Abstract Body: Background: Psychological stress during childhood can disrupt vascular homeostasis and increase long-term cardiovascular disease (CVD) risk. Endothelin-1 (ET-1), a potent vasoconstrictor involved in endothelial dysfunction, oxidative stress, and vascular inflammation, has been proposed as a biomarker of cardiovascular risk. While adult populations show a link between stress and elevated ET-1, evidence in pediatric populations is scarce.

Objective: To determine the relationship between psychosocial stress, sleep quality, and ET-1 levels in a pediatric population in Puerto Rico.

Methods: Children were recruited from the Puerto Rico Health Justice Center and pediatric community clinics. Participants completed PROMIS Pediatric measures (stress, sleep, and family relations), self-reported trauma history, and clinical evaluations for BMI, blood pressure, and lipid profiles. Plasma ET-1 concentrations were quantified from blood samples. Thirty-eight Hispanic participants (mean age = 12.1 ± 2.3 years; 73% female) were analyzed.

Results: Eleven participants (29%) exhibited elevated ET-1 levels. Higher PROMIS stress scores correlated with higher ET-1 concentrations (p < 0.05). Children with poor sleep quality showed significantly higher ET-1 levels (median = 1.7 vs. 0.8 pg/mL, p < 0.01). The coexistence of poor sleep and high stress further amplified ET-1 elevation, suggesting cumulative vascular effects. Participants with high ET-1, high stress, and poor sleep also had a greater frequency of dyslipidemia.

Conclusion: Psychological stress and poor sleep are biologically linked to endothelial dysfunction in Hispanic children, as reflected by elevated ET-1 levels. ET-1 may serve as an early biomarker of stress-related cardiovascular vulnerability, underscoring the need for integrated behavioral and physiological interventions in pediatric populations.