Welcome to the Interactive Time Policy Impact Map

This interactive map visualizes the circadian health impacts of time policy across US counties.

Map Types

• Yearly Circadian Burden: Shows hours of circadian shifting per year under different time policies. Circadian shifting is computed using models of the human circadian rhythm's response to light exposure and captures the cumulative burden of trying to maintain sychrony with a 24-hour outer world.
• Health Outcomes: Visualizes predicted changes in obesity and stroke cases when switching from current policy (2025) to permanent Standard Time or permanent Daylight Saving Time.
• Hours from Time Zone Center: Displays how far east or west in hours each county is from its time zone's theoretical center.
• Population: Shows county population distribution

How to Use

• Select a map type from the dropdown to visualize different data
• Click on counties to view detailed information
• Select a state to see aggregated state-level data
• Use the time policy selectors to compare different scenarios
• Toggle time zone boundaries to see time zone divisions
• Toggle state boundaries to see state divisions
• Press Go to update the map

Data Source

This visualization is based on 2023 county-level data from the CDC Places dataset and mathematical models of the human circadian rhythm's response to light exposure patterns.

Published Paper

L. Weed, & J.M. Zeitzer, Circadian-informed modeling predicts regional variation in obesity and stroke outcomes under different permanent US time policies, Proc. Natl. Acad. Sci. U.S.A. 122 (38) e2508293122, https://doi.org/10.1073/pnas.2508293122 (2025).