This is a rolling post that we bring back and update every year with the latest research into the folly that is Daylight Saving Time. The poll has been set to zero but the comments carry on forever.
It's that time of year when we lose an hour of sleep and turn our clocks forward thanks to the introduction of Daylight Saving Time, which probably made a lot of sense back in 1916 when it started as a fuel-saving measure in World War 1. Every year we look at this change and every year find more evidence that it really should be scrapped already, and that thanks to the prevalence of air conditioning, it now actually increases energy consumption.
One of the justifications for maintaining DST is that is good for business; it has been thought that the extra light in the evening meant more people in stores. This was recently studied by JP Morgan Chase in Shedding Light on Daylight Savings Time, where they compared sales receipts in Los Angeles, where there is DST, to Phoenix, which is in one of the few states that does not switch to DST.
And indeed, Los Angeles showed that the extra hour of daylight increased sales in stores by about one percent. However this was swamped the the loss of sales, a drop of 3.5 percent, when the clocks were turned back in November. In total, throughout the year, the effect appears to be more negative than positive.
The increase in spending at the beginning of DST is determined by comparing daily card spending per capita in the 30 days before DST starts, to daily card spending per capita in the 30 days after DST starts. The decrease at the end captures a similar window to compare spending in the 30 days before and after the end of DST. Most of the impact stems from responses at the end of DST, when spending on goods drops more than spending on services, and spending during the work week drops more than weekend spending. The magnitude of the spending reductions outweighs increased spending at the beginning of DST.
The shock of the dark evenings in November keeps people out of stores more than the extra hour in the spring brings them in. And now that online shopping is an available option, there is even less reason to subject people to this change, which is not very good for our health:
DST can kill youIn 2016 we reported on a study described in STAT which suggests that switching to Daylight Saving Time can kill you.
A 2013 study of nearly 1,000 patients at two Michigan hospitals compared admissions for heart attacks during the seven days after the move to daylight saving to the same days two weeks prior. In the study, which looked at data between 2006 and 2012, researchers found 17 percent more heart attacks after “springing ahead,” with a 71 percent spike on the first day, Sunday. In fact, that one day accounted for almost all of the overall increase.
It's not just heart attacks either.
Analyzing a decade worth of strokes in Finland, scientists found a brief spike in the incidence of ischemic stroke (the most common kind, caused by a clot blocking blood flow in the brain) after the clocks are turned ahead compared to the week before. The rate was 8 percent higher during the first two days after setting the clocks ahead, Dr. Jori Ruuskanen of Finland’s University of Turku and colleagues reported. But in people over 65, the incidence of stroke on those Sundays and Mondays was 20 percent higher.
John Oliver is not a fan of DST,
and is quite funny about it:
However there is one positive effect: apparently there is a sharp reduction in street crime rates. According to Business Insider, a recently published paper shows that the extra light in the afternoon discourages potential offenders.
Results show that daily cases of robbery, a violent and socially costly street crime, decrease by approximately 7% in the weeks after DST begins, with a 19% drop in the probability of any robbery occurring. A 27% decrease in the robbery rate during the sunset hours drives much of this result.
Ending DST could solve climate changeA few years back, the transition to Daylight Saving Time happened on April 1st, so of course we calculated impact of an extra hour of sunlight had on the world and announced that ending DST could solve global warming.
TreeHugger Labs ran the numbers and has determined that If DST runs half the year for an hour a day, that is fully 1/48th of our total exposure to the sun that could be eliminated with the cancelling of Daylight Saving Time, almost 2% of solar heat gain annually.That's huge!
A surprising number of readers were convinced. In 2007 the Arkansas Democrat published a letter complaining about the earlier start of DST:
You would think that members of Congress would have considered the warming effect that an extra hour of sunlight would have on our climate. Perhaps this is another plot by a liberal congress to make us believe that global warming is a real threat.
Silliness aside, Brian Merchant looked at the issue and concluded that Daylight Savings Time actually increases electrical demand, as air conditioning has eclipsed lighting as the main use of electricity.
Brad Plumer in the Washington Post summarizes the effects of DST and quotes the same study Brian did, finding that DST increases energy consumption, can be bad for your health, has mixed effects on the economy:
Retailers love the extra sunlight — it means that there are more customers around who are willing to go out and shop. The all-powerful golfing industry is also a big fan, apparently. On the other hand, daylight saving can cut into sales for movie theaters and reduce the audience for prime-time television — people go out and enjoy the evening air instead of staring at screens inside.
Perhaps it's time to scrap Daylight Saving Time. What do you think?