New Research: Circadian Health Impacts of US Time Policy
I’m pleased to share our latest publication in PNAS, titled “Circadian-Informed Modeling Predicts Regional Variation in Obesity and Stroke Outcomes Under Different Permanent US Time Policies,” where we used the latest circadian models paired with data from the CDC to examine the health impact of permanent Standard Time, permanent Daylight Saving Time, and our current policy of switching between the two.
Figure 1: Yearly circadian burden predicted by our modeling under biannual switching, permanent Standard Time, and permanent Daylight Saving Time for early, intermediate, and late chronotypes.
Our data indicate that switching to permanent Standard Time would reduce prevalence of obesity by 2.6 million cases and stroke by 0.3 million cases in the continental US. Switching to Standard Time would reduce cases the most, but choosing either permanent time policy is better than our current time policy of switching between SDT and DST.
Figure 2: Change in obesity prevalences by switching from the current policy of biannually switching to permanent Standard Time or Permanent DST in the contiguous continental US. Switching from our current policy to permanent Standard Time reduces overall obesity prevalence more than switching to permanent Daylight Saving Time. Adapted from Weed and Zeitzer (2025).
This work is just one piece of the puzzle in policy decisions around time policy. We sought to answer the question from a circadian health perspective, though there are many other perspectives (e.g., economic, safety, etc.) that may be important to jointly consider. We hope that this work will help policy makers make a more informed decision.
I’d like to thank my PI, Jamie Zeitzer, for supporting and guiding me in this work as well as for always being the most thorough reviewer. I’d also like to thank NIH NHLBI for funding me through a NRSA F31 predoctoral fellowship, enabling this work. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
