Probing Question: Why do we have Daylight Saving Time?

March 15, 2011
face of sundial surrounded by autumn leaves

Crack open Bartlett's Familiar Quotations, and you'll find hundreds of quotes and quips about the concept of time. Some celebrate bygone days, or lament lost youth, and many advise us to enjoy every minute, as in the Robert Herrick poem which opens, "Gather ye rosebuds while ye may, old Time is still a-flying."

While time itself is beyond our control, clocks and calendars are manmade constructs—and, as most Americans are reminded each spring and fall, time can be tampered with.

But why do we "fall back" and "spring ahead" at all?

Explains Jon Nese, a senior lecturer in meteorology at Penn State, "The modern idea of Daylight Saving Time, or DST, was first proposed in the 1890s in two papers published by a New Zealand entomologist, G.V. Hudson, who apparently appreciated the value of after-hours daylight for his insect-collecting habits."

A decade later, an Englishman named William Willet independently lobbied for DST in Britain. "His idea came before the House of Commons in 1908, but it was never made law," notes Nese.

For seven months during World War I, the United States adopted Daylight Saving Time under the premise of conserving electricity. Says Nese, "Franklin Roosevelt brought DST back in 1942 and called it 'War Time'—it ran year-round for three years. For two decades after the war, states were free to choose if and when to observe DST. Then, in 1966, Congress passed the Uniform Time Act, establishing a start and end date for Daylight Saving Time but allowing states and localities to decide whether to use it."

And some places do opt out, he adds. "Hawaii and most of Arizona stay on Standard Time year-round, as do U.S. territories such as Puerto Rico, the Virgin Islands, and Guam. Arizona's legislature enacted an exemption statute in 1968 and the state has not observed Daylight Time since. In places such as Hawaii and Puerto Rico, the daylight hours are similar in most seasons because of the latitude, so there's not much need for adjusting the clocks."

Does a need really exist anywhere else?

"Depends on who you talk to," says Nese. "For instance, DST has been a small challenge for Arizona businesses that operate across state lines, given that they must occasionally remind customers that Arizona does not observe DST." And contrary to the notion that DST is a boon to agriculture, "Most farmers have long opposed Daylight Saving Time because it disrupts their schedules," he says. "However, retail stores and businesses generally love DST simply because Americans tend to spend money when they have an extra hour of daylight after work," Nese explains. "In 1986, for example, the golf industry told Congress that one additional month of DST could be worth up to $400 million in extra fees and sales."

Some opponents of Daylight Saving Time say that the policy sets us up for sleep disturbances, lost productivity, and more severe auto accidents during the period when people are adapting to the time change. So far, the data are inconclusive on these points. However, research refuting DST's main rationale—energy savings—is more compelling.

In 2008, economists at the University of California at Santa Barbara, conducted an energy-use study in southern Indiana considered a "natural experiment" because most counties in the Hoosier state didn't adopt DST until 2006. (Until then, Indiana farmers had prevailed upon the state not to change its clocks.)

The study concluded that the move away from Standard Time to DST costs Indiana households an additional $8.6 million in electricity bills. It turns out that, while we may use less indoor lighting when we have longer afternoon daylight hours, we offset any savings with increased air-conditioning and heating costs on hot afternoons and cool mornings. The study also estimated that the social costs of increased pollution emissions ranged from $1.6 to $5.3 million per year. "I've never had a paper with such a clear and unambiguous finding as this," said Matthew Kotchen, one of the paper's authors, when he presented his findings at a National Bureau of Economic Research conference.

Clarifies Nese, "The original 'energy saving' argument for DST was that when there's less time between sunset and bedtime, we'll use less electricity in the evening. But Daylight Saving Time tends to push people outside in the evening, perhaps to take in a ballgame or grab some ice cream. And they typically drive to these activities. So there may be energy saving at home where the lights are off, but gasoline consumption goes up."

Pro or con, one thing is clear: lawmakers can't stop tinkering with the controversial program. In 1986, the start date was moved from the last Sunday of April to the first Sunday. In 2007, the start date was moved up three more weeks, and the end pushed back one week to the first Sunday in November.

Will DST stand the test of time? The habit of "springing forward" and "falling back" may be deeply rooted in the North American character, suggested the Canadian author Robertson Davies in his 1947 novel, The Diary of Samuel Marchbanks. "At the back of the Daylight Saving scheme," says the protagonist, "I detect the bony, blue-fingered hand of Puritanism, eager to push people into bed earlier, and get them up earlier, to make them healthy, wealthy and wise in spite of themselves."

Jon Michael Nese, Ph.D., is a Senior Lecturer in Meteorology and a Weather World host, feature writer and producer. He can be reached at

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Last Updated March 15, 2011