DST originated as a wartime effort during the early 20th century to conserve energy during World War I, with Germany and Austria first implementing it in 1918 (this bill also created the current time zones across the country). 

After the war, Congress ended year-round Daylight Saving Time, and it wasn’t until WWII that it was reinstated. The purpose this time around was similar to the first: to conserve energy and fuel and promote national security and defense. This instance of year-round DST ended in 1945, and the control returned to the states. 

The US Department of Defense reports that the next 20 years following WWII were confusing and chaotic for specific federal industries (airlines, delivery, media) that rely on time across multiple states, each with different time zones. It wasn’t until 1966 that Congress took back control of DST with the Uniform Time Act, which set DST in place nationwide, although the official start and end dates have been altered several times since, most recently in 2005.

Today, only two states, Arizona and Hawaii, have opted out of DST and remain on permanent standard time. The annual shift requires the time difference between North America and Europe to be temporarily shortened by one hour each fall because the dates for changing clocks vary between continents.

Despite most of the country requiring time changes twice a year, according to the Associated Press, the body’s master clock, or circadian rhythm, is set by exposure to sunlight and darkness, acting "as if the central clock were like a conductor of an orchestra." When this rhythm is regularly disrupted by time changes, each of the body's organ systems "just works a little less well," according to Jamie Zeitzer, who co-directs Stanford’s Center for Sleep and Circadian Sciences.

While gaining an hour of sleep in the fall is generally easier on the body, the spring switch, when an hour is lost, is linked to public health concerns. The Associated Press reports that the days following the springtime change "have been linked to increases in car crashes and even an uptick in heart attacks." Due to these findings, organizations like the American Medical Association and American Academy of Sleep Medicine have been advocates for the adoption of permanent standard time.

In the last 10 years, 45 states, including Minnesota, have urged Congress to make DST permanent, thus removing the need to change clocks. Congress is the only entity that can make that change. In March 2022, the Sunshine Protection Act was introduced in the US Senate and passed unanimously. However, the bill failed to advance to the House of Representatives before the session ended that year. In January 2025, another version of the Sunshine Protection Act was introduced to the Senate, where it was "read twice and referred to the Committee on Commerce, Science, and Transportation." However, no further action has been taken since then.  

A companion bill, H.R. 139, was also introduced in the House in early January 2025 and referred to the House Energy and Commerce Committee. 

Until a version of the Sunshine Protection Act (or another, similar bill) is successfully passed by both chambers and signed into law, the twice-yearly clock change remains the national standard.