Robberies increase after time change

This weekend, most Americans are gaining an hour of sleep by turning back their clocks as daylight saving time ends. But, a newly published Cornell study finds, they could stand to lose much more in the time exchange.

Examining crime rates from 2005-08, Nicholas Sanders, assistant professor in the Cornell University Department of Policy Analysis and Management, co-authored a study with Jennifer Doleac, an assistant professor in the University of Virginia Batten School of Leadership and Public Policy. They found robbery rates are lower during DST. Standard Time brings a seven percent increase in reported robberies — including a 27 percent jump in the hours just after and during sunset.

The findings are published online in The Review of Economics and Statistics as “Under the Cover of Darkness: How Ambient Light Influences Criminal Activity.”

Sanders says:

“Most of the rise in crime occurs during weekdays, when commute times are concentrated around evening hours that are suddenly much darker.

“We found no change in robbery for hours that were dark both before and after daylight saving time – 10 p.m. – or light both before and after daylight savings time – like 3 p.m. Furthermore, we found no effects on crime rates for the sunrise hours, where daylight also shifts. It appears criminals aren’t early risers, and street crimes like robbery rarely take place in the early morning, even if it’s dark out.

“The threat to public safety was likely greater prior to 2007. That year, the federal government extended daylight saving time by one week in the fall and three weeks in the spring. That law change meant we could compare crime rates during commute hours from the same times of year. We estimate the four-week daylight savings extension, which lessened the early onset of darkness in the fall and added more daylight in the spring evening hours, decreased annual robberies in the U.S., resulting in a social cost savings of at least $59 million per year.”


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