JAMA Netw Open

Daylight saving time not linked to increased MI risk, large registry study finds

September 11, 2025

Study details: This cross-sectional study analyzed data from 168,870 patients (median age, 65 years; 34% women) hospitalized with acute MI (AMI) between 2013 and 2022, using the National Cardiovascular Data Registry Chest Pain–MI Registry. Researchers compared AMI incidence and in-hospital outcomes during the week before, during, and after both spring and fall daylight saving time (DST) transitions across 1,124 U.S. hospitals.

Results: There were no significant differences in AMI incidence during DST weeks compared with the week before or after. Similarly, adjusted in-hospital outcomes—including mortality, stroke, and revascularization rates—didn’t differ across time periods. These findings held true for both spring and fall transitions.

Clinical impact: Contrary to earlier studies suggesting an increase in AMI following DST changes, this large contemporary analysis found no evidence of elevated CV risk. These results may help reassure clinicians and patients and suggest that DST transitions don't warrant changes in CV risk management strategies.

Source:

Rymer JA, et al. (2025, September 2). JAMA Netw Open. Daylight Savings Time and Acute Myocardial Infarction. https://pubmed.ncbi.nlm.nih.gov/40924425/