Screen time and allostatic load among youth: findings from the National Health and Nutrition Examination Survey, 2015-2018

BACKGROUND: More screen time (ST) is associated with dysregulation of the individual biological systems (cardiovascular, immune, metabolic, and neuroendocrine) involved in the stress response in youth. However, its relationship with allostatic load (AL), a measure of the cumulative physiological stress response, is unclear in youth. PURPOSE: To investigate the associations between ST types and AL outcomes in youth and to explore sociodemographic and behavioral moderators of these relationships. METHODS: Cross-sectional data were from 1053 US youth aged 12-17 years (Mage = 14.20; 54% male; 21% Hispanic) in the 2015-2018 National Health and Nutrition Examination Survey (NHANES). ST was assessed as watching TV/videos and computer use/playing computer games. AL was measured using 7 biomarkers across 3 systems: cardiovascular (systolic and diastolic blood pressure, heart rate), immune (C-reactive protein), and metabolic (body mass index, glycohemoglobin, and high-density lipoprotein). Weighted multivariable regression models assessed whether ST predicted AL composite and subsystem (cardiovascular, immune, and metabolic) scores. Moderation by age, sex, income, race/ethnicity, and physical activity was explored. RESULTS: A 1-hour/day increase in watching TV/videos was associated with a 4% increase in mean AL composite score (incident rate ratio = 1.040; 95% CI = 1.008, 1.073; P = .015), while computer use/gaming showed no significant associations (P's > .05). Age moderated the TV/videos-AL cardiovascular association (P = .009), with older youth having higher AL cardiovascular scores. CONCLUSIONS: More time spent watching TV/videos was associated with higher cumulative physiological stress in youth. Prospective studies are needed to determine causal pathways and potential intervention targets in youth.