Does Daylight Saving Time Affect Crime? Assaults Rise By About 3 Percent After The Clock Falls Back

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People around the U.S. will get an extra hour of sleep on Sunday, Nov. 5, as their clocks fall back an hour and Daylight Saving Time ends. You're likely grateful for that extra shuteye, but the time change may bring something you aren't expecting: a higher risk of crime in your area. A new study found that assaults increase right after daylight saving time ends, and decrease right after it begins, too. The research was conducted by scientists at the University of Pennsylvania who specialize in criminology, psychiatry, and psychology. The objective of the study, published in the Journal of Experimental Criminology, was to "test the effect of a mild, short-term sleep loss/gain on assault rates."

The research team used the National Incident-Based Reporting System, an FBI data collection program, to look at crime rates in Chicago, New York, Philadelphia and Los Angeles the Monday after daylight saving time began (back in the spring) and then analyzed crime rates from the following Monday. They also looked at crime data for the Monday after daylight saving time ended and the Monday immediately following. I'm much more pleasant when I've gotten a good night's rest, so I assumed sleeping more would make people less likely to commit crime. I wasn't too far off with my thought process: Researchers had the same hypothesis when they started out, as drowsiness has been linked to violence in the past.  

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Surprisingly, the study authors found the opposite to be true. The day after daylight saving time starts in March, when people have lost an hour of sleep, assaults are down nearly 3 percent. In contrast, right after daylight saving time ends in November, assaults are up by roughly the same percentage.

“Sleep problems have previously been associated with increased antisocial and criminal behavior, so we were surprised to find that increased sleep was associated with increased offending,” said study author Adrian Raine in a release from the University of Pennsylvania. “This discrepancy is likely due to the fact that 40 to 60 minutes of lost sleep in one night is just not the same as months, or even years, of poor sleep.”

The research team said the evidence supporting crimes increasing after daylight saving time ends isn't as strong as the results about crimes decreasing. Still, the trend is interesting, and provides "support for the theory that mild sleepiness possibly associated with an hour loss of sleep results in reduced assaults," according to the journal article.

Long-term sleep loss can still have physical and psychological risks, so this isn't cause to pull all-nighters all the time. But short-term, losing some sleep might be good for society. Basically, even though you may be grouchy because you didn't get enough rest, you're likely too tired to attack the people around you. According to Raine, "You’re too lethargic and sleepy to act.”

The study also says this may be a reason to avoid hitting the beloved snooze button when you're waking up.

“Before we hit that snooze button, perhaps we should stop and think,” Raine said in the release. “Hit the button and we might end up at least a little grumpier at work, and possibly more aggressive.”

As you prepare for the harsh winter days ahead, you may find solace in the end of daylight saving time, even though this study says that extra hour of sleep may do more harm than good. Because assaults increased by less than 3 percent, you won't need to shut yourself inside this Monday — your chances of being the victim of a crime are still relatively low. But if you catch yourself feeling agitated over the weekend even though you got more sleep than usual, you'll have an idea why.