(This is a Repost from October, 2020)

How Does Daylight Saving Time Work?
Johnna Kaplan
Although we dutifully adjust our lives for it twice a year, the whole “Spring forward, fall back” phenomenon can be puzzling. For many people, when the time change approaches in spring or fall, it brings with it at least a moment of confusion: How does daylight saving time work, again? What day do we do this, and what time exactly do we change our clocks? Are we gaining an hour, or losing one? If that hour is truly lost, where does it go? And is it Daylight Saving or Daylight Savings Time?
That last one’s easy. Strange as it sounds if you usually say the “s,” the proper name is Daylight Saving Time. As for the rest of it, here are the facts you need to know about springing forward and falling back.

Why Does Daylight Saving Time Exist?
The first person known to have suggested a seasonal adjustment of time was none other than Benjamin Franklin. In 1784, he noted that sleeping in despite the sun’s rising earlier in the summer was a waste of good daylight. He suggested, humorously, not a nationwide changing of clocks but rather a volley of early morning cannon fire to rouse people from their beds. Several other innovators around the world had similar ideas over the next century. Some proposed more serious plans to do something about it, but ultimately these were seen as impractical and unwelcome.

The urgent need to conserve fuel during World War I finally made 31 nations implement a version of Daylight Saving Time or DST. After the war was over, most of them returned to “normal,” but soon enough World War II began. Then, 52 countries adopted the energy-saving schedule adjustment. Some changed their clocks for the whole year, including the United States. The U.S. remained on what was then called “wartime” from 1942 to 1945. (Daylight Saving Time would be extended again during the oil crisis of the 1970s.) After the war, when mandatory nationwide “wartime” ended, clock-related matters were left to state and local governments to regulate (or not) as they chose.
The federal government didn’t attempt to standardize the process again until 1966. It enacted the Uniform Time Act and established dates and times for those areas choosing to change their clocks. Further adjustments were made in 1986 and 2007. Today most people in the U.S. change their clocks at the agreed-upon time and date twice a year.