Daylight saving time strikes again Sunday at 2 a.m., at least for every state outside Hawaii and Arizona. Though DST has been a part of life in the United States since World War I, its origin and effects remain misunderstood, even by some of the lawmakers responsible for it. Here are some common myths about daylight saving time.

1. Daylight saving time was meant to help farmers.

Many of us have heard that DST was developed because of farming. The idea that more daylight means more time in the field for farmers continues to get airtime on the occasional local news report and in state legislatures - "Farmers wanted it because it extends hours of working in the field," Texas state Rep. Dan Flynn offered after filing a bill that would abolish DST. Even Michael Downing, who wrote a book about DST, has said that before researching the subject, "I always thought we did it for the farmers." In fact, the inverse is true. "The farmers were the reason we never had a peacetime daylight saving time until 1966," Downing told National Geographic. "They had a powerful lobby and were against it vociferously." The lost hour of morning light meant they had to rush to get their crops to market. Dairy farmers were particularly flummoxed: Cows adjust to schedule shifts rather poorly, apparently.

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Daylight saving time, in this or any other country, was never adopted to benefit farmers; it was first proposed by William Willett to the British Parliament in 1907 as a way to take full advantage of the day's light. Germany was the first country to implement it, and the United States took up the practice upon entering World War I, hypothetically to save energy. How did farmers end up being the mythical source of DST? Downing suggests that because they were such vocal opponents, "they became associated into the popular image of daylight-saving and it got inverted on them. It was just bad luck."

2. The extra daylight makes us healthier and happier.

That additional vitamin D is good for us, right? Sen. Ed Markey, D-Mass., thinks so. "In addition to the benefits of energy savings, fewer traffic fatalities, more recreation time and increased economic activity, Daylight Saving Time helps clear away the winter blues a little earlier," he said in a statement last year. "Government analysis has proven that extra sunshine provides more than just smiles. . . . We all just feel sunnier after we set the clocks ahead." Gwyneth Paltrow agrees, opining to British Cosmopolitan in 2013: "We're human beings and the sun is the sun - how can it be bad for you? I think we should all get sun and fresh air." A little more vitamin D might be healthy, but the way DST provides it is not so beneficial to our well-being. Experts have warned about spikes in workplace accidents, suicide and headaches - just to name a few health risks - when DST starts and ends.

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One 2009 study of mine workers found a 5.7 percent increase in injuries in the week after the start of DST, which researchers thought was most likely due to disruption in the workers' sleep cycles. An examination of Australian data found a slight uptick in male suicides in the weeks following time shifts, to the effect of half an excess death per day, which the researchers blamed on the destabilizing effect of sleep disruption on people with mental health problems. And some physicians warn that changes in circadian rhythm can trigger cluster headaches, leading to days or weeks of discomfort.

The literature on these health effects is far from conclusive, but spring sunshine does not outweigh the downsides of sleep disruption across the board.

3. It helps us conserve energy.

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Congress passed the Energy Policy Act - which extended DST by a month - in 2005, ostensibly to save four more weeks' worth of energy. "An annual rite of spring, daylight saving time is also a matter of energy conservation. By having a little more natural daylight at our disposal, we can help keep daily energy costs down for families and businesses," Rep. Fred Upton, R-Mich., who co-sponsored the legislation along with Markey, said in a 2013 statement.

But in a follow-up study on the effects of the extension, the California Energy Commission found the energy savings to be a paltry 0.18 percent at best. Other studies have indicated that people may use less of some kinds of energy, such as electric lights, but more of others. More productive daylight hours might be meant to get you off the couch and recreating outside, but they're just as likely to lead to increased air-conditioner use if you stay home and gas guzzling if you don't.

A study in Indiana found a slight increase in energy use after the entire state adopted DST (for years, only some counties followed it), costing the state's residents about $9 million; the researchers believed that more air conditioning in the evening was largely to blame. That's a far cry from the $7 million that Indiana state representatives had hoped residents would save in electricity costs.

4. DST benefits businesses.

We know that businesses think daylight saving time is good for the economy - just look at who lobbied for increased DST in 2005: chambers of commerce. The grill and charcoal industries, which successfully campaigned to extend DST from six to seven months in 1986, say they gain $200 million in sales with an extra month of daylight saving. When the increase to eight months came up for a vote in 2005, it was the National Association of Convenience Stores that lobbied hardest - more time for kids to be out trick-or-treating meant more candy sales.

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But not all industries love daylight saving time. Television ratings tend to suffer during DST, and networks hate it. "Come March, when daylight savings time and the HUT 1/8households using television 3/8 level goes down in the early evening, it really takes its toll on the 8 o'clock hour, particularly for comedies," Kevin Reilly, then chairman of Fox Entertainment, said in 2014, explaining his decision to cut the network's 8 p.m. comedy hour.

Airlines have also complained loudly about increased DST. When DST was lengthened, the Air Transport Association estimated that the schedule-juggling necessary to keep U.S. flights lined up with international travel would cost the industry $147 million. DST hurts other transportation interests, too: Amtrak is known to halt its overnight trains for an hour when clocks change in November so they don't show up and leave from their 3 a.m. destinations early. In the spring, trains have to try to make up lost time so they can stick to the schedule.

DST might also cost employers in the form of lost productivity. A 2012 study found that workers were more likely to cyberloaf - doing non-work-related things on their computers during the day - on the Monday after a DST switch. Study participants who lost an hour of sleep ended up wasting 20 percent of their time.

5. Standard time is standard.

Guess what time we're on for eight months of the year? Daylight saving time. In what universe is something that happens for only one-third of the time the "standard"? Even before the 2007 change, DST ran for seven months out of 12.

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In fact, some opponents of DST aren't against daylight saving time per se: They think it should be adopted as the year-round standard time. Because it basically already is.

Feltman anchors the blog Speaking of Science at The Washington Post.