Every March, most states switch to daylight savings time. Clocks are adjusted one hour forward so the sun seems to rise and set an hour later. Each November, clocks are reset back an hour.
In latitudes outside of the tropics, the length of the day varies significantly between summer and winter, especially as one moves farther away from the equator. The reason this happens is Earth is tilted on its axis while in orbit around the sun, which means days are longer during summer and shorter in winter. In winter, the sun rises later and sets early while in summer the opposite occurs. By moving clocks forward in spring and back again in autumn, it's possible to make better use of summer daylight hours. In the U.S., clocks are adjusted at 2 a.m. local time in early March.
Who Observes Daylight Savings Time?
Most U.S. states and virtually all European countries observe daylight savings time. Hawaii doesn't switch to summer time because, being closer to the equator, there's little benefit. In Arizona, it's not observed because summer days are so hot and residents prefer the cooler evenings. Canada follows the switch, with one or two regional exceptions. Russia stopped observing daylight savings, or summer, time in 2014.
When Was It Introduced?
The first person to suggest daylight savings time was George Hudson in New Zealand in 1895. This was so he could have more time after work to enjoy the sun. In Britain, Winston Churchill and Sir Arthur Conan Doyle later supported the idea but nothing came of it. The first country to adopt daylight saving was Germany in 1916 during the First World War. Most of Europe and the United States followed suit.
After the war, the U.S. dropped daylight savings, although it was again introduced during the Second World War. When the war ended, each local authority was free to do what it wanted, but this led to a chaotic situation. In 1966, the Uniform Time Act was passed that ruled there had to be uniformity within each state. Finally, daylight savings was reintroduced as part of the Energy Policy Act of 2005.
Why Was Daylight Savings Established?
When Germany adopted daylight savings in 1916, the motivation was to save energy, primarily used for heating and lighting. This was also why it spread to other countries, and the reason it was brought back during the Second World War and in 2005. However, there is little evidence that daylight savings now actually saves energy. While this may once have been the case when lighting was less efficient, it seems any savings now achieved are more than offset by air conditioning costs.
Given that energy savings are minimal at best, the primary benefit of daylight saving is more usable daylight hours. Most people living in the northern hemisphere appreciate the fact that they can enjoy extra daylight after work, which allows them to participate in recreational activities. In the southern hemisphere, it's only Chile, Namibia, New Zealand, part of Brazil and New South Wales in Australia that bother with it.
Not everyone likes daylight savings time. Farmers don't like it because it means they have to get up in the dark to get their products to market in time. Also, there are some who feel the change disrupts our natural internal clocks. Airlines don't like it because of disruption to their schedules while TV executives see their viewership dwindle in summer.