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Daylight Saving Time: When It Happens, and Why We Do It

By Michele Berger
Published: March 7, 2014

Are you ready to spring ahead? Daylight Saving Time (DST) begins this Sunday, March 9 at 2 a.m., which means our clocks move forward one hour. The bummer part is we lose an hour of sleep that night, but on the plus side, the days stay lighter longer — a sure-fire sign that spring is just around the corner.

Benjamin Franklin gets the credit for coming up with Daylight Saving Time, according to Fred Espenak of NASA’s Goddard Space Flight Center. “The basic idea is to make the best use of daylight hours by shifting the clock forward in the spring and backward in the fall,” he wrote.

Official timekeeper for the United States, the National Institute of Standards and Technology, puts it another way: Going from Standard Time to DST, which happens during spring, essentially moves an hour of daylight from morning to night. The reverse happens in autumn, NIST writes. “The transition [back] from DST to ST effectively moves one hour of daylight from the evening to the morning.”

After World War I, the practice of moving clocks began, and in the mid-1960s, President Lyndon Johnson signed a law for when DST would start and end, making its duration from the final Sunday in April to the final Sunday of October. In 2007, a new law by the Bush Administration extended DST by a month, starting it in March instead of April. (That makes it DST about 65 percent of the calendar year, according to NIST.)

The funny part about DST is that not every state follows it. States can opt out by passing a law, Espenak notes, and a couple have done so. Currently, Hawaii and Arizona (except in Navajo Indian territories) don’t change their clocks, nor do American Samoa, Guam, Puerto Rico or the Virgin Islands. This year, Idaho also wants out, with one lawmaker introducing a bill that would exempt the state from DST.

According to one poll, many Americans don’t think DST is worth the hassle or that it saves any energy — one of the main arguments for the switch seven years ago. Here’s a proposal from Quartz magazine to do away with the practice altogether, and instead divide the U.S. into just two time zones an hour apart. Here’s another from Universe Today, which covers space and is touting the hashtag #DownWithDST.

For now, at least, it’s here to stay. Don’t forget to adjust your clocks. 

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