Living in the wrong time zone: Elevated risk of traffic fatalities in eccentric time localities

Abstract

Chronobiology research has uncovered a host of maladies linked to social jetlag (SJL), the sleep-disrupting disconnect between solar time and social time. This interdisciplinary study applies chronobiology theory to the potential effect of misaligned time zones on motor-vehicle deaths. In the U.S. 53 million residents live in counties located outside their official time zones’ standard 15° span of longitude, based on degrees west of the prime meridian. We refer to these counties as eccentric time localities (ETLs), all of which lie west of their time zones’ standard western border in the U.S. In contrast, counties within 7.5° of their time zone’s standard geographic center are what we call solar zones. Solar zones do not vary more than 30 minutes from true solar time. ETL residents are forced to rise before dawn, possibly restricting their sleep-time and suppressing both morning and evening zeitgebers that would support their circadian entrainment. Hypothesizing that living in ETLs amplifies social jetlag, data on 417,399 traffic fatalities in the U.S. between 2006 and 2017 from the Fatality Analysis Reporting System (FARS) census were analyzed via GIS mapping and population-data statistics. Road fatalities among residents of solar zones were compared to those living in ETLs within the same official time zone. ETL residents across the U.S. indicated 21.8% higher fatality-rates than solar residents, with a mean of 1286 additional (i.e., unexpected) deaths-per-year. Results support circadian entrainment theory and are consistent with the SJL construct. The socio-political ramifications of these findings are discussed, as well as the subject of best practices when analyzing whole-population data. The authors conclude that the unquestioned rhetoric of time-zone boundaries should be reconsidered in social policy.