Chronobiological changes due to school closures during the COVID-19 pandemic among adolescents in the DOrtmund Nutritional and Anthropometric Longitudinally Designed cohort study.

Due to the lockdown of schools as one of the COVID-19 control measures, adolescents have had the opportunity to re-organise their daily lives; e.g. some of them have adapted their bedtimes to the new situation during the lockdown in favour of their own chronotype. Hence, we investigated differences in chronobiological characteristics (e.g., the midpoint of sleep, sleep duration or social jetlag (SJL); i.e., a discrepancy between biological and social timing) before and during the pandemic lockdown to examine potential changes. We asked participants from the ongoing open cohort Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study to fill out the Munich Chronotype Questionnaire during the COVID-19 lockdown and received the information of participants (n = 66) during the pandemic. A reference group matched for age, season, and sex was randomly selected from the DONALD study to assess participants' chronobiological characteristics prior to (n = 132) the pandemic. Analyses of covariance were applied to examine differences between the two groups reflecting the situation before and during the COVID-19 pandemic. Participants were aged 9-18 years (52% males). In the current examination, average sleep duration across the week was higher among adolescents during the pandemic (ß = 00:30; p = 0.0006) and social jetlag was significantly lower (ß = -00:39; p < 0.0001). CONCLUSION: Our results showed that the COVID-19 lockdown enabled adolescents to adapt their sleeping habits according to their naturally late chronotype, which led to a significant reduction in SJL. These observations are likely to be explained by the effect of school closure. WHAT IS KNOWN: • Under 'normal conditions' without pandemic lockdowns, adolescents accumulate a lack of sleep due to social obligations such as school starts, resulting in social jetlag. • A late chronotype or exposure to social jetlag is a known risk factor for the development of chronic diseases. WHAT IS NEW: • The COVID-19 lockdown represents a 'natural experiment' that enables adolescents to adhere to their internal biological clock. Without the usual social obligations, social jetlag can be significantly reduced.

Weight status of working adults: The effects of eating misalignment, chronotype, and eating jetlag during mandatory confinement.

This study aimed to examine the association between chronotype, eating jetlag, and eating misalignment with weight status among Malaysian adults during the COVID-19 restriction. This online cross-sectional study included 175 working adults recruited from March to July 2020. The chronotype was assessed using Morningness Eveningness Questionnaire (MEQ) while eating jetlag and mealtime variability were measured using Chrononutrition Profile Questionnaire (CPQ). Multiple linear regression demonstrated that lower breakfast frequency (ß = -0.258, p = .002) and longer eating duration (ß = 0.393, p < .001) were associated with later first eating events on workfree days. Both intermediate (ß = 0.543, p < .001) and evening chronotypes (ß = 0.523, p = .001) tend to eat their first meals later compared to morning person. Similar patterns were observed for overall eating jetlaggers in which lower breakfast frequency (ß = -0.022, p = .011), longer eating duration (ß = 0.293, p < .001), intermediate chronotype (ß = 0.512, p < .001), and evening chronotype (ß = 0.495, p = .003) were associated with eating later meals on workfree days. Additionally, higher BMI was also associated with eating later meals on workfree days (ß = 0.181, p = .025). During movement restriction, discrepancies of mealtimes during work and workfree days offer new insight into modern eating habits that can influence weight status and general eating habits such as breakfast skipping and total daily eating duration. Population meal timing variability was affected during movement restrictions, and it was closely related to weight status.

Association of smartphone use with abnormal social jetlag among adolescents in Korea before and after COVID-19.

PURPOSE: This study aimed to use social jetlag to determine how smartphone overuse by adolescents before and after the COVID-19 pandemic might be associated with their circadian rhythm. METHODS: We used 2017 and 2020 Korea Youth Risk Behavior web-based Survey data and conducted a survey analysis on 100,976 adolescents. The dependent variable was abnormal social jetlag. Based on the times recorded by the survey, we calculated the weekday midpoint and weekend sleep time. The main independent variable was smartphone usage time (<2h/day, 2-3.9 h/day, 4-5.9 h/day, and ≥ 6 h/day). Multiple logistic regression and relative excess risk due to interaction (RERI) were performed. RESULTS: Abnormal social jetlag was most prevalent in male and female adolescents who used smartphones ≥ 6 h/day (adjusted odds ratio [AOR] = 2.60, 95 % confidence interval [CI] = 2.47-2.74). The longer the smartphone usage time, the higher the association with abnormal social jetlag. This association was more prominent in female adolescents. The additive interaction between longer smartphone usage time and post-COVID-19 year was statistically significant (total: RERI = 0.92, 95 % CI = 0.90-0.95; males: RERI = 0.83, 95 % CI = 0.80-0.87; females: RERI = 1.13, 95 % CI = 1.08-1.18). CONCLUSION: Our results clearly indicated that increased smartphone usage time tended to result in greater social jetlag, an association that was more pronounced in female. Moreover, the COVID-19 pandemic significantly strengthened this relationship. Further research is needed regarding the proper use of smartphones to ensure good sleep-in adolescents after the COVID-19 pandemic.

The association of chronotype and social jet lag with body composition in German students: The role of physical activity behaviour and the impact of the pandemic lockdown.

Young adults with a later chronotype are vulnerable for a discrepancy in sleep rhythm between work- and free days, called social jet lag (SJL). This study analysed (i) chronotype/SJL association with visceral fat/skeletal muscle mass, (ii) the attribution to physical activity behaviour, and (iii) chronotype-specific changes in physical activity behaviour in young adults during the Covid-19 pandemic lockdown. Chronotype and SJL were derived from the Munich-Chrono-Type-Questionnaire in 320 German students (age 18-25 years) from September 2019 to January 2020, 156 of these participated in an online follow-up survey in June 2020. Body composition was assessed by bioimpedance analysis at baseline. Multivariable linear regression analyses were used to relate chronotype/SJL to body composition; the contribution of self-reported physical activity was tested by mediation analysis. At baseline, a later chronotype and a larger SJL were associated with a higher visceral fat mass (P<0.05), this relation was notably mediated by the attention to physical activity (P<0.05). Chronotype (P = 0.02) but not SJL (P = 0.87) was inversely associated with skeletal muscle mass. During the pandemic lockdown, chronotype hardly changed, but SJL was reduced. Timing and physical activity behaviour remained in most participants and changes were unrelated to chronotype (all P>0.07). A later chronotype/higher SJL may increase the risk of a higher visceral fat mass even in this relatively healthy sample, which may be partly due to their physical activity behaviour. Despite a reduction in SJL during the pandemic lockdown, later chronotypes did not change their physical activity behaviour more than earlier chronotypes.

Prediction of Long COVID Based on Severity of Initial COVID-19 Infection: Differences in predictive feature sets between hospitalized versus non-hospitalized index infections (preprint)

Long COVID is recognized as a significant consequence of SARS-COV2 infection. While the pathogenesis of Long COVID is still a subject of extensive investigation, there is considerable potential benefit in being able to predict which patients will develop Long COVID. We hypothesize that there would be distinct differences in the prediction of Long COVID based on the severity of the index infection, and use whether the index infection required hospitalization or not as a proxy for developing predictive models. We divide a large population of COVID patients drawn from the United States National Institutes of Health (NIH) National COVID Cohort Collaborative (N3C) Data Enclave Repository into two cohorts based on the severity of their initial COVID-19 illness and correspondingly trained two machine learning models: the Long COVID after Severe Disease Model (LCaSDM) and the Long COVID after Mild Disease Model (LCaMDM). The resulting models performed well on internal validation/testing, with a F1 score of 0.94 for the LCaSDM and 0.82 for the LCaMDM. There were distinct differences in the top 10 features used by each model, possibly reflecting the differences in type and amount of pathophysiological data between the hospitalized and non-hospitalized patients and/or reflecting different pathophysiological trajectories in the development of Long COVID. Of particular interest was the importance of Plant Hardiness Zone in the feature set for the LCaMDM, which may point to a role of climate and/or sunlight in the progression to Long COVID. Future work will involve a more detailed investigation of the potential role of climate and sunlight, as well as refinement of the predictive models as Long COVID becomes increasingly parsed into distinct clinical phenotypes.

Effects of long-haul transmeridian travel on physiological, sleep, perceptual and mood markers in Olympic team support staff.

The objective of this study was to holistically examine the impact of long-haul transmeridian travel (LHTT) on perceptual, mood, sleep and physiological markers in Olympic team support staff travelling to Japan for the 2020 Summer Olympic Games. An observational descriptive study design was used. Nine support staff members of the Irish Olympic team (2 M/7 F; age 34.3 ± 8.3 y (mean ±SD)) embarked on a long-haul (LH) eastward flight across eight time-zones from Ireland to Japan (approx. 24 h total travel time), to work at the Irish Team's 2020 Summer pre-Olympic Games camp, postponed to July 2021 due to Covid-19 pandemic. Perceived jet lag and travel fatigue symptoms, mood states and salivary markers for circadian rhythm and stress were assessed in the morning and evening during the week prior to travel as baseline (BL) measures and on days 1 to 8 (C1-C8) and day 15 (C15) post-travel. Night-time sleep (duration and quality) was monitored via actigraphy monitors and self-report sleep diaries. Participants perceived themselves to be significantly jet lagged for six days post-travel (p < .05). Morning sCort decreased by 66% on C1 and remained significantly lower than BL until C6 (p ≤ .03). On arrival participants perceived sleep to be worse than BL on arrival (C1, C2, C4, C5; p ≤ .04), with significantly shorter sleep duration (C2, C3, C6; p ≤ .01) and lower sleep efficiency (C2, C6; p ≤ .04) recorded by actigraphy, all normalizing by C7. Negative changes in mood states were evident in the evening time following LHTT, with significant elevations in confusion (C2, C3, p ≤ .02), fatigue (C2, C3; p ≤ .03) and depression (C3, C7; p < .05) and reduction in vigour (C2, C6, C7; p < .05). Following LHTT in an eastward direction across eight time-zones, it took seven days for perceived jet lag, physiological markers for circadian rhythm and sleep to normalize in Olympic team support staff. Despite alleviation of jet lag and fatigue and return of sleep to normal by C15, vigor remained low, indicating a "submerged" mood profile in these Olympic team support staff. These findings highlight the need to put strategies in place before and after LHTT for the Olympic Games to assist Olympic team support staff to maximize sleep, minimize stress and assist with expediating recovery from jet lag and travel fatigue, allowing them to perform optimally in supporting Olympic athletes in their final preparations for the Games.

COVID-19-lockdown delayed sleep timing in Tyrolean teachers.

Delayed school start times improve students' sleep, but little is known about its impact on teachers. The Austrian COVID-19 lockdown, enabling teachers to choose their working hours, created the unique opportunity to test the impact of a forced home office on Tyrolean teachers' sleep. From April to May 2020, a cross-sectional and complete online survey was implemented with 2,314 Tyrolean teachers participating. Bedtimes and wake times on workdays and on weekends were measured before the lockdown (retrospectively) and during the lockdown. Additional variables were calculated: time spent in bed on workdays/weekends, social jetlag, and sleep loss. During the lockdown, as compared to the period before it, the teachers reported later bedtimes and rise times, longer sleep duration on workdays, decreased workday sleep loss, and reduced social jetlag. These effects occurred predominantly due to a delay in rise times on workdays and were enhanced in younger teachers. Changing to a home office during lockdown induced a robust drift towards later hours on workdays, indicating that teachers benefit from delayed school start times by aligning their workday sleep habits to their biological sleep needs. In conclusion, not only adolescent students but also teachers benefit from a delayed school start.

Circadian misalignment is associated with Covid-19 infection.

BACKGROUND: Circadian system contributes to the regulation of inflammatory processes, but the role of circadian misalignment as a risk factor for contracting Covid-19 has up to now been poorly studied. The aim of this study was to explore the relationship between circadian misalignment (chronic disturbance of the circadian system) and the risk of Covid-19 infection in a population of subjects suspected of contact or infection with SARS-CoV-2. METHODS: Cross-sectional single-center study conducted during a period without lockdown in winter 2021. Recruitment took place in a Covid-19 outpatient testing center. Subjects between 18 and 45 years old were included whether they were symptomatic or not, healthcare workers or not, in contact with a Covid-19 case or not. To determine social jetlag, a proxy of circadian misalignment, they were asked about their usual sleep-wake behaviors. Usual sleep duration and sleep-wake timing were explored on workdays and free days. Social jetlag was defined as at least 2 h shift of circadian alignment (defined as the difference between mid-sleep on workdays and mid-sleep on free days, mid-sleep as the median between bedtime and rise time). RESULTS: One thousand fourteen subjects were included (sampling rate: 10.8%, 39% men, mean age 28 ± 8) with 56 subjects positive for Covid-19 (positivity rate: 5.5%). Usual mean sleep duration was equivalent in both groups (7h47 versus 7h49, p = 0.733). Social jetlag greater than 2 h comprised 33.3% of subjects in the Covid-19 group versus 20.6% in the control group (p = 0.026). After adjustment on age, gender, BMI and work schedules, subjects presenting with social jetlag greater than 2 h had a 2.07-fold higher likelihood to test positive than subjects who had identical sleep-wake timing on workdays and free days (OR = 2.07, 95%CI = [1.12-3.80], p = 0.024). CONCLUSION: Circadian misalignment not only is present in subjects infected by Covid-19 but could also be responsible for a higher likelihood of being infected. The chronobiological impact on the immune system or a higher likelihood of being exposed to social contacts during nocturnal activities could explain our findings, which need to be confirmed in a future large cohort study. Regular sleep-wake timing could ultimately become a target for preventing Covid-19 infection.

Changes in sleep behavior, sleep problems, and psychological distress/health-related quality of life of young Japanese individuals before and during the COVID-19 pandemic.

Social restrictions during the coronavirus disease (COVID-19) pandemic have impacted sleep behavior and sleep problems, and their related daytime functioning in young adults. However, no studies have examined such changes in young individuals from countries with mild infection intensity and social restrictions. Therefore, we focused on sleep behaviors and sleep issues in young people in Japan. This study was conducted before and after the pandemic (October 2019 and May 2020, respectively). In total, 2,222 (1,371 students and 851 workers) individuals participated and completed anonymous Web-based questionnaires concerning demographic characteristics, sleep behaviors, sleep problems using the Japanese version of the Epworth Sleepiness Scale (JESS) and the Athens Insomnia Scale (AIS-J), psychological distress using the Japanese version of the Kessler Psychological Distress Scale, and health-related quality of life (HRQoL) evaluated with the Short Form-8 (SF-8). A significantly delayed sleep phase was observed in the second survey compared to the first (p < .001) and was more pronounced in students than in workers (p < .001). The total sleep time, social jetlag degree, and JESS, AIS-J, and SF-8 scores were significantly improved after the pandemic (p < .001, p < .001, p < .001, p < .001, p < .05, and p < .001, respectively). Careful monitoring of whether these modest changes can lead to adjustment concerns is needed.

The Spatiotemporal Interaction Effect of COVID-19 Transmission in the United States (preprint)

Background: Human mobility among geographic units is a possible cause of the widespread transmission of COVID-19 across regions. Due to the pressure of epidemic control and economic recovery, the states of the United States have adopted different policies for mobility limitations. Assessing the impact of these policies on the spatiotemporal interaction of COVID-19 transmission among counties in each state is critical to formulating the epidemic policies.Methods: The study utilized Moran’s I index and K-means clustering to investigate the time-varying spatial autocorrelation effect of 49 states (except the District of Colombia) with the daily new cases at the county level from Jan 22, 2020, to August 20, 2020. Based on the dynamic spatial lag model (SLM) and the SIR model with unreported infection rate (SIRu), the integrated SLM-SIRu model was constructed to estimate the inter-county spatiotemporal interaction coefficient of daily new cases in each state, which was further explored by Pearson correlation and stepwise OLS regression with socioeconomic factors.Results: The K-means clustering divided the time-varying spatial autocorrelation curves of 49 states into four types: continuous increasing, fluctuating increasing, weak positive, and weak negative. The Pearson correlation analysis showed that the spatiotemporal interaction coefficients in each state estimated by SLM-SIRu were significantly positively correlated with median age, population density, and the proportion of international immigrants and the highly educated population, but negatively correlated with the birth rate. The voting rate for Donald Trump in the 2016 U.S. presidential election showed a weak negative correlation. Further stepwise OLS regression retained only three positive correlated variables: poverty rate, population density, and the highly educated population proportion.Interpretation: This result suggests that various state policies in the U.S. have imposed different impacts on COVID-19 transmission among counties. All states should provide more protection and support for the low-income population, high-density populated states need to strengthen regional mobility restrictions, and the highly educated population should reduce unnecessary regional movement and strengthen self-protection. 

COVID-19-mandated social restrictions unveil the impact of social time pressure on sleep and body clock.

In humans, sleep regulation is tightly linked to social times that assign local time to events, such as school, work, or meals. The impact of these social times, collectively-social time pressure, on sleep has been studied epidemiologically via quantification of the discrepancy between sleep times on workdays and those on work-free days. This discrepancy is known as the social jetlag (SJL). COVID-19-mandated social restrictions (SR) constituted a global intervention by affecting social times worldwide. We launched a Global Chrono Corona Survey (GCCS) that queried sleep-wake times before and during SR (preSR and inSR). 11,431 adults from 40 countries responded between April 4 and May 6, 2020. The final sample consisted of 7517 respondents (68.2% females), who had been 32.7 ± 9.1 (mean ± sd) days under SR. SR led to robust changes: mid-sleep time on workdays and free days was delayed by 50 and 22 min, respectively; sleep duration increased on workdays by 26 min but shortened by 9 min on free days; SJL decreased by ~ 30 min. On workdays inSR, sleep-wake times in most people approached those of their preSR free days. Changes in sleep duration and SJL correlated with inSR-use of alarm clocks and were larger in young adults. The data indicate a massive sleep deficit under pre-pandemic social time pressure, provide insights to the actual sleep need of different age-groups and suggest that tolerable SJL is about 20 min. Relaxed social time pressure promotes more sleep, smaller SJL and reduced use of alarm clocks.

Local Economic Zones For Economic Development (preprint)

All countries, especially facing a posit COVID-19 disrupted world, are keen to promote economic development that will be resilient to future external shocks. Over the years many different forms of “development structure” have been attempted including Export Processing Zones, Special Economic Zones, Free Trade Zones, High Technology Zones, clusters and so and so forth. Whilst some of these have been very successful in themselves, others have not; and there is evidence that even if the zone is successful itself, there is no inevitable consequence that business in the nearby locality will benefit.This contribution establishes a “Post Pandemic” localised economic development framework based upon “Local Economic Zones”, where anchors drive local activity whilst being themselves strengthened to be competitive on a regional, pan regional and global level.The methodology focuses on developing and connecting what already exists, gap filling by (i) providing access to technology, finance and skills development through a gateway or anchor institution (possibly an “entrepreneurial university” that is local in character, but global in outlook and (ii) access to affordable working capital via a specific community currency and gateways to banks and capital markets through building accurate and accessible business histories and associated credit information.

COVID-19-related mobility reduction: heterogenous effects on sleep and physical activity rhythms.

STUDY OBJECTIVES: Mobility restrictions imposed to suppress transmission of COVID-19 can alter physical activity (PA) and sleep patterns that are important for health and well-being. Characterization of response heterogeneity and their underlying associations may assist in stratifying the health impact of the pandemic. METHODS: We obtained wearable data covering baseline, incremental mobility restriction, and lockdown periods from 1,824 city-dwelling, working adults aged 21-40 years, incorporating 206,381 nights of sleep and 334,038 days of PA. Distinct rest-activity rhythm (RAR) profiles were identified using k-means clustering, indicating participants' temporal distribution of step counts over the day. Hierarchical clustering of the proportion of days spent in each of these RAR profiles revealed four groups who expressed different mixtures of RAR profiles before and during the lockdown. RESULTS: Time in bed increased by 20 min during the lockdown without loss of sleep efficiency, while social jetlag measures decreased by 15 min. Resting heart rate declined by ~2 bpm. PA dropped an average of 42%. Four groups with different compositions of RAR profiles were found. Three were better able to maintain PA and weekday/weekend differentiation during lockdown. The least active group comprising ~51% of the sample, were younger and predominantly singles. Habitually less active already, this group showed the greatest reduction in PA during lockdown with little weekday/weekend differences. CONCLUSION: In the early aftermath of COVID-19 mobility restriction, PA appears to be more severely affected than sleep. RAR evaluation uncovered heterogeneity of responses to lockdown that could associate with different outcomes should the resolution of COVID-19 be protracted.

Effects of lockdown on human sleep and chronotype during the COVID-19 pandemic.

The COVID-19 pandemic [1] resulted in many countries imposing a lockdown, which in turn reduces sunlight exposure and alters daily social schedules. Since these are the main entrainment factors for biological rhythms [2], we hypothesized that the lockdown may have affected sleep and circadian rhythms. We indeed show that participants slept longer and later during lockdown weekdays, and exhibited lower levels of social jetlag. While this may seem to be an overall improvement of sleep conditions, chronotype was also delayed under the lockdown. This signature of a weaker light-dark cycle should be monitored attentively since it may progressively cause disruptive effects on sleep and circadian rhythms, affecting human performance and health [3].