Recurrent power outages and the mental health burden of grid reliability in Maryland.

Power outages are increasingly shaped by aging infrastructure, climate stress, and rising electricity demand. Their mental health consequences remain poorly quantified, particularly for routine outages outside major disasters. Here, we link 15-min outage records with Maryland Healthcare Cost and Utilization Project State Inpatient Database records from 2018 to 2023 and estimate ZIP-quarter associations with hospitalizations for primary mental health diagnoses. Higher outage exposure was consistently associated with increased hospitalization rates in Poisson pseudo-maximum likelihood models with ZIP code and year-quarter fixed effects and controls for weather, socioeconomic conditions, demographics, healthcare access, and comorbidity. The baseline incidence rate ratio was approximately 1.017, equivalent to a 1.7% increase per one-unit increase in logged outage episodes. Results were robust to alternative thresholds and concentrated among frequent 1-3h disruptions. Instrumental-variable analyses based on grid infrastructure yielded larger positive estimates. These findings suggest that grid reliability is a climate-adaptation and health-system continuity issue.