Sign Reversal Error Inverted East-West Circadian Burden in Prior US DST Health Study

The critique targets an earlier study linking seasonal clock changes to US health outcomes. The computational mistake effectively mapped Eastern health data onto Western time-zone solar times and vice versa, producing spurious correlations between disease rates and the wrong circadian load. Martín Olalla supplies corrected synchronization equations that align solar noon, standard time, and local longitude for each US county.

Correct modeling shows the largest post-transition circadian delay occurs in the easternmost portions of each time zone, where social clocks advance relative to sunrise by up to 90 minutes. This gradient was inverted in the flawed analysis, reversing the apparent risk map. The new guidelines specify that any circadian-DST model must integrate both the fixed longitude offset and the abrupt one-hour spring-forward shift rather than treating clock time as uniform within a zone.

Policy debates on permanent standard or daylight time now have a reproducible framework for estimating population-level sleep displacement. Future epidemiological work can re-analyze county-level data with the corrected offsets to test whether previously reported associations hold. Three additional replication studies using the proposed equations would provide the minimum evidence threshold for regulatory impact assessments.

The paper flags that animal-to-human extrapolation remains unsupported and that county-level exposure estimates still require individual-level validation through actigraphy or sleep diaries.