Crime Jumps When Clocks Turned Back: Study

October 30, 2015

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

Examining crime rates from 2005 to 2008, the university researchers found that robbery rates are lower during daylight savings time, the summer months when clocks have been advanced by one hour so that daylight is experienced an hour longer in the evening.

Ending daylight savings time by turning clocks back to Standard Time brings a seven percent increase in reported robberies — including a 27 percent jump in the hours just after and during sunset, according to the study.

Nicholas Sanders, assistant professor in the Cornell University Department of Policy Analysis and Management, co-authored the study with Jennifer Doleac, an assistant professor in the University of Virginia Batten School of Leadership and Public Policy. The findings are published online in The Review of Economics and Statistics as “Under the Cover of Darkness: How Ambient Light Influences Criminal Activity.”

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

Sanders said the research found no change in robbery for the sunrise hours. “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,” he said.

According to Sanders, the threat to public safety was likely greater prior to 2007, which is when the federal government extended daylight saving time by one week in the fall and three weeks in the spring. They estimate that the four-week daylight savings extension decreased annual robberies in the U.S., resulting in a social cost savings of at least $59 million per year.

Source: Cornell University

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