Green Space, Mental Health and Sleep - Exposure to greenspace (i.e., various forms of outdoor vegetation) is associated with psychological, physiological, and environmental benefits for children across infancy, childhood, and adolescence.33-39 These benefits include higher birthweight (8-15g), improved mental health (17% reduction in stress, and anxiety), sleep (24% reduced risk of insufficient sleep),5,6,7 improved cognition (e.g., 5% increase in working memory) 17% fewer behavioral problems9 , reduced stress (15% to 21% steeper diurnal decline in cortisol) 4, and improved cardiometabolic outcomes (19% lower odds of high blood pressure) .10-13Possible mechanisms for these benefits include attenuation of air pollution and noise, as well as increased exposure to light, a zeitgeber of the circadian system1,19.However, children differentially experience access to the benefits of green space. Nationally, 50% of Hispanic children reside in census tracts with limited access to green space, compared to 23% of non-Hispanic White children14. Conversely, 63% of non-Hispanic White children live in communities with abundant green spaces, compared to 13% of Hispanic children. As the United Nations Children’s Fund indicates that green space exposure is necessary for the optimal growth and development of children, disparities in access to green space places children at increased risk for adverse health outcomes15. Notwithstanding, the lack of specificity regarding the definition, composition, and spatial delineation of greenspace limits arguments of causal inference. Consequently, the goal of this study is to fill these gaps by utilizing a longitudinal design that will better account for temporal and spatial relationships between cumulative greenspace exposure and multiple health and well-being outcomes in a sample of school-aged children. Specific aims: Aim 1. Determine how greenspace exposure (measured using top-down satellite imagery, GPS-derived measures of daily activity using commercially available wearables and a customized app) is related to sleep (duration, timing, regularity, rest-activity-rhythms), MVPA and mental health at multiple timepoints, accounting for latency periods between greenspace exposure, sleep and health behaviors and outcomes. Hypothesis 1.1 Children spending more time in greenspace as derived by GPS and satellite imagery will have earlier, longer, and more regular sleep and MVPA than children spending less time in greenspace. Hypothesis 1.2: Children spending more time in greenspace will have fewer mental health symptoms as measured by validated PROMIS® measures of anxiety, cognitive functioning, and psychological stress as indicated by objective biomarkers of stress, including IL-1β and TNF-α compared to children spending less time in greenspace. Hypothesis 1.3: Greenspace utilization will influence mental health and well-being through sleep behavior (duration, timing, regularity). Aim 2. Determine how greenspace exposure measured using street-level imagery is related to sleep, MVPA, and mental health among children. Hypothesis 2.1. Street-level measures of green space have a greater impact on childhood engagement and experiences with greenspace, and would have a stronger positive relationship with measures of sleep, MVPA, and mental health. Aim 3. Exploratory Aim. Explore epigenetic clocks as mediators between greenspace, sleep and mental health, and use computational modeling to develop and test clocks for children.
