The majority of Icelandic adolescents did not get the recommended number of hours of sleep, especially on SchD. While TST increased on NSchD, many participants still did not achieve the recommendations. These findings provide information on the sleep patterns of adolescents and may serve as reference for development of policies and interventions to promote better sleep practices.

ObjectiveFew studies have explored the potential interrelated associations of screen time and physical activity with mental health in youth, particularly using objective methods. We examined cross-sectional associations of these variables among Icelandic adolescents, using objective and subjective measurements of physical activity.MethodsData were collected in the spring of 2015 from 315 tenth grade students (mean age 15.8 years) in six elementary schools in metropolitan Reykjavík, Iceland. Participants reported, via questionnaire, on demographics, weekly frequency of vigorous physical activity, daily hours of screen time and mental health status (symptoms of depression, anxiety and somatic complaints, self-esteem and life satisfaction). Total physical activity was measured over one week with wrist-worn accelerometers. Body composition was determined by DXA-scanning. Poisson regression analysis was used to explore independent and interactive associations of screen time and physical activity with mental health variables, adjusting for gender, body fat percentage and maternal education.ResultsLess screen time (below the group median of 5.3 h/day) and more frequent vigorous physical activity (≥4x/week) were each associated with reporting fewer symptoms of depression, anxiety, low self-esteem, and life dissatisfaction. No significant associations were observed between objectively measured physical activity and mental health outcomes. Interactive regression analysis showed that the group reporting both less screen time and more frequent vigorous physical activity had the lowest risk of reporting symptoms of depression, anxiety, low self-esteem, and life dissatisfaction.ConclusionsReports of less screen time and more frequent vigorous physical activity were associated with lower risk of reporting mental health problems among Icelandic adolescents. Those who reported a combination of engaging in less screen time and more frequent vigorous physical activity had the lowest risk, suggesting a synergistic relationship between the two behaviors on mental health outcomes. Our results support guiding youth towards more active and less sedentary/screen-based lifestyle.

Objectives: Emerging evidence suggests that inconsistent sleep may affect physical and psychological health. Thus, it is important to identify modifiable determinants of sleep variability. Screen time and physical activity are both thought to affect sleep, but studies of their relationship to sleep variability using objective measures are lacking. We examined cross-sectional associations between these variables in mid-teen adolescents using objectively measured sleep and activity.Methods: Wrist-worn accelerometers were used to measure one week of sleep and activity in 315 tenth grade students (mean age 15.8y) from six Reykjavik compulsory schools. Participants reported their daily hours of screen time. Regression analysis was used to explore associations of screen time and physical activity with variability in duration, quality, and timing of sleep, adjusting for DXA-measured body fat percentage, parental education, and physical activity or screen time.

Objective COVID-19 has affected people’s health in various ways. University students are a particularly sensitive group for mental and physical health issues. The aim of this study was to assess and compare the mental and physical health of male and female first-year university students during and before COVID-19. Method Total of 115 first-year university students (54% male) answered questions about mental and physical health. The students were asked to estimate their physical activity, sedentary behavior, loneliness, stress, and sleep quality during COVID-19 opposed to before the pandemic. Result Males had fewer symptoms of anxiety and depression, and their self-esteem was higher than females (p<0.05). Over 50% of both genders estimated their mental health to be worse than before COVID-19. Larger proportion of males (69%) compared to females (38%) estimated that their physical health had worsened than before the pandemic. Larger proportion of females (38%) than males (14%) experience increased loneliness and stress (68% vs. 48%). Over 70% of both genders estimated increased sedentary behavior than before the pandemic, and larger proportion of males (76%), compared to females (56%), estimated that they were less physically active than before COVID-19. About 50% of participants estimated their sleep quality was worse than before COVID-19. Conclusion University students estimated their mental and physical health to have deteriorated during the pandemic. Therefore, it is important that the school and healthcare systems assist students in unwinding these negative health and lifestyle changes that have accompanied the pandemic.

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24Background 25 Sleep and physical activity are modifiable behaviors that play an important role in preventing 26 overweight, obesity, and metabolic health problems. Studies of the association between 27 concurrent objective measures of sleep, physical activity, and metabolic risk factors among 28 adolescents are limited. 29 Objective 30The aim of the study was to examine the association between metabolic risk factors and 31 objectively measured school day physical activity and sleep duration, quality, onset, and 32 variability in adolescents. 34 We measured one school week of free-living sleep and physical activity with wrist actigraphy 35 in 252 adolescents (146 girls), aged 15.8±0.3 years. Metabolic risk factors included body mass 36 index, waist circumference, total body and trunk fat percentage, resting blood pressure, and 37 fasting glucose and insulin levels. Multiple linear regression adjusted for sex, parental 38 education, and day length was used to assess associations between metabolic risk factors and 39 sleep and activity parameters. 33 Materials and Methods40 Results 41On average, participants went to bed at 00:22±0.88 hours and slept 6.2±0.7 hours/night, with 42 0.83±0.36 hours of awakenings/night. However, night-to-night variability in sleep duration 43 (0.87±0.57 hours) and bedtime (0.79±0.58 hours) was considerable. Neither average sleep 44 duration nor mean bedtime was associated with any metabolic risk factors. However, greater 45 night-to-night variability in sleep duration was associated with higher total body (β=1.9±0.9 3 46 %/h, p=0.03) and trunk fat percentage (β=1.6±0.7 %/h, p=0.02), poorer sleep quality (more 47 hours of awakening) was associated with higher systolic blood pressure (β=4.9±2.2 mmHg/h, 48 p=0.03), and less physical activity was associated with higher trunk fat percentage (p=0.04) and 49 insulin levels (p=0.01). 50 Conclusion 51Greater nightly variation in sleep, lower sleep quality, and less physical activity was associated 52 with a less favorable metabolic profile in adolescents. These findings support the idea that, 53 along with an adequate amount of sleep and physical activity, a regular sleep schedule is 54 important to the metabolic health of adolescents. 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 4 70 71The prevalence of overweight in the world has nearly tripled from 1975-2016, with over 72 39% of adults and 18% of children and adolescents being overweight or obese [1]. Greater total 73 body and central adiposity is associated with increased risk of cardio-metabolic comorbidities, 74 such as hypertension and diabetes [2, 3]. Prevalence of metabolic syndrome is high among 75 obese children and adolescents and increases with higher central obesity [4]. Along with diet, 76 sleep and physical activity have been identified as important modifiable risk factors implicated 77 in the development of overweight, obesity, and metabolic health problems [5]. 78 The importance of adequate sleep for health and daily functioning in adolescents is well 79 established [...

Background Sleep and physical activity are modifiable behaviors that play an important role in preventing overweight, obesity, and metabolic health problems. Studies of the association between concurrent objective measures of sleep, physical activity, and metabolic risk factors among adolescents are limited. Objective The aim of the study was to examine the association between metabolic risk factors and objectively measured school day physical activity and sleep duration, quality, onset, and variability in adolescents. Materials and methods We measured one school week of free-living sleep and physical activity with wrist actigraphy in 252 adolescents (146 girls), aged 15.8±0.3 years. Metabolic risk factors included body mass index, waist circumference, total body and trunk fat percentage, resting blood pressure, and fasting glucose and insulin levels. Multiple linear regression adjusted for sex, parental education, and day length was used to assess associations between metabolic risk factors and sleep and activity parameters. Results On average, participants went to bed at 00:22±0.88 hours and slept 6.2±0.7 hours/night, with 0.83±0.36 hours of awakenings/night. However, night-tonight variability in sleep duration was considerable (mean ± interquartile range) 0.75±0.55 hours) and bedtime (0.64 ±0.53 hours) respectively. Neither average sleep duration nor mean bedtime was associated with any metabolic risk factors. However, greater night-tonight variability in sleep

Introduction: Sleep is often quantified using self-report or actigraphy. Self-report is practical and less technically challenging, but prone to bias. We sought to determine whether these methods have comparable sensitivity to measure longitudinal changes in adolescent bedtimes. Methods: We measured one week of free-living sleep with wrist actigraphy and usual bedtime on school nights and non-school nights with self-report questionnaire in 144 students at 15 y and 17 y. Results: Self-reported and actigraphy-measured bedtimes were correlated with one another at 15 y and 17 y (p < .001), but reported bedtime was consistently earlier (>30 minutes, p < .001) and with wide inter-method confidence intervals (> ±106 minutes). Mean inter-method discrepancy did not differ on school nights at 15 y and 17 y but was greater at 17 y on non-school nights (p = .002). Inter-method discrepancy at 15 y was not correlated to that at 17 y. Mean change in self-reported school night bedtime from 15 y to 17 y did not differ from that by actigraphy, but self-reported bedtime changed less on non-school nights (p = .002). Two-year changes in self-reported bedtime did not correlate with changes measured by actigraphy. Conclusions: Although methods were correlated, consistently earlier self-reported bedtime suggests report-bias. More varied non-school night bedtimes challenge the accuracy of self-report and actigraphy, reducing sensitivity to change. On school nights, the methods did not differ in group-level sensitivity to changes in bedtime. However, lack of correlation between bedtime changes by each method suggests sensitivity to individual-level change was different. Methodological differences in sensitivity to individual- and group-level change should be considered in longitudinal studies of adolescent sleep patterns.