education programme. The recruitment target was 100 state (non-fee-paying) secondary schools. Participants were to be students in Year 10/11 (14-16-year-olds).Results: Despite much media coverage, only two schools volunteered to take part in the RCT. The main challenges faced in recruitment fell under three categories: research design, school, and project-specific issues. The delayed start time and prospect of randomisation to this intervention were the overwhelming reasons cited for not taking part. Facilitators and barriers to research were identified. Recommendations include carrying out a feasibility study prior to a main trial, allowing adequate time for recruitment, involving stakeholders throughout the decision-making process, incorporating independent (fee-paying) schools in recruitment, focusing on students not taking important examinations or involving an older year group with greater independence.Conclusion: The Teensleep study provides supporting evidence that evaluating the effects of a change in school start times through an RCT is unfeasible in the UK. [ABSTRACT FROM AUTHOR]

Objective: To investigate associations between sleep duration and health-related measures, and factors associated with short sleep, in adolescents in an East Asian society with strong emphasis on academic achievement.Methods: Adolescents aged 13-19 years (n = 2346) from eight schools in Singapore (five local, three international) took part in a cross-sectional survey of sleep habits, school life, and health. Self-rated health, overweight (International Obesity Task Force Criteria), and depression symptoms were compared in adolescents with short (<7 h), moderately short (7 to <8 h), or an appropriate amount of sleep (8-10 h) on school nights.Results: Short sleep on school nights was associated with poorer self-rated health, increased odds of being overweight (adjusted odds ratio [ORadj] = 2.56, 95% confidence interval = 1.39-4.70), and increased odds of feeling depression symptoms (sadness, irritability, worthlessness, low motivation, difficulty concentrating, anhedonia, anxiety, and thoughts of self-harm/suicide) compared with an appropriate sleep duration (ORadj = 2.10-4.33, p < 0.05 for each symptom). Barriers to healthy sleep included later preferred sleep timing (a relative indicator of later chronotype), lower parental supervision of bedtime, longer study time, early school start time, and longer travel time. Students at local schools were less likely to have a parent-set bedtime, and spent more time on homework/studying. Later bedtime in local schools attenuated the benefit of later school start time on nocturnal sleep duration.Conclusions: Short sleep may contribute to poorer adolescent health and well-being. Strategies for improving sleep in hard-driving East Asian societies should take into account sociocultural factors that may impede removal of barriers to healthy sleep. [ABSTRACT FROM AUTHOR]

Background: To date, no longitudinal population-based studies of school start times have been conducted within Canada. School schedule changes provided an opportunity to examine start times in association with youth sleep, physical activity, and screen use over time.Methods: This longitudinal study included grade 9-12 students attending 49 Ontario secondary schools that participated in at least two consecutive years of the COMPASS study (2012-2017). Fixed effects models tested whether differences in within-student change in self-reported sleep duration, moderate-to-vigorous physical activity, and screen time were associated with school start time changes, adjusting for student- (grade, sex, ethnicity, spending money) and school-level covariates (median income, urbanicity, geographical area).Results: Thirteen start time changes of 5-10 min were reported. Ten-minute advances at earlier clock times (8:30 AM-8:20 AM; 8:40 AM-8:30 AM) were associated with steeper sleep duration declines than schools with consistent start times but had no effect at later times (9:00 AM-8:50 AM). While sleep change did not differ with 5-min delays, 10-min delays (8:50 AM-9:00 AM) were associated with additional sleep (23.7 min). Apart from one school that shifted from 8:30 AM to 8:35 AM, in which screen time and physical activity decreased more steeply, no effect was found for screen time, and 5-min delays were associated with more physical activity (10.9 min) and advances with less activity (-8.0 min).Conclusions: Results support start time delays as a valuable strategy to help ameliorate sleep debt among youth. Interference with physical activity or increased screen time appear unlikely with modest schedule changes. Potential adverse impacts on sleep require consideration with 10-min advances. [ABSTRACT FROM AUTHOR]

During the outbreak of the COVID-19 pandemic in 2020, high schools closed or transitioned to remote teaching. The aim of this study was to describe how the COVID-19 related school shutdown impacted the sleep behaviors of typically developing adolescents. A qualitative study was conducted between April 28 and June 3, 2020 with 45 adolescents using one-on-one semi-structured phone interviews. The "natural experiment" caused by the shutdown of schools due to the COVID-19 pandemic led to a 2-h shift in the sleep of typically developing adolescents, longer sleep duration, improved sleep quality, and less daytime sleepiness compared to those experienced under the regular school-time schedule. These findings are consistent with previous studies showing that delaying high school start times could be an effective way to extend sleep duration, improve sleep quality, reduce daytime sleepiness and lower adolescents' stress during the school year. As many countries look for ways to reduce the number of interactions between students in schools so that physical distancing is feasible, following teens' delayed sleep biology could offer an affordable solution. For example, staggering arrival times by delaying school start time for older adolescents compared with younger adolescents can reduce the total number of students attending school at the same time. This strategy offers a practical means to reduce school density and the number of interactions between students which are needed to reduce the potential transmission of COVID-19 in schools, while improving adolescents sleep health. • Adolescents' sleep improved during the COVID19. • Adolescents' sleep schedule during the pandemic was 2 h later than during regular school times. • Delaying adolescents' school start time could help reduce transmission of COVID19. [ABSTRACT FROM AUTHOR]

Study Objectives: This study aimed to determine the sleep quality of in-school Nigerian adolescents and its association with their schooling and mental health outcomes., Methods: The study was a descriptive cross-sectional study. It was conducted among adolescents attending public and private secondary schools within the Ife Central Local Government, Osun State, southwestern Nigeria. A multistage sampling technique was used to select study participants. The Pittsburgh Sleep Quality Index, 9-item Patient Health Questionnaire (PHQ-9), and 7-item General Anxiety Disorder questionnaires were used to determine sleep quality, depression, and anxiety, respectively., Results: We studied 448 adolescents aged between 10 and 19 years with a mean age of 15.0 ± 1.8 years. The majority of our respondents (85.0%) had poor sleep quality. More than half of the respondents (55.1%) had insufficient sleep during weekdays, while only 34.8% had insufficient sleep during weekends. The school closing time and school type showed a statistically significant association with sleep quality ( P = .039 and .005, respectively). The odds of having poor sleep quality increased by 2-fold among adolescents in private schools when compared with those in public schools (adjusted odds ratio = 1.97, 95% confidence interval = 1.069-3.627). Using multiple linear regression, only depression showed a statistically significant association with sleep quality at 95% confidence interval (CI = 0.073 to 0.219, P < .001), such that for every unit change in depression scores (PHQ-9), there will be a corresponding increase of 0.103 in sleep quality., Conclusions: Sleep quality is poor in adolescents and adversely associated with their mental health. This should also be addressed in the development of appropriate interventions., Citation: Olorunmoteni OE, Fehintola FO, Seun-Fadipe C, Komolafe MA, Mosaku KS. Sleep quality and its relationship with school schedules and mental health of Nigerian secondary school adolescents. J Clin Sleep Med . 2023;19(11):1895-1904., (© 2023 American Academy of Sleep Medicine.)

The maturation of sleep regulatory systems during adolescence in combination with psychosocial and societal pressures culminate in a "Perfect Storm" of short and ill-timed sleep and the associated consequences for many youngsters. This model, first described by Carskadon in 2011, guides our current thinking of adolescent sleep behavior. Since the original description, the field has moved forward with remarkable pace, and this review aims to summarize recent progress and describe how this new work informs our understanding of sleep regulation and sleep behavior during this developmental time frame. [ABSTRACT FROM AUTHOR]

The effects of a delayed school start time by one hour were examined at a boarding school in Hong Kong. Two cohorts of high school students (N = 228; 61.8% female) were recruited respectively before and after a school start time changed from 7:30am to 8:30am. Both cross-cohort and within-cohort longitudinal comparisons yielded significant increase in total sleep time. Cross-cohort comparison yielded improvement in sleep quality, insomnia, life satisfaction, and psychological distress. Longitudinal data suggested that the longer the additional sleep time, the better was sleep quality, day-time functioning, and subjective wellbeing. [ABSTRACT FROM AUTHOR]

This study compared the effects of time spent on electronic media devices during nighttime before going to sleep on the sleep‐wake cycle, daytime sleepiness, and chronotype in 568 Mexican students (288 girls, mean age = 14.08) attending a double school shift system (287 from morning shift and 281 from afternoon shift). Students completed anonymous self‐report questionnaires. Results suggest that high exposure to an electronic media device may have an impact on their sleep‐wake cycle, regardless of their school shift. Adolescents from the afternoon shift reported more time spent on devices. Those from the morning shift reported daytime sleepiness with the use of MP3 player, and from the afternoon shift with the use of computer, MP3 player, and television. Both school shifts reported an intermediate chronotype with all electronic media devices, but the afternoon shift with a tendency towards eveningness with the use of the computer, smartphone, and MP3 player. [ABSTRACT FROM AUTHOR]

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. • Later high school start times did not reduce risk of weight gain for adolescents. • Later start times led to more favorable trajectories of weight-related behaviors. • Population-wide strategies that promote healthful sleep among teens are needed. [ABSTRACT FROM AUTHOR]

We sought to examine the effects of high school start time delay, a proven sleep-promoting intervention, on sugary beverage (SB) consumption among U.S. adolescents. In the Spring of 2016 (baseline), the START study recruited 2134 ninth grade students who were enrolled high schools in the Twin Cities, MN metropolitan area. These participants were surveyed again in their 10th and 11th grade years, in Spring 2017 and 2018 (follow-ups 1 and 2). All five high schools started early (7:30 or 7:45 a.m.) at baseline. By follow-up 1, two "policy change" schools shifted their start times later (8:20 or 8:50 a.m.) and maintained these later start times through follow-up 2 while three "comparison schools" retained an early start time at all time points. Generalized estimating equations using a negative binomial distribution were used to obtain estimates of the number of sugary beverages consumed per day at each wave as well as the difference in difference (DiD) estimates between baseline and each follow-up period comparing policy change to comparison schools. Mean baseline sugary beverage consumption was 0.9 (1.5) beverages per day in policy change schools and 1.2 (1.7) beverages per day in the comparison schools. While there was no evidence of impact of start time change on total SB consumption, DiD estimates revealed a small decrease in the number of caffeinated sugary beverages consumed between baseline and the second follow-up period in students attending the policy change schools relative to comparison schools in both crude (0.11/day reduction, p-value = 0.048) and adjusted analyses (0.11/day reduction, p-value = 0.028). Although the differences in this study were quite modest, a population-wide reduction in sugary beverage consumption could have public health benefit. [ABSTRACT FROM AUTHOR]

Older adolescents are particularly vulnerable to circadian misalignment and sleep restriction, primarily due to early school start times. Light can shift the circadian system and could help attenuate circadian misalignment; however, a phase response curve (PRC) to determine the optimal time for receiving light and avoiding light is not available for adolescents. We constructed light PRCs for late pubertal to postpubertal adolescents aged 14 to 17 years. Participants completed 2 counterbalanced 5-day laboratory sessions after 8 or 9 days of scheduled sleep at home. Each session included phase assessments to measure the dim light melatonin onset (DLMO) before and after 3 days of free-running through an ultradian light-dark (wake-sleep) cycle (2 h dim [~20 lux] light, 2 h dark). In one session, intermittent bright white light (~5000 lux; four 20-min exposures) was alternated with 10 min of dim room light once per day for 3 consecutive days. The time of light varied among participants to cover the 24-h day. For each individual, the phase shift to bright light was corrected for the free-run derived from the other laboratory session with no bright light. One PRC showed phase shifts in response to light start time relative to the DLMO and another relative to home sleep. Phase delay shifts occurred around the hours corresponding to home bedtime. Phase advances occurred during the hours surrounding wake time and later in the afternoon. The transition from delays to advances occurred at the midpoint of home sleep. The adolescent PRCs presented here provide a valuable tool to time bright light in adolescents. [ABSTRACT FROM AUTHOR]

At the onset of puberty, students shift their sleep to later hours, but school starts early. It is suggested that evening orientation and early school start times do not go well together. Therefore, the aim of this study was to investigate sleep problems in adolescence, and it was expected that the adolescents' eveningness orientation is associated with many sleep-related problems. Students of secondary education (n = 3201; mean = 13.8 ± 1.8 years) filled out a self-report questionnaire containing measures of morningness-eveningness, sleep time (midpoint of sleep, social "jetlag"), sleep length (on schooldays and on weekends), sleep quality, and sleep hygiene as well as questions on electronic screen media use. The impact of circadian preference on sleep time (midpoint of sleep and social jetlag), sleep length (on schooldays and on weekends), sleep quality, and sleep hygiene of adolescents was tested via multilevel analyses while controlling for covariates on the student level (age, sex, screen media use, and time leaving home) and on the class level (school type, grade level, and school start time). Morningness-eveningness was a significant predictor of all dependent variables and associations were highest (β > 0.40) for midpoint of sleep, social jetlag, problems with going to bed, problems with falling asleep, and problems with returning to wakefulness. Providing guidance for parents on sleep hygiene behavior routines for their child, an educational program in sleep hygiene, and later school start times could help to synchronize adolescents' circadian rhythms to daily educational and social demands. [ABSTRACT FROM AUTHOR]

Objective: To examine the effects of a modest delay (15 min) in school start time (SST) on adolescent sleep patterns, mood, and behaviors.Methods: Two secondary schools in Hong Kong with a total of 1173 students (intervention: n = 617; comparison school n = 556) completed both baseline and follow-up questionnaires. School start time was delayed by 15 min, from 7:45 a.m. to 8:00 a.m., in the intervention school. The comparison school maintained their regular SST at 7:55 a.m. Students' sleep-wake patterns, daytime sleepiness, and mental and behavioral aspects were assessed by validated questionnaires before and after the intervention.Results: Students in the intervention school significantly delayed their weekday wake-up time (p < 0.001) and increased their total time in bed (p < 0.001) when compared to students in the comparison school. Both groups experienced a delay in their weekday bedtime. The students in the intervention school showed improved mental health [General Health Questionnaire (GHQ) score, p = 0.015], better prosocial behaviors (p = 0.009), better peer relationships (p < 0.001), greater attentiveness (p < 0.001), less emotional problems (p = 0.002), and less behavioral difficulties (p < 0.001) as measured by Strengths and Difficulties Questionnaire (SDQ).Conclusions: A modest delay (15 min) in school start time can increase adolescent sleep with corresponding improvement in mood and behaviors. Current findings have significant implications for education policy, suggesting that school administrators and policy makers should systematically consider delaying school start time to promote sleep and health among school-aged adolescents.Clinical Trial Registration: ChiCTR-TRC-12002798. The trial protocol can be accessed at: http://www.chictr.org/en/proj/show.aspx?proj=3955. [ABSTRACT FROM AUTHOR]

Study Objectives: School start times impose constraints on sleep-wake timing that may influence academic achievement. We used large university archived datasets to test the hypothesis that larger differences in timing of students' diurnal learning behavior on school days relative to non-school days would be associated with lower grades., Methods: Diurnal learning-directed behavior was examined in 33 645 university students by analyzing their learning management system (LMS) login rhythm. We tested the associations between the phase-difference in students' behavioral rhythm on school days versus non-school days with grade point average, LMS-login phase on non-school days (LMS-login chronotype), and school start time. We also tested the chronotype-dependent effects of school start times on diurnal behavior to determine whether students obtained better course grades when their first class of the day was in synch with their LMS-login chronotype., Results: Students whose LMS-login rhythm was more than 2 hours earlier on school days had significantly lower grades than their peers. The change in LMS-login phase was larger in students with a later LMS-login chronotype and for earlier school start times. Minimal changes in LMS-login phase and higher course grades were observed when students' first class of the day was aligned with their LMS-login chronotype., Conclusions: Our findings demonstrate that school start times have a profound impact on students' diurnal learning behavior with implications for grades. Universities can potentially improve learning by starting school later to minimize differences in diurnal learning behavior between school days and non-school days., (© The Author(s) 2023. Published by Oxford University Press on behalf of Sleep Research Society.)

Introduction: Shorter and/or disrupted sleep during adolescence is associated with cognitive and mental health risks, particularly in females. We explored the relationship between bedtime behavior patterns co-varying with Social Jet Lag (SJL) and School Start Times (SST) and neurocognitive performance in adolescent female students., Methods: To investigate whether time of day (morning vs. afternoon), early SSTs and days of the school week can be correlated with neurocognitive correlates of sleep insufficiency, we recruited 24 female students aged 16-18 to report sleep logs, and undergo event-related electroencephalographic recordings on Monday, Wednesday, mornings, and afternoons. Using a Stroop task paradigm, we analyzed correlations between reaction times (RTs), accuracy, time of day, day of week, electroencephalographic data, and sleep log data to understand what relationships may exist., Results: Participants reported a 2-h sleep phase delay and SJL. Stroop interference influenced accuracy on Monday and Wednesday similarly, with better performance in the afternoon. For RTs, the afternoon advantage was much larger on Monday than Wednesday. Midline Event-Related Potentials (ERPs) yielded higher amplitudes and shorter latencies on Wednesday morning and Monday afternoon, in time windows related to attention or response execution. A notable exception were delayed ERP latencies on Wednesday afternoon. The latter could be explained by the fact that delta EEG waves tended to be the most prominent, suggesting heightened error monitoring due to accumulating mental fatigue., Discussion: These findings provide insights into the interaction between SJL and SST and suggest evidence-based criteria for planning when female adolescents should engage in cognitive-heavy school activities such as tests or exams., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 D’Angiulli, Byczynski, Yeh, Garrett, Goldfield, Devenyi, Devenyi and Leisman.)

School start time influences sleep parameters. Differences between circadian sleep parameters on weekends and weekdays have been associated with obesity, sleep, and psychiatric disorders. Moreover, circadian rhythm dysregulation affects the secretion of some hormones, such as melatonin and cortisol. In the current study, we investigate the effect of school start time on cortisol and melatonin levels in a community sample of Brazilian children and adolescents. This was a cross-sectional study of 454 students (mean age, 12.81 ± 2.56 years; 58.6% female). From this sample, 80 participants were randomly selected for saliva collection to measure melatonin and cortisol levels. Circadian sleep parameters were assessed by self-reported sleep and wake up schedules and the Morningness–Eveningness Questionnaire. The outcomes, salivary melatonin and cortisol levels, were measured in morning, afternoon and night saliva samples, and behavior problems were assessed using the Child Behavior Checklist (CBCL). The main results revealed that morning school start time decreased the secretion of melatonin. Morning melatonin levels were significantly positively correlated with the sleep midpoint on weekdays and on weekends. Afternoon melatonin levels were positively correlated with the sleep midpoint on weekends in the morning school students. Conversely, in the afternoon school students, night melatonin levels were negatively correlated with the sleep midpoint on weekdays. Cortisol secretion did not correlate with circadian sleep parameters in any of the school time groups. In conclusion, school start time influences melatonin secretion, which correlated with circadian sleep parameters. This correlation depends on the presence of psychiatric symptoms. Our findings emphasize the importance of drawing attention to the influence of school start time on the circadian rhythm of children and adolescents. [ABSTRACT FROM AUTHOR]

The Society of Behavioral Medicine recommends school officials start middle and high school classes at 8:30 AM or later. Such a schedule promotes students' sleep health, resulting in improvements in physical health, psychological well-being, attention and concentration, academic performance, and driving safety. In this position statement, we propose a four-tiered approach to promote later school start times for middle and high schools. [ABSTRACT FROM AUTHOR]

Study Objectives: Shift sleep onset earlier and extend school-night sleep duration of adolescents., Methods: Forty-six adolescents (14.5-17.9 years; 24 females) with habitual short sleep (≤7 h) and late bedtimes (≥23:00) on school nights slept as usual for 2 weeks (baseline). Then, there were three weekends and two sets of five weekdays in between. Circadian phase (Dim Light Melatonin Onset, DLMO) was measured in the laboratory on the first and third weekend. On weekdays, the "Intervention" group gradually advanced school-night bedtime (1 h earlier than baseline during week 1; 2 h earlier than baseline during week 2). Individualized evening time management plans ("Sleep RouTeen") were developed to facilitate earlier bedtimes. On the second weekend, Intervention participants received bright light (~6000 lux; 2.5 h) on both mornings. A control group completed the first and third weekend but not the second. They slept as usual and had no evening time management plan. Weekday sleep onset time and duration were derived from actigraphy., Results: Dim light melatonin onset (DLMO) advanced more in the Intervention (0.6 ± 0.8 h) compared to the Control (-0.1 ± 0.8 h) group. By week 2, the Intervention group fell asleep 1.5 ± 0.7 h earlier and sleep duration increased by 1.2 ± 0.7 h; sleep did not systematically change in the Control group., Conclusions: This multi-pronged circadian-based intervention effectively increased school-night sleep duration for adolescents reporting chronic sleep restriction. Adolescents with early circadian phases may only need a time management plan, whereas those with later phases probably need both time management and morning bright light., Clinical Trials: Teen School-Night Sleep Extension: An Intervention Targeting the Circadian System (#NCT04087603): https://clinicaltrials.gov/ct2/show/NCT04087603., (© The Author(s) 2022. Published by Oxford University Press on behalf of Sleep Research Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Sleep problems in adolescence have been identified as an international public health issue. Over the past few decades, notable advances have been made in our understanding of the patterns and consequences of sleep in adolescence. Despite these important gains, there is much about the role of sleep in adolescence that remains to be understood. This Special Issue brings together studies that examine sleep as it specifically pertains to adolescent development and adjustment. In this introductory article, we argue for the importance of grounding the study of sleep and adolescence in developmental science and a developmental psychopathology framework. First, a review of the literature is used to outline a biopsychosocial and contextual model of sleep in adolescence. Second, attention-deficit/hyperactivity disorder (ADHD) is used as an exemplar of the proposed model given the pervasiveness of sleep problems among youth with ADHD and the likelihood that sleep problems and ADHD symptoms are interconnected in complex ways. Finally, a brief introduction to the empirical articles included in the Special Issue is provided, with particular attention given to how these articles fit within the proposed biopsychosocial and contextual model. Along with the framework proposed in this article, the studies included in this Special Issue advance the current literature and point to critical directions for future research. [ABSTRACT FROM AUTHOR]

This study compared sleep patterns of high school students in 1999 and 2008. In 2006, school start times were delayed for senior students (years 12-13) from 09:00 to 10:30. For junior students (years 9-11), start time remained unchanged at 09:00. Questionnaires were completed at school by 212 year 9 and 12 students in 1999, and 455 year 9, 11 and 12 students in 2008. Year 12 students in 2008 were less likely to report sleep loss on school nights ( OR = 0.06, 95% CI = 0.01-0.11) and were less sleepy ( OR = 0.58, 95% CI = 0.34-0.98) than Year 12 in 1999 or than Year 11 in 2008, after controlling for gender (sleep loss, OR = 0.31, 95% CI = 0.19-0.53; sleepiness, OR = 0.46, 95% CI = 0.28-0.75). There were no comparable changes for Year 9 students. From 1999-2008, students having technologies in the bedroom rose from 80.7% to 96.4% ( P( χ2) < 0.001). In 2008, having more technologies was associated with less sleep on school nights ( Spearman's rho P = 0.005). In 2008, Year 9 students with more technologies were more likely to report daytime sleepiness ( OR = 4.06, 95% CI = 1.44-11.41) and being evening type ( OR = 3.38, 95% CI = 1.27-9.01), after controlling for gender. In 2008 all year groups went to bed earlier than in 1999, possibly due to increased sleep awareness, but only Year 12 students sleep later on school mornings. We conclude that delaying school start time had beneficial effects for Year 12 students, reducing sleep loss on school nights and daytime sleepiness. However, increased presence of technologies is associated with later sleep times and daytime sleepiness among Year 9 students. [ABSTRACT FROM AUTHOR]

The study's aim was to investigate how school start time affects sleepiness and functioning in Norwegian 10th grade students (N = 106). The intervention school started at 0930 hours on Mondays and 0830 hours the rest of the week. A control school started at 0830 hours all schooldays. The students were assessed on a reaction time test as well as with self-report measures of sleepiness, mood and sleep. The intervention school obtained one hour longer total sleep time on Sunday nights compared to the control school and performed better on the reaction time test on Mondays than on Fridays, relative to the control school. Later school start times may both lengthen nocturnal sleep and increase students' alertness in early morning classes. [ABSTRACT FROM AUTHOR]

A survey on sleep schedule, sleep health, school performance and school start times was conducted in 1,941 adolescents. A high level of early and circadian-disadvantaged sleep/wake schedules during weekdays was observed. Shorter sleep duration on weekdays was reported, especially in upper classmen. Complaints of inadequate sleep and sleepiness during weekdays, alarm clock use, and napping were prevalent. Night awakening and prolonged sleep onset were common and associated with poor school performance. Students with a sleep length of less than 7 hours on both weekdays and weekends exhibited poorer performance, while those who made up this sleep loss on weekends did not. The total number of poor sleep factors in an individual also correlated with poor school performance. Earlier school start times were associated with a perception of poor sleep quality, shorter sleep duration and more sleep health problems. We conclude that sleep inadequacies and sleep health problems were prevalent in this population, especially in those who started school earlier in the morning, and that these poor sleep factors were associated with school performance. [ABSTRACT FROM AUTHOR]

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., (Copyright © 2021 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.)