January 2025
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6 Reads
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January 2025
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6 Reads
November 2024
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27 Reads
Journal of School Health
Background 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. Methods 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. Results 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. Implications 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. Conclusions A shift to later school start times does not appear to enhance or detract from the healthfulness of students' activity level.
June 2024
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19 Reads
January 2024
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30 Reads
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2 Citations
Sleep Health
May 2023
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49 Reads
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3 Citations
Preventive Medicine
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.
March 2023
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29 Reads
Appetite
Objectives: 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. Methods: 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 AM) at baseline. By follow-up 1, two "policy change" schools shifted their start times later (8:20 or 8:50 AM) 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. Results: 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). Conclusion: Although the differences in this study were quite modest, a population-wide reduction in sugary beverage consumption could have public health benefit.
November 2022
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96 Reads
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5 Citations
Journal of School Health
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.
November 2022
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1,004 Reads
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1 Citation
Frontiers in Sleep
Sufficient sleep duration is associated with student health and wellbeing, but early secondary school start times limit students' sleep opportunity. Despite recommendations that all middle and high schools adopt a healthy school start time policy, one barrier to policy implementation is concerns about the impact on student participation in activities and employment. This study examined student extracurricular activity participation and employment before and after the implementation of healthy secondary school start times. Approximately 24,000 students/year (grades 3–11) completed three annual surveys (pre-change, post-change, follow-up) measuring sleep-wake patterns, extracurricular activity participation, and employment. Following the implementation of an earlier school start time, before-school activity participation decreased for elementary school students, but after-school participation was similar across years. Following the implementation of later school start times, there was a small decrease in after-school activity participation for middle and high school students (~3–4%). Equally important, middle and high school students reported significantly increased sleep duration with later start times, regardless of participation in before- or after-school activities and employment. Study findings support the recommendation for healthy school start time policies.
June 2022
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18 Reads
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5 Citations
Introduction Motor vehicle crashes (MVC) are the second leading cause of death for adolescents in the United States, with drowsy driving a major contributing factor. Early school start times have been identified as a significant factor that reduces adolescent sleep duration, which in turn contributes to drowsy driving and MVC. This paper examined the longitudinal impact of delaying secondary school start times on self‐reported student drowsy driving and teen MVC. Methods Secondary school students (10th and 11th grade, 51.7% female, 67.8% White) in the United States completed annual surveys 1 year before and 2 years after implementation of later school start times (70‐min delay, n range 1642–2452 per year), reporting frequency of drowsy driving (less than once/week vs. at least once/week). Teen (16–18 years) MVC data from the Colorado Department of Transportation for the 2 years before and 2 years after later start time implementation were compared for Arapahoe County (where start times changed) and neighboring Adams County and Douglas County (where start times did not change). Results With later start times, there was a significant drop in the percent of students who reported frequent drowsy driving (pre‐change: 32.6%, post‐change: 21.9%, follow‐up: 22.8%). Weekday teen MVC rates went down in Arapahoe County (p = .04) during the school year, while no change or increases in MVC rates were seen in neighboring counties. Conclusions Healthy school start times are important for adolescent health and safety, with study findings highlighting the downstream effects of increased sleep duration following a 70‐min delay in secondary school start times on adolescent drowsy driving and teen MVC rates.
January 2022
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40 Reads
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10 Citations
Sleep Medicine
Background Secondary school start times are associated with student sleep and daytime functioning; however, no study examining this association has included linked longitudinal data for both primary and secondary students. To understand the interplay between biology (i.e., normal developmental changes in sleep) and ecology (i.e., school start times), this study examined sleep and daytime functioning in elementary/primary and secondary school students over a three-year period that included changes to school start times. Methods Students (grades 3-10, n=6168) and parents (for student grades Kindergarten-2, n=2772) completed annual surveys before (pre-change) and for two-years after (post-change, follow-up) implementation of new school start times (elementary/primary: 60 minutes earlier, secondary: 50-80 minutes later). Participants were 48.9% female, 65.5% White, and 16.2% qualified for free/reduced lunch. Results With new school start times, significant changes were found for weekday wake times and sleep duration; elementary/primary students woke earlier (23 minutes) and obtained less sleep (14 minutes), while secondary students woke later (44 minutes) and obtained more sleep (31 minutes). Small changes in weekend sleep duration (<7 minutes) were found across levels. Secondary school students had significant improvements in daytime functioning post-change, due in part to changes in sleep duration. Minimal changes in elementary/primary students’ daytime functioning was found, despite shorter sleep duration. Conclusions School start times are a significant factor in weekday wake times for students across grade levels, while later bedtimes are more a factor of normal development. Later start times positively affected secondary students’ daytime functioning, with non-significant findings for earlier elementary/primary start times.
... Our recent parallel report indicated that healthy sleep and in-person education were also protective of depression and anxiety. 50 Together these studies highlight the importance of considering broad contributions to academic well-being in students in the post-COVID era. ...
January 2024
Sleep Health
... Zahlreiche Gesundheitsrisiken sind bei Erwachsenen mit dem Vorliegen von chronischem sozialen Jetlag assoziiert: Beispielsweise sind erhöhte Risiken für die Entstehung von psychischen Erkrankungen, Stoffwechselerkrankungen, Übergewicht und kardiovaskuläre Erkrankungen beschrieben [7][8][9]. Im Jugendalter ist das Vorliegen von sozialem Jetlag und Schlafmangel ebenfalls mit einer Reihe von Beeinträchtigungen verbunden: u. a. mit schlechteren schulischen Leistungen, verminderten kognitiven Fertigkeiten, dem Risiko für Übergewicht und Asthma [10,11]. Ebenso sind Depressionen und schwerwiegende affektive Symptome, [15]. ...
May 2023
Preventive Medicine
... 19 Finally, delaying school start times in middle and high school increases sleep time, academics outcomes, and quality of life. [20][21][22][23][24][25][26][27] While the pandemic is no longer central in our lives, it led to a proliferation of hybrid instructional models, with some families continuing in virtual instruction. 5,28 With this new status quo, the current study examined how sleep contributed to cognitive and academic function in adolescents across instructional approaches. ...
November 2022
Journal of School Health
... Compared with the same age groups in the USA (54.0%-62.6%) (Meltzer et al., 2022), 85% of Japanese students participated in extracurricular activities in this study. It is possible that, due to the overall high participation in extracurricular activities, these activities were not extracted as an associated factor for the incidence and persistence of social jetlag. ...
November 2022
Frontiers in Sleep
... Some studies suggest that earlier school start times predict less sleep for elementary students [8,11,12], while other researchers have found no association [13] or a more minor impact compared to middle and high school [8]. Further, later school start times for middle and high school students may confer additional benefits with respect to developmental outcomes, reduced daytime sleepiness, improved mood, fewer reports of morning tiredness, and fewer motor vehicle crashes [2,7,[10][11][12]14]. Thus, it is important to examine school start times, since they may impact sleep, as well as social and health outcomes. ...
June 2022
... With the onset of puberty, youth develop a greater tolerance for tiredness after extended awake-time (Taylor et al., 2005) and shift their circadian rhythm towards eveningness and later bedtimes (Randler et al., 2017). In combination with inflexible wake times constrained by school starting times on weekdays, these later bedtimes result in shorter sleep durations (Meltzer et al., 2022). Experiencing puberty at a younger age may therefore make youth particularly prone to later bedtimes and insufficient sleep patterns earlier in adolescence. ...
January 2022
Sleep Medicine
... Deception in relation to evidence can also lead to charges of contempt of court. However, the potential effectiveness of these tools is limited, as they require the detection of false evidence, and also as their operation is subject to judicial discretion [20,21]. Refusal of the courts to admit the tainted evidence for determination is the most they can do to counter that problem. ...
January 2022
Sleep Health
... Later school start times also have the potential to positively impact other members in the family. For example, a recent study showed that parents' sleep-wake patterns also changed with the implementation of later middle and high school start times [108]. Specifically, later school start times were associated with greater number of parents obtaining sufficient sleep, as well as greater sleep quality of parents of adolescents. ...
October 2021
... In our study, despite a marked increase in TST during the weekends without competition, this increment still did not meet the minimum recommendation of 8 h. Typically, non-athlete adolescents use the weekend to extend their TST to durations that align with these recommendations [35]. Thus, whether the weekend adjustments observed in our study are practically significant remains uncertain (i.e., if these small increments are still helpful in minimizing the effects of sleep debt from weekdays). ...
August 2021
... Late sleep onset times associated with mid-to-late adolescence are partly driven by a puberty-related slowing of homeostatic sleep pressure buildup across waking [7], a delay shift of the central circadian timing system [8,9], and potentially a robust circadian-driven wake maintenance zone around the time of the dim light melatonin onset (DLMO) [10]. Late school-night sleep onset times with early rise times on school-day mornings make it difficult for adolescents to obtain sufficient sleep [11,12]. Chronic partial sleep deprivation is especially common for adolescents who endorse an evening chronotype [13]. ...
August 2021
Sleep