Combined Effect of Outdoor Time and Other Modifiable Factors on Myopia Incidence Among Children and Adolescents - 9 PLADs, China, 2020

What is already known about this topic?

Myopia has been identified as a significant emerging challenge and policy priority among children and adolescents in China by the Ministry of Education and seven other departments. Limited research has been conducted to investigate the collective impact of outdoor time and other modifiable factors on the incidence of myopia.

What is added by this report?

This study provides support for the protective effect of combining increased outdoor time with other prevention strategies in reducing the incidence of myopia. The results indicate the presence of a dose-response relationship.

What are the implications for public health practice?

To effectively prevent myopia, it is important to implement comprehensive interventions that encompass various aspects such as outdoor time, eye-use habits, eye-use environments, and lifestyle modifications.

Compensatory Interactions between Corneal and Internal Astigmatism despite Lifestyle Changes

This study explores whether children's refractive errors and visual behaviors reverted to pre-COVID-19 levels a year after normal schooling resumed in Hong Kong as well as the impact of corneal and internal astigmatism on refractive astigmatism development. Vision survey data and questionnaire results collected in 2022 (n = 119) and 2020 (n = 173) were compared. Cross-sectional data showed similar proportions of astigmatism (cylindrical power ≥ 0.75 D) in the 2020 (49.1%) and 2022 cohorts (55.5%). Despite a 0.28 D increase in corneal astigmatism, a compensatory 0.24 D increase in internal astigmatism of opposite direction kept refractive astigmatism relatively stable. The questionnaire data showed that children spent an additional 0.5 h/day outdoors on weekends post-resumption of normal schooling but engaged in more near-work activities, especially non-screen near-work, by approximately 1 h/day on both weekdays and weekends. These findings were supported by longitudinal data from 72 children who participated in both surveys. This study highlights the significant role of corneal and internal astigmatism in refractive astigmatism changes. Despite the return to in-person classes, children's total near-work time increased and astigmatism remained high. These findings underscore the need for comprehensive strategies to reduce the high environmental risks for refractive error development in children.

Predicting the child who will become myopic - can we prevent onset?

Myopia has become a global epidemic with significant public health impacts. Identifying the child at risk of developing myopia, i.e. the pre-myopic child and implementing strategies to prevent the onset of myopia, could significantly reduce the burden of myopia on an individual and society. This paper is a review of publications that have identified ocular characteristics of children at risk of future myopia development including a lower than age normal amount of hyperopia and accelerated axial length elongation. Risk factors associated with increased risk of myopia development such as education exposure and reduced outdoor time, and strategies that could be implemented to prevent myopia onset in children are also explored. The strong causal role of education and outdoor time on myopia development suggests that lifestyle modifications could be implemented as preventative measures to at-risk children and may significantly impact the myopia epidemic by preventing or delaying myopia onset and its associated ocular health consequences.

Indoor and outdoor human behavior and myopia: an objective and dynamic study

Significance

Myopia holds significant public health concern given its social, ocular disease and economic burdens. Although environmental factors are primarily to blame for the rapid rise in prevalence, key risk factors remain unresolved.

Purpose

The aim of this study was to objectively characterize, using a wearable technology, the temporal indoor and outdoor behavioral patterns and associated environmental lighting characteristics of young myopic and nonmyopic University students.

Methods

Participants were recruited to continuously wear an Actiwatch for 3 weeks, during either or both academic and non-academic periods. The device allows continuous recording of activity and incident light. Recorded illuminance levels were used as a proxy for outdoors (>1,000 lux), with the dynamics (interval frequency and duration) of indoor and outdoor activities, as well as lighting characteristics derived. In addition, participant input regarding near work was obtained daily. Participants were classified by both myopia and axial length status (based on collected refractive error and biometry data) for the purpose of data analysis.

Result

A total of 55 students, aged 18 to 25 years of age, participated. Overall, the dosing of indoor and outdoor activities was similar across participants, regardless of myopia status, during the academic period. Nonetheless, an apparent difference in the timing of outdoor activities was noted with myopes going outdoors later in the day, particularly during the weekend (p = 0.03). While a trend was observed between increased lighting levels experienced outdoors and shorter axial lengths, there was no significant relationship with myopia status. Noteworthy, participants generally significantly overestimated time spent outdoors, compared to Actiwatch-derived estimates of the same.

Conclusion

While the findings from this cohort of young adult students did not reveal substantial myopia-related differences in behavior, the power of a more objective and dynamic approach to quantifying behavior cannot be understated, providing argument for general adoption of wearable technologies in future clinical myopia studies.

Outdoor Time, Space, and Restrictions Imposed on Children's Play in Australian Early Childhood Education and Care Settings during the COVID Pandemic: A Cross-Sectional Survey from Educators' Perspective

The study aimed to investigate the impact of COVID-19 restrictions on children's access to the outdoors in early childhood education and care (ECEC) settings. An online survey comprised of a standardised scale and questions used in previous related studies was completed by 143 early childhood educators across Australia. Participants were asked to report children's time spent outdoors, access to outdoor space, and restrictions imposed on children's play during the pandemic compared to the pre-pandemic period. The survey responses were imported into SPSS for descriptive, correlation, and ordinal regression analyses. We examined the relationship between children's outdoor time, space, restrictions imposed on children's play, and educators' characteristics, such as qualifications, professional development, and tolerance of risk or staff-child ratios during the pandemic in Australia. Most educators reported that children's outdoor time and access to outdoor space remained the same compared to before the pandemic, while imposed restrictions on children's outdoor play increased. The results of ordinal regressions indicated that educators with a higher tolerance of risk were less likely to impose additional restrictions on children's outdoor play. The findings contribute to the understanding of how educators' tolerance of risk influences children's outdoor play opportunities and provide directions for future risk-reframing interventions.

The outdoor environment affects retinal and choroidal thickness

PURPOSE

Accumulating evidence suggests that time outdoors is protective against myopia development and that the choroid may be involved in this effect. The goal of this study was to examine the effect of 2 h of time outdoors in sunlight on retinal and choroidal thickness in adults.

METHODS

Twenty adults, ages 23-46 years, each participated in three experimental sessions on different days, consisting of 2 h of exposure to (1) indoor illumination (350 lux), (2) darkness (<0.1 lux) or (3) outdoor environment (6000-50,000 lux). Spectral-domain optical coherence tomography (SD-OCT) imaging was conducted at baseline, after 1 and 2 h of exposure, and after 1 and 2 h of follow-up. Choroidal, total retinal, photoreceptor outer segment + retinal pigment epithelium (RPE) and photoreceptor inner segment thicknesses were determined.

RESULTS

At 2 h, the choroid was significantly thinner during the outdoor compared with the indoor and dark conditions (p < 0.01) but was not significantly different at follow-up. Total retinal thickness was significantly thicker during and after the outdoor compared with the indoor and dark conditions. The outer segment + RPE was significantly thinner during the outdoor compared with the indoor condition but was not significantly different at follow-up. The inner segment was significantly thicker during the outdoor compared with the indoor and dark conditions during exposure and follow-up.

CONCLUSIONS

Spending 2 h outdoors under high-intensity sunlight resulted in an unexpected thinning of the choroid, which recovered post-exposure. Retinal thickness showed different responses to the outdoor and indoor environments and was sensitive to the duration of exposure.

Changes in physical activity and sedentary time among children with asthma during the COVID-19 pandemic and influencing factors

OBJECTIVE

Regular physical activity is essential for asthma control in children, but it remains understudied within the context of COVID-19. Physical activity and sedentary time levels before and during the COVID-19 pandemic among children with asthma were documented and differences by characteristics were explored.

METHODS

This was a cross-sectional self-administered online survey study of 5- to 17-year-old children with asthma from the United States between December 2020 and April 2021.

RESULTS

This study included 68 children with asthma. Although only 4.6% of the children were fully inactive before the pandemic, this number increased to 24.6% during the survey period (p < 0.001). Children spent significantly less time outdoors and more time in front of screens during the pandemic versus before (p < 0.001). The variety of activities in which children with asthma engaged in during the pandemic was lower than what they used to do prior to the COVID-19 crisis. Boys, Hispanic children, those of low-income households, and those not attending school in-person were significantly associated with less participation in physical activity during the pandemic. Ethnicity remained significantly associated after adjusting for multiple comparisons.

CONCLUSIONS

During the COVID-19 pandemic, children with asthma were less active and spent more time in front of screens and less time outdoors. Subgroup analyses revealed individual, parental, and organizational characteristics being associated with differential participation in physical activity, highlighting disparities in opportunities for children with asthma of different circumstances to remain active and healthy during the pandemic. Additional, more robust longitudinal studies are needed to confirm these results.

The outdoor time in non-myopic children has decreased to that of myopic children during the SARS-CoV-2 pandemic

Objective: Low levels of outdoor activity are known to be an important risk factor for the development of myopia in schoolchildren. This study aimed to determine outdoor and near work patterns in Polish schoolchildren before and during school closure due to the SARS-CoV-2 pandemic. Methods: All children undergoing a routine pediatric examination in the Elbląg branch of the Hygeia Clinic, together with their parents, were asked to fill an anonymous questionnaire. The subject's age, spherical equivalent (SE) refractive error, time spent outdoors, screen time and total near work in hours per day before and during the pandemic, were recorded. As substantial differences in physical activity by time of year were reported, activity patterns for June (summer) and December (winter) were recorded. Multiple logistic regression analysis was used to analyze the association between the presence of myopia and outdoor and total near work time at different timepoints. Results: A total of 61 schoolchildren aged 11.95 ± 2.74 (range 7 to 17) years were included in this study. The mean SE in the right eye was -1.78 ± 2.11 with 46% of the individuals (n=28) classified as myopic. Before the pandemic, higher time outdoors was associated with less myopic SE (OR=0.47, 95% Confidence Interval [CI] 0.24 to 0.93). During the pandemic, time outdoors among non-myopic children was similar to myopic children, both during winter and summer months (2.18 ± 1.81 vs. 1.89 ± 1.50; P=.51, and 3.47 ± 2.66 vs. 3.31 ± 1.65; P=.79 respectively). Time outdoors was not significantly associated with myopia during the pandemic (OR=1.17, 95% CI 0.64 to 2.14). Total near work was not associated with myopia at any time point. Conclusion: The long-term influence of the changing patterns of outdoor and near work on myopia prevalence and progression in our population is still to be established. Nevertheless, it is likely that the decrease of outdoor time may influence the rates of myopia in this region.

Near work, screen time, outdoor time and myopia in schoolchildren in the Sunflower Myopia AEEC Consortium

PURPOSE

To examine the association between near work, screen time including TV and outdoor time with myopia in children from the Sunflower Myopia Asian Eye Epidemiology Consortium (AEEC).

METHODS

We analysed AEEC cross-sectional data (12 241 children) on risk factors (near work, screen time including TV and outdoor time) and myopia of six population-based studies (China, Hong Kong and Singapore). Cycloplegic refraction and axial length (AL) measurements were included. Risk factors were determined using questionnaires. Data were pooled from each study, and multivariable regression analysis was performed to evaluate the associations between risks factors and myopia, spherical equivalent (SE) and AL.

RESULTS

Among the included children, 52.1% were boys, 98.1% were Chinese and 69.7% lived in urban areas. Mean±standard deviation (SD) for age was 8.8 ± 2.9 years, for SE was -0.14 ± 1.8 D and for AL was 23.3 ± 1.1 mm. Myopia prevalence was 30.6%. In multivariate analysis, more reading and writing (OR = 1.17; 95% CI, 1.11-1.24), more total near work (OR = 1.05; 95% CI, 1.02-1.09) and less outdoor time (OR = 0.82, 95% CI, 0.75-0.88) were associated with myopia (p's < 0.05). These factors were similarly associated with SE and AL (p's < 0.05), except for total near work and AL (p = 0.15). Screen time including TV was not significantly associated with myopia (p = 0.49), SE (p = 0.49) or AL (p = 0.83).

CONCLUSION

In this study, increased reading and writing and decreased outdoor time were associated with myopia. Screen time may be a surrogate factor of near work or outdoor time, but further research is needed to assess its role as an independent risk factor for myopia.

Time spent outdoors as an intervention for myopia prevention and control in children: an overview of systematic reviews

PURPOSE

Outdoor light exposure is considered a safe and effective strategy to reduce myopia development and aligns with existing public health initiatives to promote healthier lifestyles in children. However, it is unclear whether this strategy reduces myopia progression in eyes that are already myopic. This study aims to conduct an overview of systematic reviews (SRs) reporting time spent outdoors as a strategy to prevent myopia or slow its progression in children.

METHODS

We searched the Cochrane Library, EMBASE, MEDLINE and CINAHL from inception to 1 November 2020 to identify SRs that evaluated the association between outdoor light exposure and myopia development or progression in children. Outcomes included incident myopia, prevalent myopia and change in spherical equivalent refraction (SER) and axial length (AL) to evaluate annual rates of myopia progression. The methodological quality and risk of bias of included SRs were assessed using the AMSTAR-2 and ROBIS tools, respectively.

RESULTS

Seven SRs were identified, which included data from 47 primary studies with 63,920 participants. Pooled estimates (risk or odds ratios) consistently demonstrated that time outdoors was associated with a reduction in prevalence and incidence of myopia. In terms of slowing progression in eyes that were already myopic, the reported annual reductions in SER and AL from baseline were small (0.13-0.17 D) and regarded as clinically insignificant. Methodological quality assessment using AMSTAR-2 found that all reviews had one or more critical flaws and the ROBIS tool identified a low risk of bias in only two of the included SRs.

CONCLUSION

This overview found that increased exposure to outdoor light reduces myopia development. However, based on annual change in SER and AL, there is insufficient evidence for a clinically significant effect on myopia progression. The poor methodological quality and inconsistent reporting of the included systematic reviews reduce confidence in the estimates of effect.

Sociodemographic Predictors of Changes in Physical Activity, Screen Time, and Sleep among Toddlers and Preschoolers in Chile during the COVID-19 Pandemic

The aim was to examine the sociodemographic predictors associated with changes in movement behaviors (physical activity, screen time, and sleep) among toddlers and preschoolers during the early stages of the coronavirus disease 2019 pandemic in Chile. Caregivers of 1- to 5-year-old children completed an online survey between 30 March and 27 April 2020. Information about the child's movement behaviors before (retrospectively) and during the pandemic, as well as family characteristics were reported. In total, 3157 participants provided complete data (mean children age: 3.1 ± 1.38 years). During early stages of the pandemic, time spent in physical activity decreased, recreational screen time and sleep duration increased, and sleep quality declined. Toddlers and preschoolers with space to play at home and living in rural areas experienced an attenuated impact of the pandemic restrictions on their physical activity levels, screen time, and sleep quality. Older children, those whose caregivers were aged ≥35-<45 years and had a higher educational level, and those living in apartments had greater changes, mainly a decrease in total physical activity and increase in screen time. This study has shown the significant impact of the pandemic restrictions on movement behaviors in toddlers and preschoolers in Chile.

Sleep in Myopic and Non-Myopic Children

Purpose

To examine differences in sleep between myopic and non-myopic children.

Methods

Objective measurements of sleep, light exposure, and physical activity were collected from 91 children, aged 10 to 15 years, for two 14-day periods approximately 6 months apart. Sleep parameters were analyzed with respect to refractive error, season, day of the week, age, and sex.

Results

Myopic children exhibited differences in sleep duration by day of the week (P < 0.001) and season (P = 0.007). Additionally, myopic children exhibited shorter sleep latency than non-myopic children (P = 0.04). For all children, wake time was later (P < 0.001) and sleep duration was longer (P = 0.03) during the cooler season compared with the warmer season. On weekends, children went to bed later (P < 0.001), woke up later (P < 0.001), and had increased sleep duration (P < 0.001) than on weekdays. Younger children exhibited earlier bedtime (P = 0.005) and wake time (P = 0.01) than older children. Time spent outdoors was positively associated with sleep duration (P = 0.03), and daily physical activity was negatively associated with wake time (P < 0.001).

Conclusions

Myopic children tended to have more variable sleep duration and shorter latency than non-myopic children. Sleep patterns were influenced by season, day of the week, age, time outdoors, and activity.

Translational Relevance

Myopic children tended to have more variable sleep duration and shorter latency than non-myopic children, which may reflect previously reported differences in environmental and behavioral factors between refractive error groups.

2018 Chilean Physical Activity Report Card for Children and Adolescents: Full Report and International Comparisons

BACKGROUND

The study summarizes the findings of the 2018 Chilean Report Card (RC) on Physical Activity (PA) for Children and Adolescents and compares the results with the first Chilean RC and with other countries from the Global Matrix 3.0.

METHODS

A Research Work Group using a standardized methodology from the Global Matrix 3.0 awarded grades for 13 PA-related indicators based on the percentage of compliance for defined benchmarks. Different public data sets, government reports, and papers informed the indicators.

RESULTS

The grades assigned were for (1) "behaviors that contribute to overall PA levels": overall PA, D-; organized sport participation, D-; active play, INC; and active transportation, F; (2) "factors associated with cardiometabolic risk": sedentary behavior, C-; overweight and obesity, F; fitness, D; sleep, INC; and (3) "factors that influence PA": family and peers, F; school, D; inclusion, INC; community and built environment, B; government strategies and investments, B-.

CONCLUSIONS

Chile's grades remained low compared with the first RC. On the positive side, Chile is advancing in environmental and policy aspects. Our findings indicate that the implementation of new strategies should be developed through collaboration between different sectors to maximize effective investments for increasing PA and decreasing sedentary time among children and adolescents in Chile.

Outdoor physical activity, compliance with the physical activity, screen time, and sleep duration recommendations, and excess weight among adolescents

BACKGROUND

Spending time outdoor has been identified as an important way to achieve the physical activity required for maintaining and improving health and to lower sedentary time among young children. However, evidence of such relationships in adolescents is particularly limited. This study investigated the relationships between frequency of outdoor physical activity after school, compliance with the physical activity, screen time, and sleep duration recommendations, and overweight/obesity among adolescents.

METHODS

A total of 10 028 middle and high school students (mean age of 15.2 y) self-reported the number of weekdays they spent physically active outdoors after school. Physical activity, screen time, sleep duration, height, and weight were self-reported. Logistic regression models for the total sample and stratified by sex were adjusted for important covariates.

RESULTS

Overall, there was a positive gradient between the number of weekdays spent physically active outdoor after school and compliance with the physical activity (more than or equal to 60 min/day at moderate-to-vigorous intensity) and screen time (less than or equal to 2 h/day) recommendations while a negative gradient with overweight/obesity was observed. Significant sex differences were observed in the associations of outdoor physical activity after school with adherence to the sleep duration and physical activity recommendations. For example, outdoor physical activity after school on all 5 days was associated with greater odds of compliance with the sleep duration recommendation among males (OR = 1.53; 95% CI, 1.01-2.31), but not females (OR = 0.92; 95% CI, 0.65-1.30).

CONCLUSIONS

Results suggest that outdoor physical activity after school could be a behavioural target to increase compliance with the physical activity and screen time recommendations and to possibly tackle excess weight among adolescents.

The Impact of Shorter, More Frequent Outdoor Play Periods on Preschoolers' Physical Activity during Childcare: A Cluster Randomized Controlled Trial

Children's physical activity levels are higher at the start of outdoor playtime, which suggests that shorter, more frequent play periods might result in greater amounts of daily physical activity. In this extension of the Supporting Physical Activity in the Childcare Environment (SPACE) cluster randomized controlled trial, we explored the impact of four 30-min daily outdoor unstructured play periods on preschoolers' moderate-to-vigorous-intensity physical activity (MVPA). Experimental childcare centres (n = 6) implemented four 30-min daily outdoor playtimes for 8 weeks, while control centres (n = 6) maintained their two 60-min outdoor sessions. Actical™ accelerometers were used to measure preschoolers' physical activity pre- and post-intervention for 5 days during childcare hours. Linear mixed effects models were used to determine the impact of the intervention on preschoolers' MVPA. Of the 185 preschoolers enrolled (54.20% female; mean age = 39.90 months, SD = 7.24), 127 (65 experimental and 62 control) were included in the analysis (30% and 9% loss to follow-up for experimental and control group preschoolers, respectively). No significant differences in MVPA were observed between groups over time (p = 0.36). Preschoolers' MVPA did not improve after the introduction of shorter outdoor play periods. The loss of data due to wear time noncompliance and participant attrition may have influenced these findings. Trial registration: ISRCTN70604107 (October 8, 2014).

Environmental Correlates of Motor Competence in Children-The Skilled Kids Study

Environment, physical activity (PA) and motor development are tightly interwoven during childhood. We examined the associations of environmental factors with motor competence (MC) in children. Children (N = 945, 50.1% boys, age = 3-7 years, mean = 5.4 years) from 37 childcare centres in the Southern (n = 17), Central (n = 13) and Northern Finland (n = 7) participated. The environmental factors comprised the geographical location (Southern, Central and Northern Finland) and residential density (metropolitan area, city, rural area and countryside) of the childcare centres' based on postal codes and the national population density registry. MC was measured using the Test of Gross Motor Development (TGMD)-3, as well as by quantifying time spent outdoors and participation in organised sports via parental questionnaire. It was found that children from the countryside had better MC and spent most time outdoors, while children from the metropolitan area most frequently engaged in organised sports. Gender comparisons revealed that girls outperformed boys in locomotor skills, while boys were better in object control skills, had higher TGMD-3 score and spent more time outdoors. Time spent outdoors and participation in organised sports were associated positively with MC, but not in children from the countryside. In conclusion, higher population density was associated with lower MC and less time spent outdoors. The findings suggest that versatile outdoor environments may support motor development through PA.

Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review

Outdoor time is considered to reduce the risk of developing myopia. The purpose is to evaluate the evidence for association between time outdoors and (1) risk of onset of myopia (incident/prevalent myopia); (2) risk of a myopic shift in refractive error and c) risk of progression in myopes only. A systematic review followed by a meta-analysis and a dose-response analysis of relevant evidence from literature was conducted. PubMed, EMBASE and the Cochrane Library were searched for relevant papers. Of the 51 articles with relevant data, 25 were included in the meta-analysis and dose-response analysis. Twenty-three of the 25 articles involved children. Risk ratio (RR) for binary variables and weighted mean difference (WMD) for continuous variables were conducted. Mantel-Haenszel random-effects model was used to pool the data for meta-analysis. Statistical heterogeneity was assessed using the I² test with I²  ≥ 50% considered to indicate high heterogeneity. Additionally, subgroup analyses (based on participant's age, prevalence of myopia and study type) and sensitivity analyses were conducted. A significant protective effect of outdoor time was found for incident myopia (clinical trials: risk ratio (RR) = 0.536, 95% confidence interval (CI) = 0.338 to 0.850; longitudinal cohort studies: RR = 0.574, 95% CI = 0.395 to 0.834) and prevalent myopia (cross-sectional studies: OR = 0.964, 95% CI = 0.945 to 0.982). With dose-response analysis, an inverse nonlinear relationship was found with increased time outdoors reducing the risk of incident myopia. Also, pooled results from clinical trials indicated that when outdoor time was used as an intervention, there was a reduced myopic shift of -0.30 D (in both myopes and nonmyopes) compared with the control group (WMD = -0.30, 95% CI = -0.18 to -0.41) after 3 years of follow-up. However, when only myopes were considered, dose-response analysis did not find a relationship between time outdoors and myopic progression (R²  = 0.00064). Increased time outdoors is effective in preventing the onset of myopia as well as in slowing the myopic shift in refractive error. But paradoxically, outdoor time was not effective in slowing progression in eyes that were already myopic. Further studies evaluating effect of outdoor in various doses and objective measurements of time outdoors may help improve our understanding of the role played by outdoors in onset and management of myopia.

[Effect of vitamin D supplementation and outdoor time on the 25(OH)D level in adolescents]

OBJECTIVE

To assess the effect of vitamin D( VD) supplementation and outdoor time intervention on the 25( OH) D level in adolescents.

METHODS

In April2015, participants from three classes in a college of North Anhui were randomly assigned to VD supplementation group( receive oral vitamin D3 of 800 IU/d for 4 weeks, n = 55), outdoor time intervention group( more than 30 min/d of outdoor between 9 am and 15 pm for 4 weeks, n = 52) and control group( no any intervention, n = 63). The data on demographic characteristics, behavior related to vitamin D and life style were evaluated by using questionnaire. 25( OH) D level in finger-tip blood was measured by using LC-MS/MS. The differences of 25( OH) D levels among 3 groups over 4 weeks were compared.

RESULTS

On baseline, there was no significant difference( F = 0. 77, P = 0. 464) on the25( OH) D level among VD supplementation group( 15. 5 nmol/L, 95% CI 14. 3- 16. 6nmol/L), outdoor time intervention group( 16. 5nmol/L, 95% CI 15. 2- 17. 8 nmol/L)and control group( 16. 0 nmol/L, 95% CI 14. 9- 17. 1 nmol/L). However, the 25( OH)D level of VD supplementation group( 56. nmol/L, 95% CI 52. 0- 61. 6 nmol/L) and outdoor time intervention group( 54. 3 nmol/L, 95% CI 49. 4- 59. 3 nmol/L) were significantly higher( F = 4. 40, P = 0. 014) than that of the control group( 47. 2 nmol/L, 95% CI 42. 7- 51. 7 nmol/L) 4 weeks later. All participants among 3 group were all in VD deficiency( < 50 nmol/L) on baseline. After 4 weeks, the prevalence of VD deficiency among 3 group reduced to 40. 0%( 95% CI 27. 7%- 53. 2%), 48. 1%( 95%CI 34. 8%- 61. 5%) and 65. 1%( 95% CI 52. 9%- 76. 1%), respectively. Compared with the control, the risk of VD deficiency in VD supplementation group significantly decreased( RRadj= 0. 33, 95% CI 0. 15- 0. 72, P = 0. 005), and the risk in the outdoor time intervention group also obviously decreased( RRadj= 0. 48, 95% CI 0. 22- 1. 05, P = 0. 065), but did not reach statistical significance.

CONCLUSION

The 25( OH) D level of adolescents could be significantly improved through oral vitamin D3 supplementation of800 IU/d or more than 30 min/d of outdoor.

Low levels of vitamin D poorly responsive to daylight exposure in patients with therapy-resistant schizophrenia

BACKGROUND

Low vitamin D levels are associated with schizophrenia, but the possible association between vitamin D levels and illness severity or duration of exposure to daylight has barely been investigated.

AIMS

To compare vitamin D levels in therapy-refractory severely ill schizophrenia patients and members of staff. To investigate the influence of daylight exposure on vitamin D levels in patients.

METHODS

Vitamin D was measured in patients with therapy-resistant schizophrenia in April, after the winter, and in patients and staff members in June, after an exceptionally sunny spring. Vitamin D levels in April and June were compared in patients, and levels in June were compared in patients and staff. The influence of daylight was taken into account by comparing the time patients spent outdoors during the day with the recommended minimum time for adequate vitamin D synthesis, and by comparing time spent outdoors in patients and staff.

RESULTS

Patients had high rates of vitamin D deficiency (79-90%) and lower levels of vitamin D than staff members (p < 0.001), independent of skin pigmentation. In patients, vitamin D levels did not normalize, despite the considerably longer than recommended exposure of the skin to daylight (p < 0.001) and the longer exposure in patients than in staff members (p = 0.003).

CONCLUSION

The vitamin D deficiency of therapy-resistant schizophrenia patients is pronounced and cannot be explained by differences in skin pigmentation or by an inactive, indoor lifestyle on the ward. Even theoretically sufficient exposure of the patients to daylight did not ameliorate the low vitamin D levels.

CLINICAL IMPLICATIONS

While vitamin D deficiency probably plays a role in somatic health problems, it may also play a role in schizophrenia. Interestingly, exposure to daylight during an unusually sunny spring was not sufficient to correct the vitamin D deficiency seen in the patients. This emphasizes the need to measure and correct vitamin D levels in these patients.

What Is the Relationship between Outdoor Time and Physical Activity, Sedentary Behaviour, and Physical Fitness in Children? A Systematic Review

The objective of this systematic review was to examine the relationship between outdoor time and: (1) physical activity, (2) cardiorespiratory fitness, (3) musculoskeletal fitness, (4) sedentary behaviour; or (5) motor skill development in children aged 3-12 years. We identified 28 relevant studies that were assessed for quality using the GRADE framework. The systematic review revealed overall positive effects of outdoor time on physical activity, sedentary behaviour, and cardiorespiratory fitness, although causality could not be assumed due to a lack of RCTs. Motor skill development was unrelated to outdoor time; however, this relationship was only examined in a single study of preschool children. No studies were found that examined associations between outdoor time and musculoskeletal fitness.

The relationship between outdoor activity and health in older adults using GPS

Physical activity (PA) provides health benefits in older adults. Research suggests that exposure to nature and time spent outdoors may also have effects on health. Older adults are the least active segment of our population, and are likely to spend less time outdoors than other age groups. The relationship between time spent in PA, outdoor time, and various health outcomes was assessed for 117 older adults living in retirement communities. Participants wore an accelerometer and GPS device for 7 days. They also completed assessments of physical, cognitive, and emotional functioning. Analyses of variance were employed with a main and interaction effect tested for ±30 min PA and outdoor time. Significant differences were found for those who spent >30 min in PA or outdoors for depressive symptoms, fear of falling, and self-reported functioning. Time to complete a 400 m walk was significantly different by PA time only. QoL and cognitive functioning scores were not significantly different. The interactions were also not significant. This study is one of the first to demonstrate the feasibility of using accelerometer and GPS data concurrently to assess PA location in older adults. Future analyses will shed light on potential causal relationships and could inform guidelines for outdoor activity.