A ten-year study from Duke University Medical Center found no significant changes in the number or severity of heart attacks after spring or fall time changes. The research examined data from more than 1,100 hospitals between 2013 and 2022, challenging earlier claims that daylight saving time increases cardiac events.
The research team, led by Jennifer Rymer, an interventional cardiologist with Duke University Medical Center, examined information from hospitals participating in the Chest Pain MI Registry. About 28,000 people each week were treated for heart attacks before, during, and after the clock shifts. No consistent week-to-week differences appeared in heart attack incidence or in-hospital outcomes.
“To our knowledge, this is the largest analysis to date of the association of incidence of AMI [acute myocardial infarction, the scientific term for heart attack] and [daylight saving time],” Rymer’s team reports in the September 2025 issue of JAMA Network Open. Nearly 170,000 patients across the nine-year period were included…