It's a twice-yearly ritual for almost every American: moving the clocks ahead one hour onto daylight-saving time in the spring, then back again to standard time in the fall. But the big question is, "Why?"
"20/20" conducted an informal poll on a city street, and most of the people we spoke to thought daylight-saving time had something to do with agriculture.
One man said, "I think it started in the 19th century so the farmers would have more time to work on the fields."
A second passerby agreed, adding that "it gives them extra time to plant, extra time to harvest."
Is there any truth to that common belief? Several farmers were surprised to hear what the city folk had to say.
'Farmers Don't Like Change'
Pearce and Alice McKinney, sheep farmers in Indiana, said they don't use an alarm clock to wake up each morning. Getting up before dawn just comes naturally and no matter what the clock says, feeding time is feeding time for their animals.
According to Pearce McKinney, "This lifestyle dictates that you maintain them before you maintain yourselves. And with that in mind, clocks don't have a bearing on it."
In fact, many farmers don't like when the clocks change. Indiana recently became one of the last states to fully observe daylight-saving time after years of resistance by farmers who had lobbied against it.
"We did fight pretty hard not to have it," said Jim Benham, the president of the Indiana Farmers Union. "I know of no farm activities that benefit from having [daylight-saving time]."
Both Benham and Pearce McKinney agree on the reason for farmers' resistance. "You must understand, farmers don't like change," said McKinney.
So it's a myth that we follow daylight-saving time to help out the farmers. The real reason Congress decided to change the clocks is to save energy, but could that also be a myth?
It's an idea that dates all the way back to Benjamin Franklin.
Living in Paris in 1784, he wrote an essay jokingly suggesting that moving the hour of sunlight from the morning, when Parisians tend to be sleeping anyway, to the evening could save millions of candles.
"An immense sum that the city of Paris might save every year, by the economy of using sunshine instead of candles." Click here to read the entire essay.
The United States first adopted daylight-saving time in 1918 to save energy during World War I, then again for three years during World War II.
In the years following, there was no national policy, so states and counties were free to turn the clock back on their own. Confusion followed, leading Congress to finally pass the Uniform Time Act of 1966, which created daylight-saving time from the last Sunday in April through the last Sunday in October.
States could opt out if they liked, and several did -- including Arizona and Hawaii, which still don't follow daylight-saving time today.
Daylight-Saving Time Energy Efficient?
During the Arab oil embargo in the 1970s, the United States temporarily extended daylight-saving time year-round.
The Department of Transportation was asked to study the results and released a report in 1975 that concluded that it was possible that 100,000 barrels of oil may have been saved by extending daylight-saving time by two months -- about 1 percent of the use at that time.
But the report also noted that "the potential benefits are small and difficult to isolate from the larger effects of seasonal variations and of changes in energy availability and prices."
It goes on to say that the findings "do not provide conclusive support for recommending permanent changes to [daylight-saving time]." Further study was suggested.
Despite that less-than-stellar finding, Congress relied on the Department of Transportation study in 1986, when it voted to move the start of daylight-saving time to the first Sunday in April, and again in 2005 when it moved the start back another month.
Congressman Ed Markey, D-Mass., who co-sponsored both bills, says that he's sure that daylight-saving time saves energy -- if even just a little -- noting that it is "not the solution in and of itself to an energy crisis, to global warming, but it's a little part of it. Not a silver bullet but enough of an addition, that it's worthwhile."
But two newer studies found the opposite to be true. During the 2000 Olympics, Australia temporarily lengthened daylight-saving time, and researchers found that slightly more electricity was used as a result.
Meanwhile in Indiana, the state legislature voted to put the entire state on daylight-saving time for the first time in 2006. That resulted in a unique opportunity to compare power use by homeowners before and after it was introduced.
Matthew Kotchen studied the data and was surprised to find that residential use went up.
"Over the whole daylight-saving time period," Kotchen said, "residential electricity increased between 1 [percent] to 4 percent."
The reason why, he speculates, is that "in the spring, in the fall, when the days are relatively shorter and colder, you're making people wake up at the darkest, coldest time of day, early in the morning."
So we may end up running heat longer. And moving an hour of sunlight to summer evenings means an extra hour of air conditioning. Click here to read the working paper.
Critics noted that the study only looked at residential power use, not the much larger commercial power usage -- although Kotchen contends this is more stable and less likely to change because of personal habits.
Markey responded that "one study of the situation in Indiana cannot accurately assess the impact of [daylight-saving time] changes across the nation, especially when it does not include more northern, colder regions."
The debate will be fueled further in late June, when the Department of Energy releases a new study looking at the effect of the recent lengthening of daylight-saving time.
In the meantime, Markey points out that there are other benefits to moving the hour of sunlight to the evenings.
In fact, the 1975 government study also reported a 10 percent to 13 percent reduction in violent crime for daylight-saving time periods in Washington, D.C.
Transportation officials did, however, caution that the study should not be viewed as conclusive evidence that daylight-saving time reduced crime, especially given both the limited time and limited sample area. Others point out that it just makes sense that criminals are less likely to commit crimes in the daylight.
Another key benefit cited by the 1975 study was a reduction in traffic deaths. In the years since then, several other studies have supported the traffic safety angle, finding that fewer pedestrians are killed each year by cars, possibly because of the evening light provided by daylight-saving time.
Markey points to all this, as well as the immeasurable benefit of family time outdoors in the evening.
"Even if it didn't save energy, which it does," he said, "it still lets people have the hour in the evening. It still reduces the crime rate. It still reduces the number of accidents on the highway. It still makes it possible for people with night blindness to have an extra hour in the evening when they can walk around. And it still brings a smile to people's faces."
And now that they lost their battle with the clock, the Indiana farmers seem to agree. The Indiana Farmers Union's Benham said, "To be honest with you, after we had it for a week or so, it wasn't too bad a deal."