DST is a legislative creation. The first country to broadly implement DST was Germany: in 1916, Germany introduced DST to cut down on the use of artificial lighting and to save energy during World War I. Other countries involved in the war soon followed suit, although they returned to standard time after the war. In the United States, DST was signed into law by President Lyndon Johnson in 1966, creating a 6-month period that moved clocks ahead by 1 hour across the country. That period was extended twice, once in 1986 and again in 2005, when a new energy policy increased DST by 4 weeks.
However, DST has attracted its share of criticism. DST can adversely affect your health: studies have suggested that DST leads to a significant uptick in strokes and heart attacks in the days immediately following the time change in the spring. Aside from the potential health impact, DST may not offer any economic benefits and may in fact be harmful. Although DST was meant to curtail energy use, it may increase energy consumption, especially during summer months when people may run their air conditioning during the extended daylight hours.
Because DST is a legislative creation, states may opt out by passing laws. As of 2017, only two states (Arizona and Hawaii) had passed laws opting out of DST, although another 16 states were considering laws that would alter DST. In early 2018, Florida made a bid to join the short list of states that do not change their clocks. The “Sunshine Protection Act,” signed into law by Governor Rick Scott, would establish year-round DST, provided that Congress passes legislation approving the change. California also recently approved a ballot measure in favor of repealing clock change and establishing year-round DST. To become law, the measure must be approved by a two-thirds majority of the state legislature and by Congress. These changes may introduce more time zones within the United States and require greater coordination on matters like travel and business.