Daylight Saving Time Myths

What does daylight saving time really do for us, and what are the real reasons we have it?

by Brian Dunning

Filed under General Science, Urban Legends

Skeptoid #172
September 22, 2009
Podcast transcript | Listen | Subscribe
 

Today we're going to turn our clock back (or forward, as the case may be) and screw up our sleep cycles, casting everything into disarray for a good week until we recover — for today's topic is daylight saving time: The myths, the fallacies, and the facts. Why on Earth would we ever want to change our clocks a few times a year? Is it actually a good idea? In today's day and age, is it still good, or is it outdated?

Benjamin Franklin is often credited with inventing the concept of daylight saving time, on the principle of conserving candles. However, a closer look at this popular tale reveals cause for skepticism. Franklin's paper was actually a satire poking fun at the partying lifestyle of Parisians, not a serious recommendation. It was a letter written in 1784 for the Journal de Paris in which he proposed firing cannons at sunrise to wake people up and break them from their nocturnal habits. To justify this, he suggested that sleeping instead of burning candles all night long would save Parisians 64 million pounds of candle wax over six months.

The first serious propositions came independently from different sides of the world a century later: from New Zealander George Hudson in 1895, and Englishman William Wennett in 1907. Both recommendations were to provide for additional sunlit leisure time after work, and it was proposed for use in the summertime only because if it were done in winter, the shorter days would force morning activities (like children walking to school) to happen while it was still dark. That's why we have the current schedule of observing daylight saving only in the summertime: Our workday squeezes into the middle of that narrow band of daylight during the winter, and it drops down to the bottom of the wider band of daylight in the summer; keeping our morning wakeup times roughly aligned with sunrise, but giving us an abundance of extra daylit playtime after work when the days are long enough to permit.

Perhaps the most pervasive popular perception about daylight saving time is that it's all about farmers, the idea being that certain farm tasks should be done at sunrise, whether it's milking cows or watering or harvesting crops, and changing the clock makes this easier somehow. The obvious response to this is that these tasks are going to continue to be done at sunrise, regardless of the time shown on some irrelevant clock. When you dig in and read the arguments for or against daylight saving put forth by various groups, farmers are said to be among the most vocal opponents of daylight saving. Here's a quote that I must have found a hundred times in different sources, word for word:

Farmers, who must wake with the sun no matter what time their clock says, are greatly inconvenienced by having to change their schedule in order to sell their crops to people who observe daylight saving time.

No matter how many times I found that same sentence, I could never discover its original source. The concept is illogical at face value. In the morning hours, daylight saving's effect is to keep the clock more in line with sunrise: i.e., 6:00am comes an hour earlier in the summer when the sun is rising earlier. If farmers need workers to arrive when the sun starts drying the dew, daylight saving is clearly their friend. I found many, many articles repeating the presumption that farmers oppose daylight saving, but almost nowhere did I find a good reason articulated; at least not one that pertains to farming. The president of the New South Wales Farmers Association could only come up with this argument:

Daylight saving has a significant adverse impact on rural families and communities businesses. An example is children traveling home from school in the heat of early afternoon sun. Members also say they have trouble getting their children to bed at normal bed times, and farmers indicate that they work longer days.

...which says nothing about daylight saving creating a problem for the practice of farming. At the same time, other farmers express the same pleasure as other people at an extra hour of sunlit family recreation time after a summer workday.

Dairy farmers have the closest thing to a cogent argument that I could find. Let's say that their product has to be to market at a given clock time, and twice a year the clock changes by an hour. This forces the cows to be milked at a 23 or 25 hour interval, once each year, instead the 24 hour interval to which they're accustomed. Evidently this disruption to the cow's schedule is problematic for the cow. If this really is a significant problem for cows, it constitutes one of only two farm-related arguments against daylight saving that I could dig up.

The other is not unique to farms, and has to do with moving heavy equipment on roads in the early morning. Many such vehicles can only be driven during daylight, and many of the rest shouldn't be operated in darkness for safety reasons. When daylight saving drops the working man's start time down closer to sunrise during the summer, this problem is prolonged for more of the year. But I'm still not convinced by this argument's logic. Farm work starts with the sun. Safe equipment operation starts with the sun. That's how it's always going to be. Daylight saving keeps the clock time at the beginning of the workday more consistent with sunrise year round, so, from a rational perspective, the people who depend on the morning sun for their job have every reason to be the biggest supporters of daylight saving: It brings them better consistency.

So now we come to what everyone believes, and what's written down on paper as the official reason we observe daylight saving time: The conservation of electricity. The idea is that residential power usage is reduced because people don't have to turn their lights on until an hour later in the summer. This was indeed true the first time the question was deeply studied, which was during the oil crisis of the 1970's. The Department of Transportation calculated a 100,000-barrel savings in oil, from a 1% savings in power usage, compared to if we'd stayed on standard time. However, in the decades since then, air conditioning has become much more ubiquitous, and its power consumption greatly outpaces the reduction in lighting — although this is slightly offset by reduced heating on fall and spring mornings. In addition, people have many more electronic gizmos around the house then they did in the 1970's. Having people at home for an extra hour is not nearly such a great way to conserve electricity as it used to be.

Nowadays, people studying power usage during daylight saving get mixed results. There's a lot of regional variation. Places like Florida, with maximum air conditioning needs, clearly use more electricity because of daylight saving; while cooler northern states may still see overall savings due to reduced lighting needs. Generally, reports of national energy consumption combine results from a cross section of utility companies nationwide. Depending on what utilities you include in your report, you may get very different overall results. A truly comprehensive report that accounts for all data is probably outside the realm of practicality.

Tip Skeptoid $2/mo $5/mo $10/mo One time

If you do a Google search for daylight saving energy consumption, you'll find reports are all over the map. In fact, the year after the Department of Transportation found a 1% savings, the National Bureau of Standards reviewed their data and found no savings. Some reports find that it uses as much as 1-2% additional electricity; some find there's a savings of as much as 1-2%. Most fall within the statistical margin of error. The one statement I'd feel comfortable making with authority is that any possible energy savings that may be derived from daylight saving time is statistically insignificant.

There's one powerful reason that daylight saving is probably here to stay, and it has nothing to do with farms or electricity or road safety. Strong reasons usually have to do with money. Not money that you send to your utility company, but money that you hand over at the cash register. During the warm summer months when it's possible to do so in comfort, people like to be out and about in the evening. They like to go out for dinner, drinks, or a movie, or wander through stores and galleries. They also like to play golf and tennis. Whenever they do these things, they spend money. Lots of money, in the collective. Give them an extra hour to recreate in the summer, and they spend even more money. In 1986, an extra month of daylight saving was added to the calendar, and representatives of various recreational industries appeared in front of Congress to testify about the effect it had on their bottom lines. The golf industry is said to have benefited by an additional $200 million, just from that one additional month; and the barbecue industry is said to have sold an additional $100 million in barbecues and charcoal briquettes. The additional extension in 2007 into November was supported strongly by the candy industry, who can sell a lot more Halloween candy when kids can spend an extra hour trick or treating before bedtime.

There is even a certain lobby out there that points to the environmental impact of this extra hour of shopping, dining, and golf. One paper from UC Santa Barbara calculated the cost of the resulting pollution as several million dollars per year. Whatever your particular fancy, you can probably find someone who's written a paper saying that daylight saving is good or bad for it. Daylight saving is one case where the fewer words you use to describe it, the more accurate you are. One word: Money. The more details you go into beyond that, the more treacherous your footing.

Brian Dunning

© 2009 Skeptoid Media, Inc. Copyright information

References & Further Reading

AAP. "NSW: Farmers work longer and kids won't go to sleep: association." AAP General News Wire. 22 Oct. 2007, Wire: 1.

Aries, M.B.C., Newsham, G.R. "Effect of daylight saving time on lighting energy use: A literature review." Energy Policy. 1 Jun. 2008, Volume 36, Issue 6: 1858-1866.

Choi, C. "Does Daylight Saving Time Conserve Energy?" Scientific American. 5 Mar. 2009, Volume 301, Number 3.

Downing, Michael. Spring Forward: The Annual Madness of Daylight Saving Time. Berkeley: Shoemaker & Hoard, 2005. 147-151.

Franklin, B., Goodman, N. The ingenious Dr. Franklin: selected scientific letters of Benjamin Franklin. Philadelphia: University of Pennsylvania Press, 1931. 17-22.

Kotchen, M.J., Grant, L.E. "Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana." NBER Working Paper Series. National Bureau of Economic Research, 1 Oct. 2008. Web. 22 Sep. 2009. <http://www2.bren.ucsb.edu/~kotchen/links/DSTpaper.pdf>

Reference this article:
Dunning, B. "Daylight Saving Time Myths." Skeptoid Podcast. Skeptoid Media, Inc., 22 Sep 2009. Web. 1 Nov 2014. <http://skeptoid.com/episodes/4172>

Discuss!

10 most recent comments | Show all 72 comments

Stuart raises a point about surfing and clean waves generally occurring in the morning. The same goes for fishing, the daybreak usually being much less windy and conditions far more pleasant.

For those who wake up with the light, DLS can be a little irritating as the normal waking time is closer to yours and you get surf competition.

Down where I have to slave for fun and games you note that the old coots get up early all year round and the employment entertained follow with the young generally being the last.

Thank goodness teenagers really seem to need their sleep, they are so fit its nigh on impossible to get waves amongst their social strutures as an old codger.

Good on them! They give us about an hour or two in summer DLS or not.

Mellifluous Dintpod, sin city, Oz
August 9, 2013 6:13pm

They tried to institute daylight savings here in WA and we gave it a two-year trial run.

The sun set a 9PM.

Needless to say it got voted out.

Jimi, Perth
September 5, 2013 5:33am

"The sun set a 9PM.

Needless to say it got voted out."

This is my favorite part about it.

I love the part of the year when I can hit the driving range at 8 PM and loathe the part where its dark before my work day ends.

Another Nick, Alexandria VA
November 4, 2013 9:17am

"The cows didn't know about DLS and kept coming in at sunrise, but the milk tanker would arrive an hour later than usual."

Everything happens an hour sooner during daylight savings time, not an hour later. Sounds like the farmer was complaining about standard time.

Ted, Los Angeles
March 4, 2014 5:16pm

I'm not so sure about the increased A/C usage argument. Maybe it would benefit the homeowner if nobody was home and the A/C was set back but I have my doubts that this is significant. Also, by the same reasoning that says the A/C cost would be higher at home they should in turn be lower at the workplace or school where the people go for the day. My guess is it's a wash.

Mike, St. Louis
March 9, 2014 5:43pm

The money explanation doesn't work either, for all the reasons the others don't. People will be out and about the exact same number of hours regardless. No one is golfing after work, daylight savings or not. Who are these people with enough time and money to golf after work? The tiny fraction that have that kind of disposable income AND time to do it, don't need us to designate the hour of their work to make it happen. And with more and more activities being indoors, even that tiny minority is shrinking away. You bowl, shop, bar hop, see a movie, attend a concert, the amusement park, whatever, at any time they're open. If you live in the northeastern part of our country, you aren't seeing daylight no matter which way you adjust the clock. Moving it from early dark to late dark makes zero difference. Outdoor activities... that's what the weekend is for. Nor do I notice people going out less because it's dark. When we needed to adjust PT to account for extreme heat (GA) or extreme cold (NY) the 1SG just told us to come in an hour or two later or earlier. No reason to change your clocks. People are really that stupid? Old habits die hard, I guess.

Pamela Wright, watertown, NY
March 9, 2014 5:44pm

I believe the sole function of the Daylight Saving/Standard Time changes is to irritate me twice a year.

Swampwitch, Gainesville Fl
March 10, 2014 2:24pm

It's all for the golfers. So they can play longer daylight hours.

Mina Street, Baltimore, MD
March 12, 2014 1:10pm

I hate setting the clocks forward, but I love setting them back. Nothing you do in Spare Hour counts.

Andrea L, Sydney
March 27, 2014 6:12am

This article reminded me of a story I read back in a 1986 issue of Readers Digest where an old lady in Arizona was complaining about the extra month of daylight savings time the USA had recently adopted by arguing that the "extra hour of sunlight every day would damage her beloved flower garden".
- Kenneth Kowalsky, New Jersey, USA

And I'm afraid that extra hour of sunlight will scorch the crops and contribute to global warming.
;)

SORRY, I just couldn't help it!

Ron, Calgary Alberta Canada
April 15, 2014 8:09am

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