At 2 a.m. on Sunday, Nov. 5, clocks in most of the United States will “fall back” one hour, ending daylight saving time for the year. Although this process has become as smooth a clockwork for many, daylight saving time has had an interesting and chaotic history.
The idea of daylight saving time was first proposed by George Hudson of New Zealand in 1895, according to the Library of Congress. A postal worker by day, Hudson enjoyed studying and observing insects, and did most of this work in the evenings. He wrote up the idea in a paper presented to Wellington Philosophical Society, but New Zealand didn’t start daylight saving time until 1927.
The U.S. began using daylight saving time during World War I, and then again during World War II. Between 1945 and 1966 some states observed daylight saving and some didn’t, until Congress passed the Uniform Time Act to establish a federal standard for when the clocks would change.
Sometimes referred to as daylight savings time, in the U.S. the official name is daylight saving time, according to the U.S. Government Publishing Office.
The period that is not daylight saving time, lasting from November to March, is formally known as standard time. In Europe, daylight saving time is known as summer time.
Because some areas do not observe daylight saving time, mainland Australia’s three time zones become five time zones during daylight saving time, resulting in a one and a half hour time shift when crossing from Western Australia to South Australia, according to information from the Australian government.
An island off the coast of Australia changes its clocks by 30 minutes. Lord Howe Island has a half time zone, 30 minutes off of its neighboring time zones, but during daylight savings time, the clocks on the island move 30 minutes forward, joining the rest of the state of New South Wales in its time zone.
The length of daylight saving was extended by U.S. Congress in 1986, and again in 2005. The National Association of Convenience Stores estimates that the first extension led to an increase of $1 billion in convenience store sales per year at the time.
Most countries near the equator do not observe daylight saving time, because daylight hours do not change much in those areas of the world, according to the National Sleep Foundation. About 70 percent of countries observe some form of daylight saving.
In 1973, President Richard Nixon signed the Emergency Daylight Saving Time Energy Conservation Act, which temporarily put the U.S. on year-round daylight saving time in response to the oil embargo, according to the Congressional Research Service. Although the trial period was supposed to last until April of 1975, the bill was later amended to end daylight saving in October of 1974.
While in the U.S., clocks change at 2 a.m. local time in each time zone, countries in the European Union switch their clocks simultaneously, resulting in changes at a different local time in each time zone, according to info from the EU. The union set common dates for clock changes in 1981 to avoid confusion between countries.
In 2011, Russia switched to permanent daylight saving time, setting their clocks ahead one hour in the spring and keeping them there, according to Time and Date AS. The plan was unpopular, with members of parliament blaming an increase in traffic accidents on time-related stress. Russia abolished daylight saving time in 2014, setting their clocks back one hour permanently.
Until 2006, daylight saving time was decided on a county-by-county basis in Indiana, which — in addition to the state’s multiple time zones — resulted in confusion, according to Time and Date AS.
According to studies conducted by the U.S. Department to Energy, the energy savings related to daylight saving time are relatively small. The 2008 study found that the energy savings were equivalent to 0.03 percent of U.S, electricity consumption per year.
Time changes may be potentially harmful, according to information from the Centers for Disease Control and Prevention. A 2015 study found that the body needs about one week to adjust and get back into a normal sleep schedule after the clock changes for daylight saving, and a 2015 study found that people with heart disease may be at higher risk for a heart attack the week after the time changes.