Daylight Saving Time, Saving Energy, Saving Lives?

I don’t think I ever fully realized how fraught the concept of Daylight Saving Time was and what controversy surrounds “falling back” or “springing ahead” an hour.

Disorienting? Sure.

Annoying? Occasionally.

But life-threatening? Seems a touch dramatic.

Yet NPR highlighted a study finding an increase in violent street crime and robbery that occurs when we “lose” an hour of daylight in fall evenings. Apparently robbers like to sleep in as much as I do.

(But I doubt they’re aware of the price of that extra hour of shadowy mischief-making: they and everyone else also have an increased risk of heart attacks, traffic accidents, and injuries in the workplace on the Monday immediately following the end of Daylight Saving Time. Researchers tend to blame disruptions to sleep patterns for some of these effects.)

Economists Jennifer Doleac of the University of Virginia and and Nicholas Sanders of William and Mary took advantage of the Energy Policy Act of 2005 extending Daylight Saving Time (DST) by an extra three weeks in the spring and one week in the fall. They compared neighborhood crime rates during the switch to DST in spring and fall of 2005 and 2006, before the law took effect, and with the same time periods in 2007 and 2008. Their study [PDF] uncovered a 7% drop overall in robberies after DST takes effect, stealing an extra hour of darkness from the evenings when ne’er-do-wells would prefer to not do well and take your wallet under the cover of darkness.

So, Daylight Saving Time may save you from getting hit by a car and hit up by a robber, but does it live up to its perennial justification of saving energy?

Well, various reports conclude that … it depends.

If you live in Indiana, then it may slightly increase residential energy use [PDF]. (This state actually used to be split, with some counties observing DST and others never paying attention to a time change. Having lived there during that time, I can attest that was truly annoying.)

If you live in California, it may actually sorta save some energy (perhaps 0.93% of your daily energy bill [PDF]).

And if you live in all of the United States at the same time (I think that’s how national averages work), extending Daylight Saving Time cuts about 0.03% of annual U.S. electricity consumption [PDF], which is at least better than a coal-fired punch in the face.

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