LAUSR

ObjectivesThe purpose of this study was to test the effect of a mild, short-term sleep loss/gain on assault rates.MethodsUsing National Incidence Based Reporting System data and city-reported data from Chicago, New York, Philadelphia, and Los Angeles, we calculated the difference in assault rates on the Monday immediately following daylight saving time (DST) as compared to the Monday a week later using a Poisson quasi-maximum likelihood estimator model. The same analyses were performed to examine effects of the return to standard time in the fall. We employed several falsification checks.ResultsThere were 2.9% fewer (95% CI: –4.2%, −1.6%, p < 0.0001) assaults immediately following DST, when we lose an hour, as compared to a week later. In contrast, there was a 2.8% rise in assaults immediately following the return to standard time, when an hour is gained, as compared to a week later (95% CI: 1.5%, 4.2%, p < 0.0001). Multiple falsification analyses suggest the spring findings to be robust, while the evidence to support the fall findings is weaker.ConclusionsThis study suggests that mild and short-term changes in sleep do significantly affect rates of assault. Specifically, there is support for the theory that mild sleepiness possibly associated with an hour loss of sleep results in reduced assaults. This contradicts the simple inverse relationship currently suggested by most of the correlational literature. This study and the mixed findings presented by experimental studies indicate that measurement variability of both sleep and aggression may result in conflicting findings.