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.
Every year we complain about War Time, as Daylight Saving Time was first known, developed to save energy and give farmers a bit more light. Except the First World War is over and we now have air conditioning and artificial lighting, so it doesn't actually save any energy at all.
This year, everyone is on about circadian rhythms. Sumathi Reddy of the Wall Street Journal speaks to Dr. Till Roenneberg of the University of Munich:
“Most of our physiology is governed by a circadian clock. This body clock synchronizes to the sun time”...When you travel to a different time zone your circadian clock adjusts to a new darkness-sunlight cycle in a few days. In daylight-saving time, the dark-light cycle doesn’t change but the time does. So there is a discrepancy between your biological clock and social clock, which researchers refer to as “social jet lag,” Dr. Roenneberg said. Permanent standard time is closer to the sun’s natural time so social jet lag is reduced, he added.
Now I have read this six times and it makes no sense, this difference between the biological clock and the social clock. In real solar time, Boston and Detroit are 45 minutes apart. Berlin and Madrid are 90 minutes apart. Which is running on biological time and which on "social time?" The Doctor continues:
“Daylight-saving time means that we virtually live in another time zone without changing the day-light cycle,” Dr. Roenneberg said. “The problem is the misalignment. The circadian clock is trying to optimize our physiology. Now suddenly we have to do things which are not at the biologically appropriate time.”
If one is going to make the case that there is a biologically appropriate time, then we not only have to get rid of daylight saving time, but we have to get rid of time zones altogether, which I proposed a few years ago, calling for local time. Noon used to be local, with over 300 time zones in the USA.
Then along comes the transcontinental railroad, and Sandford Fleming (the guy in the tall hat standing behind Lord Strathcona who is driving the last spike) figured out time zones so that everyone would be able to figure out where the trains were supposed to be. But we are not trains; noon should be noon wherever you are, not at 11:34 in Boston today and 12:42 in Detroit. What works for the convenience of Sandford Fleming and the railroads (and later, Walter Cronkite and the TV networks) doesn't work for our bodies.
If the science finds that there truly is a biological time, then the answer isn't just to get rid of DST. In this era of streaming entertainment and smart watches, it's time to run the trains and planes and conference calls on Coordinated Universal Time (UTC), and everything else on local time, noon where you live. More: It's time to get rid of time zones and go local and find out when it is solar noon where you live.
Does the time change cause heart attacks and car crashes?
We have noted that these time changes are really bad for your health, including an increase in the number of heart attacks and car crashes. But according to Paul Taylor, writing in the Globe and Mail, the research may be sketchy.
The research into the increase in the number of crashes was done by Stanley Coren, Ph.D. of the University of British Columbia, studying the rate of crashes on the first Monday after the switch. When he wrote his letter to the New England Journal of Medicine in 1996 it was still common to say accident instead of crash so I will not change that:
These data show that small changes in the amount of sleep that people get can have major consequences in everyday activities. The loss of merely one hour of sleep can increase the risk of traffic accidents. It is likely that the effects are due to sleep loss rather than a nonspecific disruption in circadian rhythm, since gaining an additional hour of sleep at the fall time shift seems to decrease the risk of accidents.
Others disagree with Dr. Koren and question the results; a doctor at Sunnybrook Hospital in Toronto looked at 16 different studies and concluded: “Looking at the sum total of evidence – and not just one cherry-picked study – my impression is that, if there is an association, it is modest.”
Then there is the question of heart attacks, which we have discussed before, which is based on a Swedish study which found that "heart-attack cases increased by about 5 per cent in the week after the clocks were adjusted – both in the spring and the autumn." Taylor questions that one too:
In particular, many studies that fail to show an effect don’t end up in the medical journals. “We tend to publish only the stuff that is interesting and will catch people’s attention. The papers that don’t find an association are less likely to be published,” [cardiologist Dr.] Ko says. That can lead people to conclude certain things have a greater impact than they actually do. Ko says he thinks the association between the daylight time switch and heart attacks is real. But, he adds, that risk is likely small and probably affects only those with existing heart disease.
Fine. But anyone with kids and dogs knows that this time change is totally disruptive, and really doesn't serve any purpose. Pick one and just keep it year round. Or even better, just go local time and forget about running on War Time, Railway time or Cronkite time, and go with Your Time.
Does the time change save energy?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.
Is the time change good for business?
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?