Clocks "fall back" this Sunday, November 3, and people are again asking: Why do we bother with daylight saving time?

The latest Rasmussen Report from March 2013 found that only 37 percent of Americans surveyed thought daylight saving time (DST) is "worth the hassle," while 45 percent said it was not.

Tufts University professor Michael Downing, author of Spring Forward: The Annual Madness of Daylight Saving Time, said such opposition has been around for a century.

"The whole proposition that you can gain or lose an hour is at best theoretical," he said. "So I think from the start people had no clear idea what we were doing or why we were doing it. It just generates confusion, and confusion generates bad will."

Beyond simple confusion and inconvenience, opponents make many cases against continuing to observe daylight saving time. (Related: "Daylight Saving Time 2013: When Does it End? And Why?")

Daylight Saving Time 101 Learn about how daylight saving time has both benefits and negative consequences.



No Energy Savings

From the early, humorous musings of Benjamin Franklin to the first widespread implementation of daylight savings during World War I and into the present day, observing DST has had a foundation in energy savings.

Lighter evenings mean lower demand for illumination and electricity, the theory goes. But studies question whether daylight saving time produces any gains at all—and some suggest it may have the opposite effect.

Indiana, once home to counties that both did and did not observe DST, adopted the practice statewide in 2006.

That unusual event meant Matthew Kotchen, an environmental economist at Yale, and colleagues could compare before-and-after electricity use across the state.

In their 2008 National Bureau of Economic Research study, the team found that lighting demand dropped, but the warmer hour of extra daylight tacked onto each evening led to more air-conditioning use, which canceled out the gains from reduced lighting and then some: Hoosiers paid higher electric bills than before DST, the study showed. (Related: "Extended Daylight Saving Time Not an Energy Saver?")

During the 2000 Sydney Olympics, parts of Australia extended daylight saving time while others did not.

Environmental economist Hendrik Wolff, of the University of Washington, and colleagues found that the practice did indeed drop lighting and electricity use in the evenings—but that higher energy demands during darker mornings completely canceled out the evening gains.

Wolff found regional differences in DST energy impacts, but paints an overall picture that's not positive.

"Everywhere there is air conditioning, our evidence suggests that daylight saving is a loser," Wolff said.

"If you don't have air conditioning, it could be a slight energy winner, but not overall in the United States. In 2007 we extended DST by one month in the U.S., and in that one month it turned out to be basically a zero-impact event." (See "Six Stealthy Energy Hogs: Are They Lurking in Your Home?")

In terms of energy savings, Downing said, Wolff's and other studies are no longer in much dispute: It's clear that DST doesn't save energy in the big picture.

Part of the story that is often ignored, he added, is the energy required to get people from place to place—gasoline. In fact the petroleum and automobile industries have always been huge supporters of DST, Downing said.

"When you give Americans more light at the end of the day, they really do want to get out of the house. And they go to ballparks, or to the mall and other places, but they don't walk there. Daylight saving reliably increases the amount of driving that Americans do, and gasoline consumption tracks up with daylight saving."

Hazardous to Your Health?

Shifting our clocks an hour naturally makes for a few groggy mornings, but some research suggests a far more dangerous impact to our bodies—an increased risk of heart attack. A 2012 study by University of Alabama at Birmingham's Martin Young found that the risk of heart attack surges by 10 percent on the Monday and Tuesday after moving the clocks ahead an hour each spring.

"Exactly why this happens is not known but there are several theories," Young said in a statement accompanying the study.

"Sleep deprivation, the body's circadian clock, and immune responses all can come into play when considering reasons that changing the time by an hour can be detrimental to someone's health."

The research reinforces 2008 findings published in the New England Journal of Medicine showing that in Sweden, heart-attack risk rose just after the spring time change.

"The most likely explanation to our findings are disturbed sleep and disruption of biological rhythms," lead author Imre Janszky, of the Norwegian University of Science and Technology, told National Geographic News in 2010.

Fortunately, these scary statistics may be balanced by the return to standard time, according to Young's research, which also found that heart-attack risk decreases 10 percent when clocks fall back.

"Just Plain Tired"

Till Roenneberg, a chronobiologist at Ludwig-Maximilians University in Munich, Germany, studies less dramatic but cumulative and possibly critical impacts to our body's natural relationship with light and dark.

His research suggests that the human body's circadian clock, kept in tune by light and darkness, never adjusts to the changing chronology of DST. (Also see "Jet Lag Cure for Mice Illuminates Inner Workings of Circadian Clocks.")

"The consequence of that is that the majority of the population has drastically decreased productivity, decreased quality of life, increasing susceptibility to illness, and is just plain tired," Roenneberg told National Geographic in 2010.

Shifting a daylight hour from morning to evening only increases "social jet lag," Roenneberg explained, in which people's actual sleeping schedule is out of whack with optimal circadian sleep periods, making them chronically tired. (See: "Leap Year: How the World Makes Up for Lost Time.")

"Light doesn't do the same things to the body in the morning and the evening. More light in the morning would advance the body clock, and that would be good. But more light in the evening would even further delay the body clock."

Our health may benefit, however, from a quantifiable boost in recreational activities that goes along with lighter evenings. Hendrik Wolff and colleagues were among several groups to document this phenomenon, in their case using data from a nationwide American time-use study.

"We found that during the period of the 2007 [daylight] extension, people engaged in more outdoor recreation and less indoor-TV watching," he said. "An additional 3 percent of people engaged in outdoor behaviors who otherwise would have stayed indoors."

Cash is king, and economics have always played a role in the politics of daylight saving time. Over the past 50 years, DST has been stretched from six months to seven months to now eight months in part because several industries have been huge supporters. In the mid-1980s, for example, the golf industry estimated that an extra month of DST was worth $200 to $400 million.

During that same time the U.S. barbecue industry pegged their increased profits at $150 million for that same additional month.

Farmers Against DST

With any controversial subject, there are sure to be groups for and against. In the case of daylight saving time, it's often difficult to sort out which are which.

For some reason, many Americans grew up believing that the practice was adopted for farmers, Downing said.

"That's the complete inverse of what's true," he said. "The farmers were the only organized lobby against daylight saving in the history of the country," he said, explaining that the practice left them with an hour less sunlight to get crops to market.

"The farmers were the reason we never had a peacetime daylight saving time until 1966. They had a powerful lobby and were against it vociferously."

Many farmers still don't like DST, including some dairy farmers, who find that cows' natural milking schedules don't adapt easily to a sudden shift.

Religious, TV Opposition

Downing noted that a number of religions with prayer times depending on sunrise or sunset also object to DST because they don't like to have holy days fooled with—particularly among Orthodox practitioners.

"That echoes the original objections with daylight saving," he said. "The idea that we were fooling around with God's time and this was the mechanized world's way of somehow taking over God's world.

"Another group that's traditionally been opposed to it are organizations like the PTA and people concerned with schoolchildren," Downing noted.

"It has been expanded by a month every 20 years or so since the mid-1960s, and now we start to get daylight saving time in the late winter/early spring and in the very late autumn. This means that our sunrise times are so late that schoolchildren are out on dark streets in the morning, and that raises objections among parents of schoolchildren."

Downing's research also suggests that studies of increased traffic accidents and injuries, which variously support or condemn the practice of daylight saving time, don't really show enough of a difference to be statistically significant in a nation where more than 30,000 people are killed in traffic accidents each year.

The TV industry, Downing said, is also among the practice's opponents. "If you look at the Nielsen ratings during the first week of daylight saving, no matter when it is, even the most popular shows go down by 10 to 15 percent in viewership."

And Utah State University economist William F. Shughart II has estimated that the simple but inconvenient act of changing America's clocks and devices back and forth represents an annual $1.7 billion of lost opportunity cost.

Shughart's rough estimates were based on the average American's hourly wage and an assumption that each person spent some ten minutes changing clocks, watches, and other devices—time that could have been far more productively spent.

Daylight Saving Time Here to Stay?

The U.S. Energy Policy Act of 2005 mandated a controversial month-long extension of daylight saving time, which began in 2007. A White House petition to end DST entirely stalled earlier this year because it failed to garner the required number of signatures, and Congress isn't currently exploring ending the practice, so it seems here to stay—at least where it's observed.

Because the federal government doesn't require states or territories to observe DST, Arizona—except for residents of the Navajo Nation—Hawaii, Puerto Rico, the Virgin Islands, American Samoa, Guam, and the Northern Marianas Islands will ignore this weekend's switch.

This type of mishmash is common around the globe, creating the confusion that may be one of DST's biggest problems, according to critics. Most Asian and African nations avoid DST altogether. South America features a mix of different DST and non-DST schedules even among neighboring nations.

And while most of North America and Europe observe DST, all those nations don't change clocks at the same time, creating further discrepancies. "Every country tries to make their best switching dates based on their best beliefs," Wolff said.

Meanwhile, the passionate debate on the subject, at least, is likely to continue as it has for a century—even where facts linking DST to a given behavior are thin to nonexistent.

"Daylight saving has been credited with speeding up production in industrial plants and lessening eye-strain among school children, and it has been blamed for forcing homemakers to prepare dinner during the hottest hours of the day and browning out lawns unaccustomed to so much sunshine," Downing said.

"As you can imagine, the Congressional Record on daylight saving constitutes the great comic novel of the 20th century," he said.