Should We Keep Changing the Clock? Characterizing Causal Effects of Daylight Saving Time on Behavior and Physiology.

ABSTRACT: Daylight Saving Time (DST) remains contentious: some policymakers highlight behavioral benefits, while others emphasize health risks. Existing evidence relies largely on aggregated data and strict modeling assumptions, obscuring individual-level patterns and yielding associational rather than causal insights. We address these limitations using objective, longitudinal Fitbit measures from the NIH All of Us Research Program. Avoiding strict modeling assumptions, we employed a natural difference-in-differences design using Arizona (no DST) as a control against neighboring Mountain Time states (observing DST). Contrary to the common belief, DST transitions produced no net change in total daily steps. Instead, activity was reallocated to other times of day: fall transitions increased mor

SUBMITTER: Jeong H 

PROVIDER: S-EPMC12838301 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature