Daylight Saving

Brian Handwerk

for National Geographic News

Updated March 13, 2011

With daylight saving time (also called daylight savings time) kicking off again, clock confusion is once again ticking away: Why do we spring forward? Does daylight saving time really save energy? Is it bad for your health? Get expert answers below.

When Did Daylight Savings Begin in 2011?

For most Americans, daylight saving time 2011 started at 2 a.m. on Sunday, March 13, when most states sprang forward an hour. Time will fall back to standard time again on Sunday, November 6, 2011, when daylight saving time ends.

The federal government doesn't require U.S. states or territories to observe daylight saving time, which is why residents of Arizona, Hawaii, Puerto Rico, the Virgin Islands, American Samoa, Guam, and the Northern Marianas Islands won't need to change their clocks this weekend.

Where it is observed, daylight savings has been known to cause some problems.

National surveys by Rasmussen Reports, for example, show that 83 percent of respondents knew when to move their clocks ahead in spring 2010. Twenty-seven percent, though, admitted they'd been an hour early or late at least once in their lives because they hadn't changed their clocks correctly.

It's enough to make you wonder—why do we do use daylight saving time in the first place?

How and When Did Daylight Saving Time Start?

Ben Franklin—of "early to bed and early to rise" fame—was apparently the first person to suggest the concept of daylight savings, according to computer scientistDavid Prerau, author of the book Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time.

While serving as U.S. ambassador to France in Paris, Franklin wrote of being awakened at 6 a.m. and realizing, to his surprise, that the sun would rise far earlier than he usually did. Imagine the resources that might be saved if he and others rose before noon and burned less midnight oil, Franklin, tongue half in cheek, wrote to a newspaper.

"Franklin seriously realized it would be beneficial to make better use of daylight but he didn't really know how to implement it," Prerau said.

It wasn't until World War I that daylight savings were realized on a grand scale. Germany was the first state to adopt the time changes, to reduce artificial lighting and thereby save coal for the war effort. Friends and foes soon followed suit.

In the U.S. a federal law standardized the yearly start and end of daylight saving time in 1918—for the states that chose to observe it.

During World War II the U.S. made daylight saving time mandatory for the whole country, as a way to save wartime resources. Between February 9, 1942, and September 30, 1945, the government took it a step further. During this period daylight saving time was observed year-round, essentially making it the new standard time, if only for a few years.

Since the end of World War II, though, daylight saving time has always been optional for U.S. states. But its beginning and end have shifted—and occasionally disappeared.

During the 1973-74 Arab oil embargo, the U.S. once again extended daylight saving time through the winter, resulting in a one percent decrease in the country's electrical load, according to federal studies cited by Prerau.

Thirty years later the Energy Policy Act of 2005 was enacted, mandating a controversial monthlong extension of daylight saving time, starting in 2007.

But does daylight saving time really save any energy?

Daylight Saving Time: Energy Saver or Just Time Suck?

In recent years several studies have suggested that daylight saving time doesn't actually save energy—and might even result in a net loss.

Environmental economist Hendrik Wolff, of the University of Washington, co-authored a paper that studied Australian power-use data when parts of the country extended daylight saving time for the 2000 Sydney Olympics and others did not. The researchers found that the practice reduced lighting and electricity consumption in the evening but increased energy use in the now dark mornings—wiping out the evening gains.

Likewise, Matthew Kotchen, an economist at the University of California, saw inIndiana a situation ripe for study.

Prior to 2006 only 15 of the state's 92 counties observed daylight saving time. So when the whole state adopted daylight saving time, it became possible to compare before-and-after energy use. While use of artificial lights dropped, increased air-conditioning use more than offset any energy gains, according to the daylight saving time research Kotchen led for the National Bureau of Economic Research[PDF] in 2008.

That's because the extra hour that daylight saving time adds in the evening is a hotter hour. "So if people get home an hour earlier in a warmer house, they turn on their air conditioning," the University of Washington's Wolff said.

In fact, Hoosier consumers paid more on their electric bills than before they made the annual switch to daylight saving time, the study found.

(Related: "Extended Daylight Saving Time Not an Energy Saver?")

But other studies do show energy gains.

In an October 2008 daylight saving time report to Congress (PDF), mandated by the same 2005 energy act that extended daylight saving time, the U.S. Department of Energy asserted that springing forward does save energy.

Extended daylight saving time—still in practice in 2011—saved 1.3 terawatt hours of electricity. That figure suggests that daylight saving time reduces annual U.S. electricity consumption by 0.03 percent and overall energy consumption by 0.02 percent.

While those percentages seem small, they could represent significant savings because of the nation's enormous total energy use.

What's more, savings in some regions are apparently greater than in others.

California, for instance, appears to benefit most from daylight saving time—perhaps because its relatively mild weather encourages people to stay outdoors later. The Energy Department report found that daylight saving time resulted in an energy savings of one percent daily in the state.

But Wolff, one of many scholars who contributed to the federal report, suggested that the numbers were subject to statistical variability and shouldn't be taken as hard facts.

And daylight savings' energy gains in the U.S. largely depend on your location in relation to the Mason-Dixon Line, Wolff said.

"The North might be a slight winner, because the North doesn't have as much air conditioning," he said. "But the South is a definite loser in terms of energy consumption. The South has more energy consumption under daylight saving."

(See in-depth energy coverage from National Geographic News.)

Daylight Saving Time: Healthy or Harmful?

For decades advocates of daylight savings have argued that, energy savings or no, daylight saving time boosts health by encouraging active lifestyles—a claim Wolff and colleagues are currently putting to the test.

"In a nationwide American time-use study, we're clearly seeing that, at the time of daylight saving time extension in the spring, television watching is substantially reduced and outdoor behaviors like jogging, walking, or going to the park are substantially increased," Wolff said. "That's remarkable, because of course the total amount of daylight in a given day is the same."

But others warn of ill effects.

Till Roenneberg, a chronobiologist at Ludwig-Maximilians University in Munich, Germany, said his studies show that our circadian body clocks—set by light and darkness—never adjust to gaining an "extra" hour of sunlight to the end of the day during daylight saving time.

"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 said.

One reason so many people in the developed world are chronically overtired, he said, is that they suffer from "social jet lag." In other words, their optimal circadian sleep periods are out of whack with their actual sleep schedules.

Shifting daylight from morning to evening only increases this lag, he said.

"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."

Other research hints at even more serious health risks.

A 2008 study in the New England Journal of Medicine concluded that, at least in Sweden, heart attack risks go up in the days 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 Karolinska Institute's Department of Public Health Sciences in Stockholm, told National Geographic News via email.

(Related: "Leap Year: How the World Makes Up for Lost Time.")

Daylight Savings Lovers, Haters

With verdicts on the benefits, or costs, of daylight savings so split, it may be no surprise that the yearly time changes inspire polarized reactions.

In the U.K., for instance, the Lighter Later movement—part of 10:10, a group advocating cutting carbon emissions—argues for a sort of extreme daylight savings. First, they say, move standard time forward an hour, then keep observing daylight saving time as usual—adding two hours of evening daylight to what we currently consider standard time.

The folks behind Standardtime.com, on the other hand, want to abolish daylight saving time altogether. Calling energy-efficiency claims "unproven," they write: "If we are saving energy let's go year round with Daylight Saving Time. If we are not saving energy let's drop Daylight Saving Time!"

But don't most people enjoy that extra evening sun every summer? Even that remains in doubt.

National telephone surveys by Rasmussen Reports from spring 2010 and fall 2009 deliver the same answer. Most people just "don't think the time change is worth the hassle." Forty-seven percent agreed with that statement, while only 40 percent disagreed.

But Seize the Daylight author David Prerau said his research on daylight saving time suggests most people are fond of it.

"I think the first day of daylight saving time is really like the first day of spring for a lot of people," Prerau said. "It's the first time that they have some time after work to make use of the springtime weather.

"I think if you ask most people if they enjoy having an extra hour of daylight in the evening eight months a year, the response would be pretty positive."

Only In America do we burn our food in Cars

Americans should brace for higher food prices this year now that demand for corn has pushed U.S. supplies to their lowest point in 15 years.

Higher projected orders from the ethanol industry sent corn futures soaring Wednesday, as corn supplies became the latest commodity to plummet. Low levels of wheat, coffee, soybeans and other food staples have already sent prices surging on the global market.

As those reserves decline, U.S. food companies are warning of retail price increases. (Too late!)

The ethanol industry's projected corn orders this year have risen 8 percent, to 13 billion bushels, after record-high production in December and January, the Agriculture Department said Wednesday.

That means the United States will have a reserve of 675 million bushels left over in late August when this year's harvest begins. That's roughly 5 percent of all corn that will be consumed, the lowest surplus level since 1996. (if the harvest isn't hurt by weather conditions)

The price of corn affects most food products in supermarkets. It's used to feed the cattle, hogs and chickens that fill the meat aisle. It is the main ingredient in Cap'n Crunch and Doritos. Turned into corn syrup, it sweetens most soft drinks. (And we put it in gasoline to keep prices down....ha-ha-ha-ha)

The decline in reserves caused corn futures to surge, with prices rising 3 percent to settle at $6.98. Corn prices have already doubled in the last six months, rising from $3.50 a bushel to nearly $7 a bushel. Analysts expect the price increases to continue in coming months.

Major food makers and some restaurants have already said they'll be raising prices this year because they're paying more for corn, wheat, sugar, coffee and chocolate, all of which are at historically high prices. Weather, such as flooding in Australia and droughts elsewhere, has affected many crops this year.

A severe drought in China, the world's largest wheat grower, could force prices even higher. The U.N.'s food agency has warned that the drought is driving up the country's wheat prices, and now the focus is on whether China will buy more from the global market, where prices have already risen about 35 percent since mid-November.

Consumers will likely see price hikes as early as three months from now, though most of the impact won't be felt for another six months, said Scott Irwin an agriculture economics professor at the University of Illinois. Chicken prices are among the first to rise because the bird's life span is so short that higher feed costs get factored in quickly, he said. Price hikes for hogs take about a year and cattle two years, while packaged foods take six or seven months to start rising. (except that we don't factor in fuel or food into inflation, remember?)

Some food makers already began selectively raising prices within the past few quarters. (Really?!)

Those higher prices are filtering into stores. (As in present tense) Supermarkets have resisted price increases for some time, hoping to hold onto their cost-conscious customers in the tough economy. But chains such as Kroger now also say higher prices are coming.

Cereal maker Kellogg Co. said last week it plans to raise prices by 3 to 4 percentage points. Sara Lee Corp. said Tuesday that it will continue (as in past tense) its price increases as it copes with higher commodity costs. The company said the price it pays for coffee beans alone is up 60 percent compared with last year.

And J.M. Smucker Co. said Tuesday that it would raise prices again on Folgers and Dunkin Donuts coffee for the third time this year, by 10 percent on average. A large can of Folgers is already going for around $12 at many markets. (well that's probably a blessing in disguise for the fat-asses out there)

It's not just playing out in the grocery store. McDonald's Corp. said last month that it may raise prices this year as its own food tab rises. The company already raised prices in some markets, including the United Kingdom.

New Nuclear Plants Get More Expensive

By Dave Flessner, Chattanooga Times/Free Press, Tenn.

Jun. 11--At a cost of more than $6.2 billion when it was completed in 1996, TVA's Watts Bar Nuclear Plant is both the newest and most expensive nuclear reactor ever built in the United States.

But rising costs for everything from cement to steel are threatening to shatter that cost record for the next generation of nuclear power plants.

Despite streamlined licensing requirements and more advanced engineering and design, the latest projected costs for some of the next generation of nuclear reactors are double some initial estimates made five years ago.

TVA President Tom Kilgore said the rising costs of materials for nuclear reactors is causing the agency to re-examine its pursuit of new reactors. But the Tennessee Valley Authority, at this point, appears to still be committed to building more nuclear units.

"The cost of new plants are higher because concrete has gone up, steel has gone up, and other commodity prices have gone up," Mr. Kilgore said. "That causes us to pause and rethink, but frankly it's still the best option."

Critics of nuclear power wonder if the industry is still beset with the cost overruns that stalled any new U.S. nuclear reactors from being started in the past three decades.

"Once again, we're seeing the sticker shock from nuclear power," said Stephen Smith, executive director for the Southern Alliance for Clean Energy, a Knoxville group opposed to nuclear power. "What we continue to see from this industry are overly rosy estimates about construction costs to lure utilities into building nuclear. By the time they recognize what it is actually going to cost, they already have so much money sunk in a plant that they want to finish it."

The TVA, the nation's biggest government utility, in the 1970s and '80s sunk nearly $10 billion into nuclear plants that it ultimately decided to scrap when plant costs escalated and the growth in power demand slowed. But TVA officials insist they are using a different, more cost-competitive approach today toward building more nuclear units.

Unlike the 17 different reactors TVA began designing in the 1960s, the authority now is taking its power additions one reactor at a time to better align new power generation and power demand and to focus management attention on each reactor.

The next generation of reactors also will be built in cooperation with other utilities and with standardized designs to help speed construction and allow workers to successfully move from one plant to another, TVA Vice President Jack Bailey said.

"TVA is already leading the industry in additional nuclear generation," Mr. Bailey said.

After restarting TVA's oldest reactor last year through a five-year, $1.8 billion upgrade at the Browns Ferry plant near Athens, Ala., TVA is spending $2.5 billion to finish a second reactor at its Watts Bar plant by 2012.

Even more ambitious are TVA's preliminary plans for two of the next-generation nuclear reactors at its Bellefonte nuclear site in Hollywood, Ala. The reactors, to be built by Westinghouse, are expected to cost about $3 billion to $5 billion each, Mr. Bailey said.

A study three years ago jointly conducted by Toshiba Power Systems, Bechtel Corp. and TVA initially estimated the cost of each of the new AP-1000 reactors at Bellefonte at around $1,600 a kilowatt, or about $2 billion for each of the planned units.

"That is now probably bouncing around $3,500 a kilowatt, and even higher in some circumstances," said Adrian Heymer, senior director for new plant deployment at the Nuclear Energy Institute, an industry-backed trade group in Washington D.C.

Other utilities are projecting even higher costs to develop and finance similar reactors. Moody's Investors Service estimated last year that the cost of a new 1,000-megawatt reactor even smaller than what TVA wants to build at Bellefonte will cost between $5 billion and $6 billion.

Progress Energy Florida estimated that building reactors at a new 3,000-acre site in Levy County near Tampa, Fla., would cost about $7 billion per unit. Farther south near Miami, Florida Power & Light estimates the cost of adding new units at Turkey Point nuclear plant could range from $6.5 billion up to $12 billion per reactor, according to a March filing with Florida regulators.

David A. Kraft, director of the Nuclear Energy Information Service, an anti-nuclear group in Chicago, said cost estimates for new nuclear reactors continue to rise and the new designs of reactors add extra uncertainty to utility estimates.

"The upward trend in costs is unmistakable and also exists internationally," he said.

Mr. Kraft and Mr. Smith urged TVA and other utilities to take the billions of dollars they are planning to invest in new nuclear units and put it instead into aggressive efficiency measures and renewable energy generation from solar, wind and biomass.

"Nuclear plants take decades to pay off and, by that time, we can develop other sources of power like wind and solar that don't have any fuel costs and don't produce radioactive wastes," Mr. Smith said.

Mr. Bailey said higher cost estimates from other utilities reflect, in part, their desire to gain approval from state regulators to cover any unanticipated costs for the new reactors. The TVA executive noted that the Bellefonte site where TVA is proposing to build its new reactors already is developed with site security, transmission and cooling towers built for earlier reactors TVA scrapped in the 1990s.

Buying equipment in advance also could lock in costs to prevent costly increases later, he said.

Mr. Heymer said the costs of all types of generation will be higher in the future and nuclear power isn't as subject to rising fuel costs as is power generation from either coal or natural gas.

"No matter what you use to generate power, the consumer is going to see an increase in the cost of electricity," Mr. Heymer said. "Nuclear power is still competitive with other forms of generation and, if you put in the environmental concerns and new limits on carbon emissions, nuclear turns out to be the best buy."