This past Sunday (the morning daylight-saving started) I was at breakfast at our lodge in Patagonia and I asked our server whether Argentina had daylight-saving time so I could be sure of the correct time. She had no idea what I was talking about so I explained daylight-saving. She responded with “no, no – we don’t have anything like that and I’m sorry to say, that sounds really stupid.” True that.

The Concept Behind DST

According to Scientific American, “Benjamin Franklin is credited with conceiving the idea of daylight-saving in 1784 to conserve candles, but the U.S. did not institute it until World War I as a way to preserve resources for the war effort.”  It is widely believed that Daylight Saving Time conserves energy because it results in more sunlight during waking hours which arguably cuts down on electricity used to create artificial light. Is that true?

Does DST Actually Save Energy?

Probably not.

In 2006 Indiana instituted daylight-saving statewide for the first time. (Before then, daylight saving time confusingly was in effect in just a handful of Indiana’s counties.) Examining electricity usage and billing since the statewide change, researchers unexpectedly found that daylight-saving time led to a 1 percent overall rise in residential electricity use, costing the state an extra $9 million. Although daylight saving time reduces demand for household lighting, the researchers suggest that it increased the demand for cooling on summer evenings and heating in early spring and late fall mornings. 

Researchers got another opportunity to test the effects of DST in 2007, when daylight-saving time nationwide began three weeks earlier, and ended one week later in the fall, than previously. The California Energy Commission discovered that extending daylight time had little to no effect on energy use in the state. The observed drop in energy use of 0.2 percent fell within the statistical margin of error of 1.5 percent.

Other studies simulating energy usage both in DST and non-DST scenarios have found that DST actually increases energy usage. The greatly improved efficiency of artificial lighting has shifted how American’s consume energy – heating and cooling now account for a much bigger slice of energy consumption. So, while DST may save energy on lighting, the costs of heating homes for an additional hour on cool mornings and cooling homes during the summer for an additional evening hour tend to outweigh the benefits of saving lighting.

DST May Kill!

Interestingly, DST may have an impact on mortality. From Scientific American: “Researchers at the Karolinska Institute in Stockholm looked at heart attack rates in Sweden since 1987 and found that the number of heart attacks rose about 5% during the first weeks of DST. ” The researchers speculated that this rise may result from the disruption of sleep patterns and biological rhythms. Similarly, a 2012 University of Alabama study found that heart attacks increase by 10% on Monday and Tuesday following the shift to Daylight Saving Time. It may take as long as 3 weeks for our bodies to adjust to DST.

In addition to heart attacks, DST results in other health issues:

This study found an increase in workplace injuries following the shift to DST, and

This study found an increase in suicides in the weeks after the shift to DST.

A mitigating factor in terms of mortality is that driving in daylight is safer than driving during the dark. A RAND Corporation study found that DST results in fewer automobile accidents and pedestrian deaths. The study authors suggested having DST year-round with no shifting of the clocks.

Economic Effects

Some industries love DST and some hate it.

Retailers like DST and have consistently lobbied to protect it, thinking that there is more shopping while it is light outside. However, according to the magazine INC., “J.P. Morgan Chase & Co. found that consumer spending goes up a bit at the start of daylight savings, but it crashes another 3.5 percent in the wrong direction when it ends” and thus is a net loser economically.

Golf courses love DST, as do purveyors of other outdoor sporting activities.

Farmers do not like it as cows and other animals don’t adjust with the change in the clocks. Airlines and other transportation providers dislike it due to scheduling headaches. According to ProCon.org, “the Air Transport Association estimated that DST cost the airline industry $147 million dollars in 2007 thanks to confused time schedules with countries who do not participate in the time change.” Additionally, think of all the people who miss appointments due to confusion over changing clocks!

Finally, “William F. Shughart II, PhD, Economist at Utah State University, states that the simple act of changing clocks costs Americans $1.7 billion in lost opportunity cost based on average hourly wages, meaning that the ten or so minutes spent moving clocks, watches, and devices forward and backward could be spent on something more productive.” (from ProCon.org)