990: DISRUPTED TIME, DISRUPTED CARE: DST TRANSITIONS AND MEDICAL ERRORS IN HEALTHCARE SETTINGS

Introduction: Medical errors persist despite decades of individual-focused interventions. Research suggests many errors arise from cognitive-environmental interactions rather than personal failings. This study investigates how Daylight Saving Time (DST) transitions affect medical error rates using a natural experiment design. Methods: We conducted a retrospective observational study using Difference-in-Differences methodology, analyzing 7,933 medical error records from multiple healthcare facilities over six years (2019-2024). We compared error rates during the first two days following DST transitions to control periods (other Mondays and Tuesdays). Errors were categorized as medication, diagnostic, or surgical/procedural. We calculated Average Treatment Effects and conducted subgroup analyses by demographics. Results: DST transitions caused a 17.5% increase in medical errors (95% CI: 5.2% to 29.8%, p=0.0056). Conclusions: DST transitions are associated with a significant increase in medical errors, highlighting the impact of external temporal disruptions on clinical performance. These findings underscore the need to consider system-level and environmental factors—such as circadian misalignment—when developing strategies to improve patient safety.