Daylight saving time

Seasonal change of clock settings

"DST" redirects here. For other uses, see DST (disambiguation).

For the film, see Daylight Savings (film).

Daylight saving time regions:

Northern Hemisphere summer

Southern Hemisphere summer

Formerly used daylight saving

Never used daylight saving

Daylight saving time (DST), also referred to as daylight saving(s), daylight savings time, daylight time (United States and Canada), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks to make better use of the longer daylight available during summer so that darkness falls at a later clock time. The typical implementation of DST is to set clocks forward by one hour in spring or late winter, and to set clocks back by one hour to standard time in the autumn (or fall in North American English, hence the mnemonic: "spring forward and fall back").

As of 2025, polls indicate a slight majority of those polled in the United States favor abolishing DST,[1] with momentum gaining in all areas where the practice persists either to abolish DST and switch permanently to standard time,[2] or to make DST permanent. Common arguments for abolishing or making DST permanent include health risks, economic costs, lost sleep, and disruptions to daily routines.[3]

## Overview

[edit]

As of 2023, around 34 percent of the world's countries use DST.[4] Some countries observe it only in some regions. In Canada, all of Yukon, most of Saskatchewan, and parts of Nunavut, Ontario, British Columbia and Quebec do not change clocks, and use permanent DST. It is observed by four Australian states and one territory. In the United States, it is observed by all states except Hawaii and Arizona (within the latter, however, the Navajo Nation does observe it).[5]

Historically, several ancient societies adopted seasonal changes to their timekeeping to make better use of daylight; Roman timekeeping even included changes to water clocks to accommodate this. However, these were changes to the time divisions of the day rather than setting the whole clock forward. In a satirical letter to the editor of the Journal de Paris in 1784, Benjamin Franklin suggested that if Parisians could only wake up earlier in the summer they would economize on candle and oil usage, but he did not propose changing the clocks.[6][7] In 1895, New Zealand entomologist and astronomer George Hudson made the first realistic proposal to change clocks by two hours every spring to the Wellington Philosophical Society, but this was not implemented until 1928 and in another form.[8] In 1907, William Willett proposed the adoption of British Summer Time as a way to save energy; although seriously considered by Parliament, it was not implemented until 1916.[9]

The first implementation of DST was by Port Arthur (today merged into Thunder Bay), in Ontario, Canada, in 1908, but only locally, not nationally.[10][11] The first nation-wide implementations were by the German and Austro-Hungarian Empires, both starting on 30 April 1916. Since then, many countries have adopted DST at various times, particularly since the 1970s energy crisis.[citation needed]

## Rationale

[edit]

An ancient water clock that lets hour lengths vary with season

Industrialized societies usually follow a clock-based schedule for daily activities that do not change throughout the course of the year. The time of day that individuals begin and end work or school, and the coordination of mass transit, for example, usually remain constant year-round. In contrast, an agrarian society's daily routines for work and personal conduct are more likely governed by the length of daylight hours[12][13] and by solar time, which change seasonally because of the Earth's axial tilt. North and south of the tropics, daylight lasts longer in that hemisphere's summer and is shorter in that hemisphere's winter, with the effect becoming greater the farther one moves away from the equator. DST is of little use for locations near the Equator, because these regions see only a small variation in daylight over the course of the year.

After synchronously resetting all clocks in a region to one hour ahead of standard time in spring in anticipation of longer daylight hours, individuals following a clock-based schedule will be awakened an hour earlier in the solar day than they would have otherwise. They will begin and complete daily work routines an hour earlier; in most cases, they will have an extra hour of daylight available to them after their workday activities.[14][15]

The clock shift is partly motivated by practicality. At the summer solstice, in American temperate latitudes, for example, the sun rises around 04:30 standard time and sets around 19:30. Since most people are asleep at 04:30, it is seen as practical to treat 04:30 as if it were 05:30, thereby allowing people to wake closer to the sunrise and be active in the evening light, as the sun under DST sets an hour later (20:30). The longer evening daylight hours are attractive to golfers, for example, while farmers traditionally expressed dislike for having to be out working while dew is still heavy.

Proponents of daylight saving time argue that most people prefer more daylight hours after the typical "nine to five" workday.[16][17] Supporters have also argued that DST decreases energy consumption by reducing the need for lighting and heating, but the actual effect on overall energy use is heavily disputed.[18][19] For evaluation, it is required to go beyond considering only energy demand for lighting and also consider the energy used for heating or cooling buildings.[20]

### Variation within a time zone

[edit]

The effect of daylight saving time also varies according to how far east or west the location is within its time zone, with locations farther east inside the time zone benefiting more from DST than locations farther west in the same time zone.[21] Despite a width spanning thousands of kilometers, all of China is located within a single time zone per government mandate, increasing the daylight shift the farther west one is.

## History

[edit]

Ancient civilizations adjusted daily schedules to the sun more flexibly than DST does, often dividing daylight into 12 hours regardless of daytime, so that each daylight hour became progressively longer during spring and shorter during autumn.[22] For example, the Romans kept time with water clocks that had different scales for different months of the year; at Rome's latitude, the third hour from sunrise (hora tertia) started at 09:02 solar time and lasted 44 minutes at the winter solstice, but at the summer solstice it started at 06:58 and lasted 75 minutes.[23] From the 14th century onward, equal-length civil hours supplanted unequal ones, so civil time no longer varied by season. Unequal hours are still used in a few traditional settings, such as monasteries of Mount Athos[24] and in Jewish ceremonies.[25]

Benjamin Franklin published the proverb "early to bed and early to rise makes a man healthy, wealthy, and wise",[26][27] and published a letter in the Journal de Paris when he was an American envoy to France (1776–1785) suggesting that Parisians economize on candles by rising earlier to use morning sunlight.[28] This 1784 satire proposed taxing window shutters, rationing candles, and waking the public by ringing church bells and firing cannons at sunrise.[29] Despite common misconception, Franklin did not actually propose DST; 18th-century Europe did not even keep precise schedules. However, this changed as rail transport and communication networks required a standardization of clocks unknown in Franklin's day.[30]

In 1810, the Spanish National Assembly Cortes of Cádiz issued a regulation that moved certain meeting times forward by one hour from 1 May to 30 September in recognition of seasonal changes, but it did not change the clocks. It also acknowledged that private businesses were in the practice of changing their opening hours to suit daylight conditions, but they did so of their volition.[31][32]

George Hudson was the first to propose modern DST, in 1895.

New Zealand entomologist George Hudson first proposed modern DST. His shift-work job gave him spare time to collect insects and led him to value after-hours daylight.[8] In 1895, he presented a paper to the Wellington Philosophical Society proposing a two-hour daylight-saving shift,[14] and considerable interest was expressed in Christchurch; he followed up with an 1898 paper.[33] Many publications credit the DST proposal to prominent English builder and outdoorsman William Willett,[34] who independently conceived DST in 1907 during a pre-breakfast ride when he observed how many Londoners slept through a large part of a summer day.[17] Willett also was an avid golfer who disliked cutting short his round at dusk.[35] His solution was to advance the clock during the summer, and he published the proposal two years later.[36] Liberal Party member of parliament Robert Pearce took up the proposal, introducing the first Daylight Saving Bill to the British House of Commons on 12 February 1908.[37] A select committee was set up to examine the issue, but Pearce's bill did not become law and several other bills failed in the following years.[9] Willett lobbied for the proposal in the UK until his death in 1915.

DST was first implemented in the United States to conserve energy during World War I (poster by United Cigar Stores).

Port Arthur, Ontario, Canada, was the first city in the world to enact DST, on 1 July 1908.[10][11] This was followed by Orillia, Ontario, introduced by William Sword Frost while mayor from 1911 to 1912.[38] The first states to adopt DST (German: Sommerzeit) nationally were those of the German Empire and its World War I ally Austria-Hungary commencing on 30 April 1916, as a way to conserve coal during wartime. Britain, most of its allies, and many European neutrals soon followed. Russia and a few other countries waited until the next year, and the United States adopted daylight saving in 1918. Most jurisdictions abandoned DST in the years after the war ended in 1918, with exceptions including Canada, the United Kingdom, France, Ireland, and the United States.[39] It became common during World War II (some countries adopted double summer time), and was standardized in the US by federal law in 1966, and widely adopted in Europe from the 1970s as a result of the 1970s energy crisis. Since then, the world has seen many enactments, adjustments, and repeals.[40]

It is a common myth in the United States that DST was first implemented for the benefit of farmers.[41][42][43] In reality, farmers have been one of the strongest lobbying groups against DST since it was first implemented.[41][42][43] The factors that influence farming schedules, such as morning dew and dairy cattle's readiness to be milked, are ultimately dictated by the sun, so the clock change introduces unnecessary challenges.[41][43][44]

DST was first implemented in the US with the Standard Time Act of 1918, a wartime measure for seven months during World War I in the interest of adding more daylight hours to conserve energy resources.[45][44] Year-round DST, or "War Time", was implemented again during World War II.[45] After the war, local jurisdictions were free to choose if and when to observe DST until the Uniform Time Act which standardized DST in 1966.[45][46] Permanent daylight saving time was enacted for the winter of 1974, but there were complaints of children going to school in the dark and working people commuting and starting their work day in pitch darkness during the winter, and it was repealed a year later.[citation needed]

## Procedure

[edit]

See also: Daylight saving time by country

When DST observation begins, clocks are advanced by one hour during the very early morning.

When DST observation ends and standard time observation resumes, clocks are turned back one hour during the very early morning.

Specific times of the clock change vary by jurisdiction.

The relevant authorities typically schedule clock changes to occur at (or soon after) midnight and on a weekend, in order to lessen disruption to weekday schedules.[47] A one-hour change is usual, but twenty-minute and two-hour changes have been used in the past. Notable exceptions today include Lord Howe Island with a thirty-minute change, and Troll (research station) that shifts two hours directly between CEST and GMT since 2016.[48] In all countries that observe daylight saving time seasonally (i.e., during summer and not winter), the clock is advanced from standard time to daylight saving time in the spring, and it is turned back from daylight saving time to standard time in the autumn.

For a midnight change in spring, a digital display of local time would appear to jump from 23:59:59.9 to 01:00:00.0. For the same clock in autumn, the local time would appear to repeat the hour preceding midnight, i.e. it would jump from 23:59:59.9 to 23:00:00.0.

In most countries that observe seasonal daylight saving time, clocks revert in winter to standard time.[49][50] An exception exists in Ireland, where its winter clock has the same offset (UTC+00:00) and legal name as that in Britain (Greenwich Mean Time)—but while its summer clock also has the same offset as Britain's (UTC+01:00), its legal name is confusingly called Irish Standard Time[51][52] as opposed to British Summer Time.[53]

Since 2019, Morocco observes daylight saving time every month but Ramadan. During the holy month (the date of which is determined by the lunar calendar and thus moves annually with regard to the Gregorian calendar), the country's civil clocks observe Western European Time (UTC+00:00, which geographically overlaps most of the nation). At the close of that month, its clocks are turned forward to Western European Summer Time (UTC+01:00).[54][55][56]

The time at which to change clocks differs across jurisdictions. Members of the European Union conduct a coordinated change, changing all zones at the same instant, at 01:00 Coordinated Universal Time (UTC), which means that it changes at 02:00 Central European Time (CET), equivalent to 03:00 Eastern European Time (EET). As a result, the time differences across European time zones remain constant.[57][58] North America coordination of the clock change differs, in that each jurisdiction changes at each local clock's 02:00, which temporarily creates an imbalance with the next time zone (until it adjusts its clock, one hour later, at 2 am there). For example, Mountain Time is for one hour in the spring two hours ahead of Pacific Time instead of the usual one hour ahead, and instead of one hour in the autumn, briefly zero hours ahead of Pacific Time.

The dates on which clocks change vary with location and year; consequently, the time differences between regions also vary throughout the year. For example, Paris (which uses Central European Time) is usually six hours ahead of New York City (which uses North American Eastern Time), except for a few weeks in March and October/November when it is five hours ahead. Paris and Santiago are six hours apart during the northern summer, four hours during the southern summer, and five hours for a few weeks per year. Since 1996, European Summer Time has been observed from the last Sunday in March to the last Sunday in October; previously the rules were not uniform across the European Union.[58] Starting in 2007, most of the United States and Canada observed DST from the second Sunday in March to the first Sunday in November, almost two-thirds of the year.[59] Moreover, the beginning and ending dates are roughly reversed between the northern and southern hemispheres because spring and autumn are displaced six months. For example, mainland Chile observes DST from the second Saturday in October to the second Saturday in March, with transitions at the local clock's 24:00.[60] In some countries, clocks are governed by regional jurisdictions within the country such that some jurisdictions change and others do not; this is currently the case in Australia, Canada, and the United States.[61][62]

From year to year, the dates on which to change clock may also move for political or social reasons. The Uniform Time Act of 1966 formalized the United States' period of daylight saving time observation as lasting six months (it was previously declared locally); this period was extended to seven months in 1986, and then to eight months in 2005.[63][64][65] The 2005 extension was motivated in part by lobbyists from the candy industry, seeking to increase profits by including Halloween (31 October) within the daylight saving time period.[66] In recent history, Australian state jurisdictions not only changed at different local times but sometimes on different dates. For example, in 2008 most states there that observed daylight saving time changed clocks forward on 5 October, but Western Australia changed on 26 October.[67]

## Politics, religion and sport

[edit]

The concept of daylight saving has caused controversy since its early proposals.[68] Winston Churchill argued that it enlarges "the opportunities for the pursuit of health and happiness among the millions of people who live in this country"[69] and pundits have dubbed it "Daylight Slaving Time".[70] Retailing, sports, and tourism interests have historically favored daylight saving, while agricultural and evening-entertainment interests (and some religious groups[71][72][73][74]) have opposed it; energy crises and war prompted its initial adoption.[75]

Willett's 1907 proposal illustrates several political issues. It attracted many supporters, including Arthur Balfour, Churchill, David Lloyd George, Ramsay MacDonald, King Edward VII (who used half-hour DST or "Sandringham time" at Sandringham), the managing director of Harrods, and the manager of the National Bank Ltd.[76] However, the opposition proved stronger, including Prime Minister H. H. Asquith, William Christie (the Astronomer Royal), George Darwin, Napier Shaw (director of the Meteorological Office), many agricultural organizations, and theatre-owners. After many hearings, a parliamentary committee vote narrowly rejected the proposal in 1909. Willett's allies introduced similar bills every year from 1911 through 1914, to no avail.[77] People in the US demonstrated even more skepticism; Andrew Peters introduced a DST bill to the House of Representatives in May 1909, but it soon died in committee.[78]

Retailers generally favor DST; United Cigar Stores hailed a 1918 DST bill.

Germany and its allies led the way in introducing DST during World War I on 30 April 1916, aiming to alleviate hardships due to wartime coal shortages and air-raid blackouts. The political equation changed in other countries; the United Kingdom used DST first on 21 May 1916.[79] US retailing and manufacturing interests—led by Pittsburgh industrialist Robert Garland—soon began lobbying for DST, but railroads opposed the idea. The US' 1917 entry into the war overcame objections, and DST started in 1918.[80]

The end of World War I brought a change in DST use. Farmers continued to dislike DST, and many countries repealed it—like Germany itself, which dropped DST from 1919 to 1939 and from 1950 to 1979.[81] Britain proved an exception; it retained DST nationwide but adjusted transition dates over the years for several reasons, including special rules during the 1920s and 1930s to avoid clock shifts on Easter mornings. As of 2009[update], summer time began annually on the last Sunday in March under a European Community directive, which may be Easter Sunday (as in 2016).[58] In the US, Congress repealed DST after 1919. President Woodrow Wilson—an avid golfer like Willett—vetoed the repeal twice, but his second veto was overridden.[82] Only a few US cities retained DST locally,[83] including New York (so that its financial exchanges could maintain an hour of arbitrage trading with London), and Chicago and Cleveland (to keep pace with New York).[84] Wilson's successor as president, Warren G. Harding, opposed DST as a "deception", reasoning that people should instead get up and go to work earlier in the summer. He ordered District of Columbia federal employees to start work at 8 am rather than 9 am during the summer of 1922. Some businesses followed suit, though many others did not; the experiment was not repeated.[15]

Since Germany's adoption of DST in 1916, the world has seen many enactments, adjustments, and repeals of DST, with similar politics involved.[85] The history of time in the United States features DST during both world wars, but no standardization of peacetime DST until 1966.[86][87] St. Paul and Minneapolis, Minnesota, kept different clocks for two weeks in May 1965: the capital city decided to switch to daylight saving time, while Minneapolis opted to follow the later date set by state law.[88][89] In the mid-1980s, Clorox and 7-Eleven provided the primary funding for the Daylight Saving Time Coalition behind the 1987 extension to US DST. Both senators from Idaho, Larry Craig and Mike Crapo, voted for it based on the premise that fast-food restaurants sell more French fries (made from Idaho potatoes) during DST.[90]

A referendum on the introduction of daylight saving took place in Queensland, Australia, in 1992, after a three-year trial of daylight saving. It was defeated with a 54.5% "no" vote, with regional and rural areas strongly opposed, and those in the metropolitan southeast in favor.[91]

In 2003, the United Kingdom's Royal Society for the Prevention of Accidents supported a proposal to observe year-round daylight saving time, but it has been opposed by some industries, by some postal workers and farmers, and particularly by those living in the northern regions of the UK.[13]

In 2005, the Sporting Goods Manufacturers Association and the National Association of Convenience Stores successfully lobbied for the 2007 extension to US DST.[92]

In December 2008, the Daylight Saving for South East Queensland (DS4SEQ) political party was officially registered in Queensland, advocating the implementation of a dual-time-zone arrangement for daylight saving in South East Queensland, while the rest of the state maintained standard time.[93] DS4SEQ contested the March 2009 Queensland state election with 32 candidates and received one percent of the statewide primary vote, equating to around 2.5% across the 32 electorates contested.[94] After a three-year trial, more than 55% of Western Australians voted against DST in 2009, with rural areas strongly opposed.[95] Queensland Independent member Peter Wellington introduced the Daylight Saving for South East Queensland Referendum Bill 2010 into the Queensland parliament on 14 April 2010, after being approached by the DS4SEQ political party, calling for a referendum at the next state election on the introduction of daylight saving into South East Queensland under a dual-time-zone arrangement.[96] The Queensland parliament rejected Wellington's bill on 15 June 2011.[97]

Russia declared in 2011 that it would stay in DST all year long (UTC+4:00) and Belarus followed with a similar declaration.[98] (The Soviet Union had operated under permanent "summer time" from 1930 to at least 1982.) Russia's plan generated widespread complaints due to the dark of winter-time mornings, and thus was abandoned in 2014.[99] The country changed its clocks to standard time (UTC+3:00) on 26 October 2014, intending to stay there permanently.[100]

In the United States, Arizona (with the exception of the Navajo Nation), Hawaii, and the five populated territories (American Samoa, Guam, Puerto Rico, the Northern Mariana Islands, and the US Virgin Islands) do not participate in daylight saving time.[101][102] Indiana only began participating in daylight saving time as recently as 2006. Between 2018 and 2024, former Florida Republican Senator Marco Rubio repeatedly filed bills to extend daylight saving time permanently into winter, without success.[103]

Mexico observed summertime daylight saving time starting in 1996. In late 2022, the nation's clocks "fell back" for the last time, in restoration of permanent standard time.[104]

### Religion

[edit]

Some religious groups and individuals have opposed DST on religious grounds. For religious Muslims and Jews it makes religious practices such as prayer and fasting more difficult or inconvenient.[105][72][73][74] Some Muslim countries, such as Morocco, have temporarily abandoned DST during Ramadan.[74]

In Israel, DST has been a point of contention between the religious and secular, resulting in fluctuations over the years, and a shorter DST period than in the EU and US. Religious Jews prefer a shorter DST[a] due to DST delaying scheduled morning prayers, thus conflicting with standard working and business hours. Additionally, DST is ended before Yom Kippur (a 25-hour fast day starting and ending at sunset, much of which is spent praying in synagogue until the fast ends at sunset) since DST would result in the day ending later, which many feel makes it more difficult.[b][72][106]

In the US, Orthodox Jewish groups have opposed extensions to DST,[107] as well as a 2022 bipartisan bill that would make DST permanent, saying it will "interfere with the ability of members of our community to engage in congregational prayers and get to their places of work on time."[73]

## Effects

[edit]

Main article: Analysis of daylight saving time

### Effects on electricity consumption

[edit]

William Willett independently proposed DST in 1907 and advocated it tirelessly.[108]

Proponents of DST generally argue that it saves energy, promotes outdoor leisure activity in the evening (in summer), and is therefore good for physical and psychological health,[109] reduces traffic accidents, reduces crime or is good for business.[110] Opponents argue the actual energy savings are inconclusive.[111]

Although energy conservation goals still remain under certain conditions,[112] energy usage patterns have greatly changed since then. In a publication from 2025, based on this change in consumption patterns, such as air conditioning systems, additional consumption is expected to occur more frequently during daylight saving time in the future.[113] Electricity use is greatly affected by geography, climate, and economics, so the results of a study conducted in one place may not be relevant to another country or climate.[114] Nevertheless, while overall electricity usage does not decrease, the evening peak demand is flattened, which in turn has a direct impact on generation costs.[113]

A 2017 meta-analysis of 44 studies found that DST leads to electricity savings of 0.3% during the days when DST applies.[115][116] Several studies have suggested that DST increases motor fuel consumption,[114] but a 2008 United States Department of Energy report found no significant increase in motor gasoline consumption due to the 2007 United States extension of DST.[117] An early goal of DST was to reduce evening usage of incandescent lighting, once a primary use of electricity.[118]

### Economic effects

[edit]

It has been argued that clock shifts correlate with decreased economic efficiency and that in 2000, the daylight-saving effect implied an estimated one-day loss of $31 billion on US stock exchanges.[119] Others have asserted that the observed results depend on methodology[120] and disputed the findings,[121] though the original authors have refuted points raised by disputers.[122]

### Effects on health

[edit]

There are measurable adverse effects of clock-shifts on human health.[123] It has been shown to disrupt human circadian rhythms,[124] negatively affecting human health in the process,[125] and that the yearly DST clock-shifts can increase health risks such as heart attacks[126] and traffic accidents.[127][128]

A 2017 study in the American Economic Journal: Applied Economics estimated that "the transition into DST caused over 30 deaths at a social cost of $275 million annually", primarily by increasing sleep deprivation.[129]

A correlation between clock shifts and increase in traffic accidents has been observed in North America and the UK but not in Finland or Sweden.[130] Four reports have found that this effect is smaller than the overall reduction in traffic fatalities.[131][132][133][134] According to data shared by Titan Casket, hospitals see a 24% increase in heart attacks[135] and a 6% increase in fatal crashes[136] each year when the time changes. In 2018, the European Parliament, reviewing a possible abolition of DST, approved a more in-depth evaluation examining the disruption of the human body's circadian rhythms which provided evidence suggesting the existence of an association between DST clock-shifts and a modest increase of occurrence of acute myocardial infarction, especially in the first week after the spring shift.[137] However a Netherlands study found, against the majority of investigations, contrary or minimal effect.[138] Year-round standard time (not year-round DST) is proposed by some to be the preferred option for public health and safety.[139][140][141][142][143] Clock shifts were found to increase the risk of heart attack by 10 percent,[126] and to disrupt sleep and reduce its efficiency.[144] Effects on seasonal adaptation of the circadian rhythm can be severe and last for weeks.[145]

### Effects on social relations

[edit]

DST hurts prime-time television broadcast ratings,[146][126] drive-ins and other theaters.[147] Artificial outdoor lighting has a marginal and sometimes even contradictory influence on crime and fear of crime.[148]

Later sunsets from DST are thought to affect behavior; for example, increasing participation in after-school sports programs or outdoor afternoon sports such as golf, and attendance at professional sporting events.[149] Advocates of daylight saving time argue that having more hours of daylight between the end of a typical workday and evening induces people to consume other goods and services.[150][110][151]

In 2022, a publication of three replicating studies of individuals, between individuals, and transecting societies, demonstrated that sleep loss affects the human motivation to help others, which in its fMRI findings is "associated with deactivation of key nodes within the social cognition brain network that facilitates prosociality." Furthermore, they detected, through analysis of over three million real-world charitable donations, that the loss of sleep inflicted by the transition to daylight saving time reduces altruistic giving compared to controls (being states not implementing DST). They conclude that the effects on civil society are "non-trivial".[152]

Another study, which also examined sleep manipulation due to the shift to daylight saving time in the spring, analyzed archival data from judicial punishment imposed by US federal courts which showed sleep-deprived judges exact more severe penalties.[153]

### Inconvenience

[edit]

DST's clock shifts have the disadvantage of complexity. People must remember to change their clocks; this can be time-consuming, particularly for mechanical clocks that cannot be moved backward safely.[154] People who work across time zone boundaries need to keep track of multiple DST rules, as not all locations observe DST or observe it the same way. The length of the calendar day becomes variable; it is no longer always 24 hours. Disruption to meetings, travel, broadcasts, billing systems, and records management is common, and can be expensive.[155] During an autumn transition from 02:00 to 01:00, a clock shows local times from 01:00:00 through 01:59:59 twice, possibly leading to confusion.[156]

Many farmers oppose DST, particularly dairy farmers as the milking patterns of their cows do not change with the time,[126][157][158] and others whose hours are set by the sun.[159] There is concern for schoolchildren who are out in the darkness during the morning due to late sunrises.[126]

### Remediation

[edit]

Some clock-shift problems could be avoided by adjusting clocks continuously[160] or at least more gradually[161]—for example, Willett at first suggested weekly 20-minute transitions—but this would add complexity and has never been implemented. DST inherits and can magnify the disadvantages of standard time. For example, when reading a sundial, one must compensate for it along with time zone and natural discrepancies.[162] Also, sun-exposure guidelines such as avoiding the sun within two hours of noon become less accurate when DST is in effect.[163]

## Terminology

[edit]

As explained by Richard Meade in the English Journal of the (American) National Council of Teachers of English, the form daylight savings time (with an "s") was already much more common than the older form daylight saving time in American English ("the change has been virtually accomplished") in 1978. Nevertheless, dictionaries such as Merriam-Webster's, American Heritage, and Oxford, which typically describe actual usage instead of prescribing outdated usage (and therefore also list the newer form), still list the older form first. This is because the older form is still very common in print and is preferred by many editors. ("Although daylight saving time is considered correct, daylight savings time (with an "s") is commonly used.")[164] The first two words are sometimes hyphenated (daylight-saving(s) time). Merriam-Webster's also lists the forms daylight saving, daylight savings (both without "time"), and daylight time.[165] The Oxford Dictionary of American Usage and Style explains the development and current situation as follows:

> Although the singular form daylight saving time is the original one, dating from the early 20th century—and is preferred by some usage critics—the plural form is now extremely common in AmE. [...] The rise of daylight savings time appears to have resulted from the avoidance of a miscue: when saving is used, readers might puzzle momentarily over whether saving is a gerund (the saving of daylight) or a participle (the time for saving). [...] Using savings as the adjective—as in savings account or savings bond—makes perfect sense. More than that, it ought to be accepted as the better form.[166]

In Britain, Willett's 1907 proposal[36] used the term daylight saving, but by 1911, the term summer time replaced daylight saving time in draft legislation.[108] The same or similar expressions are used in many other languages: Sommerzeit in German, zomertijd in Dutch, kesäaika in Finnish, horario de verano or hora de verano in Spanish, and heure d'été in French.[79]

The name of local time typically changes when DST is observed. American English replaces standard with daylight: for example, Pacific Standard Time (PST) becomes Pacific Daylight Time (PDT). In the United Kingdom, the standard term for UK time when advanced by one hour is British Summer Time (BST), and British English typically inserts summer into other time zone names, e.g. Central European Time (CET) becomes Central European Summer Time (CEST).

In North American English, people use the mnemonic "spring forward, fall back" (also "spring ahead ...", "spring up ...", and "... fall behind") to remember the direction in which to shift the clocks.[167][68]

## Computing

[edit]

A 2001 US public service advertisement reminded people to adjust clocks.

Changes to DST rules cause problems in existing computer installations. For example, the 2007 change to DST rules in North America required that many computer systems be upgraded, with the greatest onus on e-mail and calendar programs. The upgrades required a significant effort by corporate information technologists.[168]

Some applications standardize on UTC to avoid problems with clock shifts and time zone differences.[169] Likewise, most modern operating systems internally handle and store all times as UTC and only convert to local time for display.[170][171] However, even if UTC is used internally, the systems still require external leap second updates and time zone information to correctly calculate local time as needed. Many systems in use today base their date/time calculations from data derived from the tz database also known as zoneinfo.

### IANA time zone database

[edit]

The Internet Assigned Numbers Authority (IANA) tz database maps a name to the named location's historical and predicted clock shifts. This database is used by many computer software systems, including most Unix-like operating systems, Java, and the Oracle RDBMS;[172] HP's "tztab" database is similar but incompatible.[173] When temporal authorities change DST rules, zoneinfo updates are installed as part of ordinary system maintenance. In Unix-like systems the TZ environment variable specifies the location name, as in `TZ=':America/New_York'`. In many of those systems there is also a system-wide setting that is applied if the TZ environment variable is not set: this setting is controlled by the contents of the `/etc/localtime` file, which is usually a symbolic link or hard link to one of the zoneinfo files. Internal time is stored in time-zone-independent Unix time; the TZ is used by each of potentially many simultaneous users and processes to independently localize time display.

Older or stripped-down systems may support only the TZ values required by POSIX, which specify at most one start and end rule explicitly in the value. For example, `TZ='EST5EDT,M3.2.0/02:00,M11.1.0/02:00'` specifies time for the eastern United States starting in 2007. Such a TZ value must be changed whenever DST rules change, and the new value applies to all years, mishandling some older timestamps.[174]

## Opposition to clock changes

[edit]

See also: Permanent time observation in the United States, Decree time in Russia, Summer time in Europe § Future, Daylight saving time in Asia § Asian countries not using DST, and Daylight saving time in Brazil

Opposition to changing the clocks twice a year broadly takes three forms:

* a preference for year-round daylight saving time,
* a preference for year-round standard time, and
* a desire to "lock the clock", regardless of whether the result is year-round daylight or year-round standard time.[175][176]

The William Willett Memorial Sundial in Petts Wood, south London, is always on DST.

A move to permanent daylight saving time (staying on summer hours all year with no clock shifts) is sometimes advocated and is currently implemented in some jurisdictions such as Argentina, Belarus,[177] Iceland, Kyrgyzstan, Morocco,[55] Namibia, Northern Cyprus, Paraguay, Saskatchewan, Singapore, Syria, Turkey, Turkmenistan, Uzbekistan, and Yukon. Although Saskatchewan follows Central Standard Time, its capital city Regina experiences solar noon close to 13:00, in effect putting the city on permanent daylight time. Similarly, Yukon is classified as being in the Mountain Time Zone, though in effect it observes permanent Pacific Daylight Time to align with the Pacific time zone in summer, but local solar noon in the capital Whitehorse occurs nearer to 14:00, in effect putting Whitehorse on "double daylight time".[citation needed]

The United Kingdom and Ireland put clocks forward by an extra hour during World War II and experimented with year-round summer time between 1968 and 1971.[178] Russia switched to permanent DST from 2011 to 2014, but the move proved unpopular because of the extremely late winter sunrises; in 2014, Russia switched permanently back to standard time.[179] However, the change to permanent DST has proven popular in Turkey, with the Minister of Energy and Natural Resources saying the practice saves "millions in energy costs and reduces depression and anxiety levels associated with short exposure to daylight".[180]

In September 2018, the European Commission proposed to end seasonal clock changes as of 2019.[181] Member states would have the option of observing either daylight saving time all year round or standard time all year round. In March 2019, the European Parliament approved the commission's proposal, while deferring implementation from 2019 until 2021.[182] In response to this proposition, the European Sleep Research Society stated "installing permanent Central European Time (CET, standard time or 'wintertime') is the best option for public health."[183] As of October 2020[update], the decision has not been confirmed[Needs update] by the Council of the European Union.[184] The council has asked the commission to produce a detailed assessment of its effects, but the Commission considers that the onus is on the Member States to find a common position in Council.[185] As a result, progress on the issue is effectively blocked.[186]

In the United States, several states have enacted legislation to implement permanent DST, but the bills would require Congress to change federal law in order to take effect. The Uniform Time Act of 1966 permits states to opt out of DST and observe permanent standard time, but it does not permit permanent DST.[101][187] Florida senator Marco Rubio in particular has promoted changing the federal law to implement permanent DST,[188] with the support of the Florida Chamber of Commerce seeking to boost evening revenue.[189] In 2022, Rubio's "Sunshine Protection Act" passed the United States Senate without committee review by way of voice consent, with many senators afterward stating they were unaware of the vote or its topic.[190] The bill was stopped in the US House, where questions were raised as to whether permanent DST or standard time would be more beneficial.[103][191] Polling as of 2025 shows a majority of Americans polled now prefer to permanently end DST, with 54% of Americans reporting that a permanent switch to standard time would be preferrable. The emergent majority indicates that permanent DST would also be preferred over no change, with the least popular activity being the changing of the time twice per year regardless of DST or standard time being the permanent method of keeping time.[1][192]

Advocates cite the same advantages as normal DST without the problems associated with the twice-yearly clock shifts. Additional benefits have also been cited, including safer roadways, boosting the tourism industry, and energy savings. Detractors cite the relatively late sunrises, particularly in winter, that year-round DST entails.[193]

Some experts in circadian rhythms and sleep health recommend year-round standard time as the preferred option for public health and safety.[139][140][141][142] However, some experts state that permanent daylight saving time is still a better option when compared to annual clock changes.[194][195] Several chronobiology societies have published position papers against adopting DST permanently. A paper by the Society for Research on Biological Rhythms states: "based on comparisons of large populations living in DST or ST or on western versus eastern edges of time zones, the advantages of permanent ST outweigh switching to DST annually or permanently."[196] The World Federation of Societies for Chronobiology recommended "reassigning countries and regions to their actual sun-clock based time zones" and held the position of being "against the switching between DST and Standard Time and even more so against adopting DST permanently."[197] The American Academy of Sleep Medicine (AASM) holds the position that "seasonal time changes should be abolished in favor of a fixed, national, year-round standard time,"[198] and that "standard time is a better option than daylight saving time for our health, mood and well-being."[199] Their position was endorsed by 20 other organizations, including the American College of Chest Physicians, National Safety Council, and National PTA.[200]

Surveys reported between 2021 and 2022 by the National Sleep Foundation, YouGov, CBS, and Monmouth University indicate more Americans would prefer permanent DST.[201][202][203] A 2019 survey by the National Opinion Research Center and a 2021 survey by the Associated Press indicate more Americans would prefer permanent Standard Time.[204][205] The National Sleep Foundation, YouGov, and Monmouth University polls leaned significantly in favor of seeing daylight saving time made permanent. The Monmouth University poll reported 44% preferring year-round DST and 13% preferring year-round standard time.[202] The NORC at the University of Chicago found 79% of those interviewed to be in favor of permanent DST during the Oil Crisis in December 1973; 42% of poll takers supported it the following February.[206]

## See also

[edit]

* Daylight saving time by country
* Daylight saving time in Africa
* Daylight saving time in Asia
* Summer time in Europe
* Daylight saving time in the Americas
* Daylight saving time in the United States
* Daylight saving time in Canada
* Daylight saving time in Oceania
* Analysis of daylight saving time
* Winter time (clock lag)

## Notes

[edit]

1. ^ Starting after Passover and ended before Yom Kippur (less than 180 days)
2. ^ Although DST does not affect the duration of the fast, which is 25 hours regardless, many find it easier to start and end earlier rather than later.

## References

[edit]

1. ^ a b Evans, Mary Claire; Jones, Jeffrey M. (4 March 2025). "More Than Half in U.S. Want Daylight Saving Time Sunsetted". Gallup, Inc. Retrieved 11 March 2025.
2. ^ "Places around the world that opt out of daylight savings - and why". www.bbc.com. 6 March 2025. Retrieved 11 March 2025.
3. ^ "7 Things to Know About Daylight Saving Time | Johns Hopkins | Bloomberg School of Public Health". publichealth.jhu.edu. 9 March 2023. Retrieved 11 March 2025.
4. ^ Haines, Julia (6 November 2023). "Which Countries Observe Daylight Saving Time?". US News & World Report. Retrieved 4 November 2024.
5. ^ "No DST in Most of Arizona".
6. ^ "Did Ben Franklin Invent Daylight Saving Time?". The Franklin Institute. 7 July 2017. Archived from the original on 1 June 2021. Retrieved 5 August 2021.
7. ^ "Full text – Benjamin Franklin – The Journal of Paris, 1784". www.webexhibits.org. Archived from the original on 15 November 2017. Retrieved 5 August 2021.
8. ^ a b Gibbs, George. "Hudson, George Vernon". Dictionary of New Zealand Biography. Ministry for Culture and Heritage. Retrieved 22 March 2015.
9. ^ a b Ogle, Vanessa (2015). The Global Transformation of Time: 1870–1950. Harvard University Press. p. 51\. ISBN 978-0-674-28614-6. Archived from the original on 22 March 2021. Retrieved 4 December 2020.
10. ^ a b "Time to change your clocks – but why?". Northern Ontario Travel. 8 March 2018. Archived from the original on 10 October 2018. Retrieved 9 October 2018.
11. ^ a b Daylight Saving Time, archived from the original on 9 October 2018, retrieved 8 October 2018
12. ^ "Daylight savings time". Session Weekly. Minnesota House Public Information Office. 1991. Archived from the original on 16 June 2016. Retrieved 7 August 2013.
13. ^ a b "Single/Double Summer Time policy paper" (PDF). Royal Society for the Prevention of Accidents. October 2006. Archived from the original (PDF) on 13 September 2012.
14. ^ a b G. V. Hudson (1895). "On seasonal time-adjustment in countries south of lat. 30°". Transactions and Proceedings of the New Zealand Institute. 28: 734. Archived from the original on 30 March 2019. Retrieved 3 April 2009.
15. ^ a b Seize the Daylight (2005), pp. 115–118.
16. ^ Mikkelson, David (13 March 2016). "Daylight Saving Time". Snopes. Retrieved 17 October 2016.
17. ^ a b "100 years of British Summer Time". National Maritime Museum. 2008. Archived from the original on 28 December 2014.
18. ^ Yuhas, Alan (6 March 2024). "When Is Daylight Saving Time?". The New York Times. Retrieved 20 March 2024. "One of the oldest arguments for daylight saving time is that it can save energy costs. There have been many conflicting studies about whether actually it does."
19. ^ Visé, Daniel de (3 November 2023). "Is Daylight saving time a scam? Time, money may not be saved". USA TODAY. Retrieved 20 March 2024. " ... researchers announced that the nation had reduced its energy consumption by an annual rate of 0.03%. The meager savings came in reduced electricity consumption in the evenings during the extra days of daylight time. Other research, however, has suggested the reverse: The semiannual time shift exacts a cost, and daylight time nets little or no savings."
20. ^ Eggimann Sven, Robin Mutschler, Kristina Orehounig, Massimo Fiorentini (2023), "Climate change shifts the trade-off between lower cooling and higher heating demand from daylight saving time in office buildings", Environmental Research Letters, vol. 18, no. 2, p. 024001, Bibcode:2023ERL....18b4001E, doi:10.1088/1748-9326/acb0e3, ISSN 1748-9326`{{citation}}`: CS1 maint: multiple names: authors list (link)
21. ^ Swanson, Anna (11 March 2016). "Why daylight saving time isn't as terrible as people think". The Washington Post. Archived from the original on 11 March 2018. Retrieved 27 March 2018.
22. ^ Berthold (1918). "Daylight saving in ancient Rome". The Classical Journal. 13 (6): 450–451.
23. ^ Jérôme Carcopino (1968). "The days and hours of the Roman calendar". Daily Life in Ancient Rome: The People and the City at the Height of the Empire. Yale University Press. ISBN 978-0-300-00031-3.
24. ^ Robert Kaplan (2003). "The holy mountain". The Atlantic. 292 (5): 138–141.
25. ^ Hertzel Hillel Yitzhak (2006). "When to recite the blessing". Tzel HeHarim: Tzitzit. Nanuet, NY: Feldheim. pp. 53–58\. ISBN 978-1-58330-292-7.
26. ^ Manser, Martin H. (2007). The Facts on File dictionary of proverbs. Infobase Publishing. p. 70\. ISBN 978-0816066735. Archived from the original on 4 September 2015. Retrieved 26 October 2011.
27. ^ Benjamin Franklin; William Temple Franklin; William Duane (1834). Memoirs of Benjamin Franklin. McCarty & Davis. p. 477\. Archived from the original on 1 February 2017. Retrieved 20 October 2016.
28. ^ Seymour Stanton Block (2006). "Benjamin Franklin: America's inventor". American History. Archived from the original on 29 March 2019. Retrieved 9 March 2009.
29. ^ Benjamin Franklin, writing anonymously (26 April 1784). "Aux auteurs du Journal". Journal de Paris (in French) (117): 511–513. Its first publication was in the journal's "Économie" section in a French translation. The revised English version Archived 15 November 2017 at the Wayback Machine [cited 13 February 2009] is commonly called "An Economical Project", a title that is not Franklin's; see A.O. Aldridge (1956). "Franklin's essay on daylight saving". American Literature. 28 (1): 23–29\. doi:10.2307/2922719. ISSN 0002-9831. JSTOR 2922719.
30. ^ Eviatar Zerubavel (1982). "The standardization of time: a sociohistorical perspective". The American Journal of Sociology. 88 (1): 1–23\. doi:10.1086/227631. S2CID 144994119.
31. ^ Luxan, Manuel (1810). Reglamento para el gobierno interior de las Cortes (PDF). Congreso de los Diputados. Cadiz. Archived (PDF) from the original on 5 September 2018.
32. ^ Martín Olalla, José María (3 September 2018). "La gestión de la estacionalidad". El Mundo (in Spanish). Unidad Editorial. Archived from the original on 4 September 2018. Retrieved 4 September 2018.
33. ^ G. V. Hudson (1898). "On seasonal time". Transactions and Proceedings of the New Zealand Institute. 31: 577–588\. Archived from the original on 23 May 2010. Retrieved 3 April 2009.
34. ^ Lee, L. P. (1 October 1947). "New Zealand time". New Zealand Geographer. 3 (2): 198. Bibcode:1947NZGeo...3..197L. doi:10.1111/j.1745-7939.1947.tb01466.x.
35. ^ Seize the Daylight (2005), p. 3.
36. ^ a b William Willett (1907). The waste of daylight (1st ed.). Archived from the original on 30 March 2019. Retrieved 9 March 2009 - via Daylight Saving Time.
37. ^ "Daylight Saving Bill". Parliamentary Debates (Hansard). House of Commons. 12 February 1908. col. 155–156.
38. ^ Moro, Teviah (16 July 2009). "Faded Memories for Sale". Orillia Packet and Times. Orillia, Ontario. Archived from the original on 26 August 2016. Retrieved 20 October 2016.
39. ^ League of Nations (20 October 1923). Regulation of summer time (PDF). Geneva. pp. 5, 22–24\. Archived (PDF) from the original on 24 October 2020. Retrieved 4 September 2020.`{{cite book}}`: CS1 maint: location missing publisher (link)
40. ^ Seize the Daylight (2005), pp. 51–89.
41. ^ a b c Feltman, Rachel (6 March 2015). "Perspective | Five myths about daylight saving time". Washington Post. ISSN 0190-8286. Retrieved 16 March 2022.
42. ^ a b Victor, Daniel (11 March 2016). "Daylight Saving Time: Why Does It Exist? (It's Not for Farming)". The New York Times. ISSN 0362-4331. Retrieved 16 March 2022.
43. ^ a b c Klein, Christopher. "8 Things You May Not Know About Daylight Saving Time". .History.com. Retrieved 16 March 2022.
44. ^ a b "When Daylight Saving Time Was Year-Round". Time. Retrieved 16 March 2022.
45. ^ a b c A Time-Change Timeline, National Public Radio, 8 March 2007
46. ^ Graphics, WSJ com News. "World War I Centenary: Daylight-Saving Time". The Wall Street Journal. Retrieved 16 March 2022.
47. ^ "Information for visitors". Lord Howe Island Tourism Association. Archived from the original on 3 May 2009. Retrieved 20 April 2009.
48. ^ "Time Zone & Clock Changes in Troll Station, Antarctica". timeanddate.com. Retrieved 18 October 2023.
49. ^ "Time Zone Abbreviations – Worldwide List", timeanddate.com, archived from the original on 21 August 2018, retrieved 14 May 2020
50. ^ MacRobert, Alan (18 July 2006). "Time in the Sky and the Amateur Astronomer". Sky and Telescope. Archived from the original on 11 July 2020. Retrieved 14 May 2020.
51. ^ "Standard Time (Amendment) Act, 1971, Section 1". electronic Irish Statute Book. Archived from the original on 30 October 2013. Retrieved 3 June 2019.
52. ^ "Time Zones in Ireland". timeanddate.com. Archived from the original on 31 December 2019. Retrieved 14 May 2020.
53. ^ "Time Zones in the United Kingdom". timeanddate.com. Archived from the original on 8 July 2020. Retrieved 14 May 2020.
54. ^ Kasraoui, Safaa (16 April 2019). "Morocco to Switch Clocks Back 1 Hour on May 5 for Ramadan". Morocco World News. Archived from the original on 5 June 2019. Retrieved 5 June 2019.
55. ^ a b "Release of the Moroccan Official Journal" (PDF) (Press release) (in Arabic). Archived from the original (PDF) on 26 October 2019. Retrieved 31 October 2018.
56. ^ "Time Zones in Morocco". timeanddate.com. Archived from the original on 27 June 2020. Retrieved 15 May 2020.
57. ^ National Physical Laboratory (31 March 2016). "At what time should clocks go forward or back for summer time (FAQ – Time)". Archived from the original on 11 October 2016. Retrieved 17 October 2016. "The time at which summer time begins and ends is given in the relevant EU Directive and UK Statutory Instrument as 1 am. Greenwich Mean Time (GMT)... All time signals are based on Coordinated Universal Time (UTC), which can be almost one second ahead of, or behind, GMT so there is a brief period in the UK when the directive is not being strictly followed."
58. ^ a b c Joseph Myers (17 July 2009). "History of legal time in Britain".
59. ^ Tom Baldwin (12 March 2007). "US gets summertime blues as the clocks go forward 3 weeks early". The Times. London. Archived from the original on 2 April 2019. Retrieved 2 November 2018.
60. ^ "Historia Hora Oficial de Chile" (in Spanish). Chilean Hydrographic and Oceanographic Service. 1 October 2008. Archived from the original on 2 April 2019. Retrieved 15 November 2014.
61. ^ Seize the Daylight (2005), pp. 179–180.
62. ^ "Why Arizona doesn't observe daylight-saving time". USA Today. Archived from the original on 30 March 2019. Retrieved 26 August 2017.
63. ^ Downing, Michael (2018). "One Hundred Years Later, the Madness of Daylight Saving Time Endures". The Conversation. Archived from the original on 19 February 2020. Retrieved 14 May 2020.
64. ^ Korch, Travers (2015). "The Financial History of Daylight Saving". Bankrate. Archived from the original on 11 July 2020. Retrieved 14 May 2020.
65. ^ "Energy Policy Act of 2005, Public Law 109-58 § 110". 8 August 2005. Archived from the original on 16 July 2009. Retrieved 11 July 2007.
66. ^ Morgan, Thad (2017). "The Sweet Relationship Between Daylight Saving Time and Halloween". History. Archived from the original on 12 May 2020. Retrieved 14 May 2020.
67. ^ "Implementation dates of daylight saving time within Australia". Bureau of Meteorology. 22 September 2009. Archived from the original on 4 April 2016. Retrieved 11 July 2007.
68. ^ a b DST practices and controversies:
* Spring Forward (2005)
* Seize the Daylight (2005)
69. ^ Winston S. Churchill (28 April 1934). "A silent toast to William Willett". Pictorial Weekly.
70. ^ Seize the Daylight (2005), p. 117.
71. ^ Seize the Daylight (2005), pp. "God's time" 106, 135, 154, 175, "religious" 208, "Jews" 212, "Israel" 221-222.
72. ^ a b c
* Stoil, Rebecca Anna (2010). "Politicians fight over setting the clock back". The Jerusalem Post.
* Cohen, Benyamin (2022). "Senate passes bill to make daylight saving time permanent, complicating life for observant Jews". The Forward.
73. ^ a b c
* Kornbluh, Jacob. "Orthodox groups launch uphill battle against daylight saving time bill". The Forward.
* Berman, Jesse (18 March 2022). "What permanent daylight saving time could mean for the Jewish community". Baltimore Jewish Times.
74. ^ a b c Fitzpatrick, Kyle (21 October 2019). "When do the clocks change around the world? And why?". The Guardian. ISSN 0261-3077. Archived from the original on 1 November 2020. Retrieved 4 December 2020. "Most Islamic countries do not use daylight saving time as during Ramadan it can mean that the evening dinner is delayed till later in the day."
75. ^ Seize the Daylight (2005), p. xi.
76. ^ Slattery, Sir Matthew (1972). The National Bank, 1835–1970 (Privately published ed.). The National Bank.
77. ^ Seize the Daylight (2005), pp. 12–24.
78. ^ Seize the Daylight (2005), pp. 72–73.
79. ^ a b Seize the Daylight (2005), pp. 51–70.
80. ^ Seize the Daylight (2005), pp. 80–101.
81. ^ "Time Changes in Berlin Over the Years". timeanddate.com. Archived from the original on 27 May 2019. Retrieved 27 May 2019.
82. ^ Seize the Daylight (2005), pp. 103–110.
83. ^ Robert Garland (1927). Ten years of daylight saving from the Pittsburgh standpoint. Carnegie Library of Pittsburgh. OCLC 30022847. Archived from the original on 28 September 2006.
84. ^ Spring Forward (2005), pp. 47–48.
85. ^ David P. Baron (2005). "The politics of the extension of daylight saving time". Business and its Environment (5th ed.). Prentice Hall. ISBN 978-0-13-187355-1.
86. ^ Seize the Daylight (2005), pp. 147–155, 175–180.
87. ^ Ian R. Bartky; Elizabeth Harrison (1979). "Standard and daylight-saving time". Scientific American. 240 (5): 46–53\. Bibcode:1979SciAm.240e..46B. doi:10.1038/scientificamerican0579-46. ISSN 0036-8733.
88. ^ Murray, David. "'Chaos of time': The history of daylight saving time, why we spring forward". Great Falls Tribune. Archived from the original on 20 January 2021. Retrieved 9 November 2020.
89. ^ "Twin cities disagree over daylight savings time, 1965". St. Cloud Times. 5 May 1965. p. 1\. Archived from the original on 10 November 2020. Retrieved 9 November 2020 - via Newspapers.com.
90. ^ James C. Benfield (24 May 2001). "Statement to the U.S. House, Committee on Science, Subcommittee on Energy". Energy Conservation Potential of Extended and Double Daylight Saving Time. Serial 107-30. Archived from the original on 25 August 2007. Retrieved 11 March 2007.
91. ^ "1992 Queensland Daylight Saving Referendum" (PDF). Archived from the original (PDF) on 11 September 2017. Retrieved 25 July 2010.
92. ^ Alex Beam (26 July 2005). "Dim-witted proposal for daylight time". Boston Globe. Archived from the original on 3 March 2016. Retrieved 20 April 2020.
93. ^ "Daylight Saving group launched as new Qld political party". ABC News. 14 December 2008. Archived from the original on 4 January 2009. Retrieved 25 July 2010.
94. ^ "Total Candidates Nominated for Election by Party – 2009 State Election". Electoral Commission of Queensland (ECQ). Archived from the original on 26 February 2011. Retrieved 19 June 2010.
95. ^ Paige Taylor (18 May 2009). "Daylight saving at a sunset out west". The Australian. Archived from the original on 27 October 2011. Retrieved 5 March 2010.
96. ^ "Daylight Saving for South East Queensland Referendum Bill 2010" (PDF). 14 April 2010. Archived (PDF) from the original on 13 June 2010. Retrieved 25 July 2010.
97. ^ "Daylight saving silence 'deafening'". 16 June 2011. Archived from the original on 18 June 2011. Retrieved 19 June 2011.
98. ^ Time and Date (19 September 2011). "Eternal Daylight Saving Time (DST) in Belarus". Archived from the original on 19 October 2017. Retrieved 20 October 2016.
99. ^ "Russia abandons year-round daylight-saving time". AP. 1 July 2014. Archived from the original on 4 September 2015. Retrieved 21 October 2014.
100. ^ "Russian clocks go back for last time". BBC. 25 October 2014. Archived from the original on 26 October 2014. Retrieved 25 October 2014.
101. ^ a b "Daylight Saving Time State Legislation". National Conference of State Legislatures. Retrieved 3 January 2023.
102. ^ Buckle, Anne. "No DST in Most of Arizona". timeanddate.com. Retrieved 11 February 2022.
103. ^ a b Howell, Tom Jr. (21 December 2022). "Rubio to keep fighting for permanent daylight saving time after clock runs out for this Congress". Retrieved 3 January 2023.
104. ^ Perlmutter, Lillian (27 October 2022). "Mexico falls back but won't spring forward as summer time abolished". The Guardian. Retrieved 7 January 2023.
105. ^ Seize the Daylight (2005), pp. "Jews" 212, "Israel" 221-222.
106. ^ Seize the Daylight (2005), p. 221.
107. ^ Seize the Daylight (2005), p. 212.
108. ^ a b Seize the Daylight (2005), p. 22.
109. ^ Goodman, A, Page, A, Cooper, A (23 October 2014). "Daylight saving time as a potential public health intervention: an observational study of evening daylight and objectively-measured physical activity among 23,000 children from 9 countries". International Journal of Behavioral Nutrition and Physical Activity. 11: 84. doi:10.1186/1479-5868-11-84. PMC 4364628. PMID 25341643. S2CID 298351.
110. ^ a b "Tired of turning clocks forward and back? You have big business to thank". CBC News. Archived from the original on 4 December 2020. Retrieved 4 December 2020.
111. ^ Choi, Charles (2009), Does Daylight Saving Time Conserve Energy?, New York, NY, USA: Scientific American, archived from the original on 30 January 2014
112. ^ Dilip R. Ahuja; D. P. Sen Gupta; V. K. Agrawal (2007). "Energy savings from advancing the Indian Standard Time by half an hour" (PDF). Current Science. 93 (3): 298–302\. Archived (PDF) from the original on 1 February 2014. Retrieved 20 August 2013.
113. ^ a b Neumann, Philipp; Blanckenburg, Korbininan von (2025). "What Time Will It Be? A Comprehensive Literature Review on Daylight Saving Time". Time & Society. doi:10.1177/0961463X241310562. Retrieved 2 March 2025.
114. ^ a b Myriam B.C. Aries; Guy R. Newsham (2008). "Effect of daylight saving time on lighting energy use: a literature review". Energy Policy. 36 (6): 1858–1866\. doi:10.1016/j.enpol.2007.05.021. Archived from the original on 26 October 2019. Retrieved 25 September 2019.
115. ^ Havranek, Tomas; Herman, Dominik; Irsova, Zuzana (1 June 2018). "Does Daylight Saving Save Electricity? A Meta-Analysis". The Energy Journal. 39 (2): 35–61\. Bibcode:2018EnerJ..39...35H. doi:10.5547/01956574.39.2.thav. ISSN 1944-9089. S2CID 58919134.
116. ^ Irsova, Zuzana; Havranek, Tomas; Herman, Dominik (2 December 2017). "Daylight saving saves no energy". VoxEU.org. Archived from the original on 3 December 2017. Retrieved 2 December 2017.
117. ^ David B. Belzer; Stanton W. Hadley; Shih-Miao Chin (2008). Impact of Extended Daylight Saving Time on national energy consumption: report to Congress, Energy Policy Act of 2005, Section 110 (PDF) (Report). US Dept. of Energy. Archived from the original (PDF) on 18 May 2013.
118. ^ Roscoe G. Bartlett (24 May 2001). "Statement to the US House, Committee on Science, Subcommittee on Energy". Energy Conservation Potential of Extended and Double Daylight Saving Time. Serial 107-30. Archived from the original on 25 August 2007. Retrieved 11 March 2007.
119. ^ Mark J. Kamstra; Lisa A. Kramer; Maurice D. Levi (2000). "Losing sleep at the market: the daylight saving anomaly" (PDF). American Economic Review. 90 (4): 1005–1011\. CiteSeerX 10.1.1.714.2833. doi:10.1257/aer.90.4.1005. Archived (PDF) from the original on 21 September 2017. Retrieved 27 October 2017.
120. ^ Luisa Müller; Dirk Schiereck; Marc W. Simpson; Christian Voigt (2009). "Daylight saving effect". Journal of Multinational Financial Management. 19 (2): 127–138\. doi:10.1016/j.mulfin.2008.09.001.
121. ^ Michael J. Pinegar (2002). "Losing sleep at the market: Comment". American Economic Review. 92 (4): 1251–1256\. doi:10.1257/00028280260344786. JSTOR 3083313. S2CID 16002134.
122. ^ Mark J. Kamstra; Lisa A. Kramer; Maurice D. Levi (2002). "Losing sleep at the market: the daylight saving anomaly: Reply". American Economic Review. 92 (4): 1257–1263\. doi:10.1257/00028280260344795. JSTOR 3083314.
123. ^ Zhang, H.; Khan, A.; Edgren, G.; Rzhetsky, A. (8 June 2020). "Measurable health effects associated with the daylight saving time shift". PLOS Comput. Biol. 16 (6): e1007927. Bibcode:2020PLSCB..16E7927Z. doi:10.1371/journal.pcbi.1007927. PMC 7302868. PMID 32511231.
124. ^ Rishi, M. A.; Ahmed, O.; Barrantes Perez, J. H.; Berneking, J.; Flynn-Evans, E. E.; Gurubhagavatula, I. (2020). "Daylight saving time: an American Academy of Sleep Medicine position statement". Journal of Clinical Sleep Medicine. 16 (10): 1781–1784\. doi:10.5664/jcsm.8780. PMC 7954020. PMID 32844740.
125. ^ Roenneberg T, Wirz-Justice A, Skene DJ, Ancoli-Israel S, Wright KP, Dijk DJ, Zee P, Gorman MR, Winnebeck EC, Klerman EB (2019). "Why Should We Abolish Daylight Saving Time?". Journal of Biological Rhythms. 34 (3): 227–230\. doi:10.1177/0748730419854197. PMC 7205184. PMID 31170882.
126. ^ a b c d e Brian Handwerk (1 December 2013). "Time to Move On? The Case Against Daylight Saving Time". National Geographic News. Archived from the original on 13 March 2014. Retrieved 9 March 2014.
127. ^ Fritz, Josef; VoPham, Trang; Wright, Kenneth P.; Vetter, Céline (February 2020). "A Chronobiological Evaluation of the Acute Effects of Daylight Saving Time on Traffic Accident Risk". Current Biology. 30 (4): 729–735.e2. Bibcode:2020CBio...30E.729F. doi:10.1016/j.cub.2019.12.045. ISSN 0960-9822. PMID 32008905. S2CID 210956409.
128. ^ Orsini, Federico; Zarantonello, Lisa; Costa, Rodolfo; Rossi, Riccardo; Montagnese, Sara (July 2022). "Driving simulator performance worsens after the Spring transition to Daylight Saving Time". iScience. 25 (7): 104666. Bibcode:2022iSci...25j4666O. doi:10.1016/j.isci.2022.104666. ISSN 2589-0042. PMC 9263509. PMID 35811844.
129. ^ Smith, Austin C. (2016). "Spring Forward at Your Own Risk: Daylight Saving Time and Fatal Vehicle Crashes". American Economic Journal: Applied Economics. 8 (2): 65–91\. CiteSeerX 10.1.1.676.1062. doi:10.1257/app.20140100. ISSN 1945-7782.
130. ^ Fritz, Josef (2020). "A Chronobiological Evaluation of the Acute Effects of Daylight Saving Time on Traffic Accident Risk". Current Biology. 30 (4): 729–735.e2. Bibcode:2020CBio...30E.729F. doi:10.1016/j.cub.2019.12.045. PMID 32008905. S2CID 210956409.
131. ^ Jason Varughese; Richard P. Allen (2001). "Fatal accidents following changes in daylight savings time: the American experience". Sleep Medicine. 2 (1): 31–36\. doi:10.1016/S1389-9457(00)00032-0. PMID 11152980.
132. ^ J. Alsousoua; T. Jenks; O. Bouamra; F. Lecky; K. Willett (2009). "Daylight savings time (DST) transition: the effect on serious or fatal road traffic collision related injuries". Injury Extra. 40 (10): 211–212\. doi:10.1016/j.injury.2009.06.241.
133. ^ Tuuli A. Lahti; Jari Haukka; Jouko Lönnqvist; Timo Partonen (2008). "Daylight saving time transitions and hospital treatments due to accidents or manic episodes". BMC Public Health. 8: 74. doi:10.1186/1471-2458-8-74. PMC 2266740. PMID 18302734.
134. ^ Mats Lambe; Peter Cummings (2000). "The shift to and from daylight savings time and motor vehicle crashes". Accident Analysis & Prevention. 32 (4): 609–611\. doi:10.1016/S0001-4575(99)00088-3. PMID 10868764.
135. ^ Sandhu, Amneet; Seth, Milan; Gurm, Hitinder S. (1 March 2014). "Daylight savings time and myocardial infarction". Open Heart. 1 (1): e000019. doi:10.1136/openhrt-2013-000019. ISSN 2053-3624. PMC 4189320. PMID 25332784.
136. ^ Fritz, Josef; VoPham, Trang; Wright Jr., Kenneth P.; Vetter, Céline (30 January 2020). "A Chronobiological Evaluation of the Acute Effects of Daylight Saving Time on Traffic Accident Risk". Current Biology. 30 (4): 729–735.e2. Bibcode:2020CBio...30E.729F. doi:10.1016/j.cub.2019.12.045. PMID 32008905.
137. ^ Manfredini, F.; Fabbian, F.; Cappadona, R. (2018). "Daylight saving time, circadian rhythms, and cardiovascular health". Internal and Emergency Medicine. 13 (5): 641–646\. doi:10.1007/s11739-018-1900-4. PMC 6469828. PMID 29971599.
138. ^ Derks, L.; Houterman, S.; Geuzebroek, G.S.C. (2021). "Daylight saving time does not seem to be associated with number of percutaneous coronary interventions for acute myocardial infarction in the Netherlands". Netherlands Heart Journal. 29 (9): 427–432\. doi:10.1007/s12471-021-01566-7. PMC 8397810. PMID 33765223.
139. ^ a b Cermakian, Nicolas (2 November 2019). "Turn back the clock on Daylight Savings: Why Standard Time all year round is the healthy choice". The Globe and Mail. Archived from the original on 20 October 2020. Retrieved 4 March 2020.
140. ^ a b Block, Gene. "Who wants to go to work in the dark? Californians need Permanent Standard Time". The Sacramento Bee. Archived from the original on 4 March 2020. Retrieved 4 March 2020.
141. ^ a b Antle, Michael (30 October 2019). "Circadian rhythm expert argues against permanent daylight saving time". U Calgary News. Archived from the original on 4 March 2020. Retrieved 4 March 2020.
142. ^ a b "Year-round daylight time will cause 'permanent jet lag,' sleep experts warn in letter to government". CBC News. 31 October 2019. Archived from the original on 8 March 2021. Retrieved 4 March 2020.
143. ^ Barnes, Christopher M.; Drake, Christopher L. (November 2015). "Prioritizing Sleep Health". Perspectives on Psychological Science. 10 (6): 733–737\. doi:10.1177/1745691615598509. PMID 26581727.
144. ^ Tuuli A. Lahti; Sami Leppämäki; Jouko Lönnqvist; Timo Partonen (2008). "Transitions into and out of daylight saving time compromise sleep and the rest–activity cycles". BMC Physiology. 8: 3. doi:10.1186/1472-6793-8-3. PMC 2259373. PMID 18269740.
145. ^ DST and circadian rhythm:
* Pablo Valdez; Candelaria Ramírez; Aída García (2003). "Adjustment of the sleep–wake cycle to small (1–2h) changes in schedule". Biological Rhythm Research. 34 (2): 145–155\. Bibcode:2003BioRR..34..145V. doi:10.1076/brhm.34.2.145.14494. S2CID 83648787.
* Thomas Kantermann; Myriam Juda; Martha Merrow; Till Roenneberg (2007). "The human circadian clock's seasonal adjustment is disrupted by daylight saving time" (PDF). Current Biology. 17 (22): 1996–2000\. Bibcode:2007CBio...17.1996K. doi:10.1016/j.cub.2007.10.025. PMID 17964164. S2CID 3135927. Archived (PDF) from the original on 16 November 2020. Retrieved 6 June 2020.
* "Daylight saving hits late risers hardest". ABC News. Australia. 25 October 2007.
146. ^ Rick Kissell (20 March 2007). "Daylight-saving dock ratings". Variety. Archived from the original on 13 April 2009. Retrieved 20 April 2020.
147. ^ Todd D. Rakoff (2002). A Time for Every Purpose: Law and the Balance of Life. Harvard University Press. p. 26\. ISBN 978-0-674-00910-3.
148. ^ Rachel Pain; Robert MacFarlane; Keith Turner; Sally Gill (2006). "'When, where, if, and but': qualifying GIS and the effect of streetlighting on crime and fear". Environment and Planning A. 38 (11): 2055–2074\. Bibcode:2006EnPlA..38.2055P. doi:10.1068/a38391. S2CID 143511067.
149. ^ Downing, Michael (9 March 2018). "One Hundred Years Later, the Madness of Daylight Saving Time Endures". Smithsonian. Archived from the original on 11 March 2018. Retrieved 12 March 2018. "Today we know that changing the clocks does influence our behavior. For example, later sunset times have dramatically increased participation in afterschool sports programs and attendance at professional sports events. In 1920, The Washington Post reported that golf ball sales in 1918—the first year of daylight saving—increased by 20 percent."
150. ^ Dana Knight (17 April 2006). "Daylight-saving time becomes daylight-spending time for many businesses". Indianapolis Star.
151. ^ Bradley, Barbara (3 April 1987). "For business, Daylight Saving Time is daylight spending time". The Christian Science Monitor.
152. ^ Simon, Eti Ben; Vallat, Raphael; Rossi, Aubrey; Walker, Matthew P. (23 August 2022). "Sleep loss leads to the withdrawal of human helping across individuals, groups, and large-scale societies". PLOS Biology. 20 (8): e3001733. doi:10.1371/journal.pbio.3001733. ISSN 1545-7885. PMC 9398015. PMID 35998121.
153. ^ Cho, Kyoungmin; Barnes, Christopher M.; Guanara, Cristiano L. (13 December 2016). "Sleepy Punishers Are Harsh Punishers". Psychological Science. 28 (2): 242–247\. doi:10.1177/0956797616678437. ISSN 0956-7976. PMID 28182529. S2CID 11321574.
154. ^ Joey Crandall (24 October 2003). "Daylight saving time ends Sunday". Record–Courier. Archived from the original on 29 February 2012.
155. ^ Paul McDougall (1 March 2007). "PG&E says patching meters for an early daylight-saving time will cost $38 million". InformationWeek. Archived from the original on 6 December 2008. Retrieved 13 February 2009.
156. ^ "Daylight saving time: rationale and original idea". 2008. Archived from the original on 9 June 2016. Retrieved 13 February 2009. "... Lord Balfour came forward with a unique concern: 'Supposing some unfortunate lady was confined with twins ...'"
157. ^ "Should we change the clocks?". National Farmers Union. Archived from the original on 14 March 2012. Retrieved 6 January 2012.
158. ^ Crossen, Cynthia (6 November 2003). "Daylight Saving Time Pitted Farmers Against The 'Idle' City Folk". The Wall Street Journal. ISSN 0099-9660. Archived from the original on 28 March 2021. Retrieved 4 December 2020.
159. ^ Effect on those whose hours are set by the sun:
* Spring Forward (2005), pp. 19–33
* Seize the Daylight (2005), pp. 103–110, 149–151, 198
160. ^ Jesse Ruderman (1 November 2006). "Continuous daylight saving time". Archived from the original on 4 May 2016. Retrieved 21 March 2007.
161. ^ "Proposal for a finer adjustment of summer time (daylight saving time)". 28 September 2011. Archived from the original on 8 October 2011. Retrieved 28 September 2011.
162. ^ Albert E. Waugh (1973). Sundials: Their Theory and Construction. Dover. Bibcode:1973sttc.book.....W. ISBN 978-0-486-22947-8.
163. ^ Leith Holloway (1992). "Atmospheric sun protection factor on clear days: its observed dependence on solar zenith angle and its relevance to the shadow guideline for sun protection". Photochemistry and Photobiology. 56 (2): 229–234\. doi:10.1111/j.1751-1097.1992.tb02151.x. PMID 1502267. S2CID 1219032. Archived from the original on 9 August 2020. Retrieved 6 June 2020.
164. ^ Seize the Daylight (2005), p. xv.
165. ^ Daylight saving time and its variants:
* Richard A. Meade (1978). "Language change in this century". English Journal. 67 (9): 27–30\. doi:10.2307/815124. JSTOR 815124.
* Joseph P. Pickett; et al., eds. (2000). "daylight-saving time". The American Heritage Dictionary of the English Language (4th ed.). Boston: Houghton Mifflin. ISBN 978-0-395-82517-4. "or daylight-savings time"
* "daylight saving time". Merriam–Webster's Online Dictionary. Archived from the original on 11 June 2011. Retrieved 13 February 2009. "called also daylight saving, daylight savings, daylight savings time, daylight time"
* "daylight saving time". Oxford Dictionaries. Archived from the original on 22 March 2014. Retrieved 22 March 2014. "also daylight savings time"
* "15 U.S.C. § 260a notes". Archived from the original on 9 November 2021. Retrieved 9 May 2007. "Congressional Findings; Expansion of Daylight Saving Time"
166. ^ Garner, Bryan A. (2000). "daylight saving(s) time". Oxford Dictionary of American Usage and Style. Oxford University Press. p. 95\. ISBN 9780195135084. Archived from the original on 9 November 2021. Retrieved 6 June 2020.
167. ^ "Remember to Put Clocks Hour Ahead on Retiring". Brooklyn Citizen. 25 April 1936. Archived from the original on 8 November 2021. Retrieved 7 November 2021.
168. ^ Steve Lohr (5 March 2007). "Time change a 'mini-Y2K' in tech terms". The New York Times. Archived from the original on 1 February 2017. Retrieved 21 February 2017.
169. ^ A. Gut; L. Miclea; Sz. Enyedi; M. Abrudean; I. Hoka (2006). "Database globalization in enterprise applications". 2006 IEEE International Conference on Automation, Quality and Testing, Robotics. pp. 356–359.
170. ^ Ron Bean (November 2000). "The Clock Mini-HOWTO". Archived from the original on 13 January 2012. Retrieved 10 January 2012.
171. ^ Raymond Chen (November 2000). "Why does Windows keep your BIOS clock on local time?". Archived from the original on 3 January 2012. Retrieved 10 January 2012.
172. ^ Paul Eggert; Arthur David Olson (30 June 2008). "Sources for time zone and daylight saving time data". Archived from the original on 23 June 2012.
173. ^ "tztab(4)" (PDF). HP-UX Reference: HP-UX 11i Version 3. Hewlett–Packard Co. 2010. Archived from the original (PDF) on 21 September 2013.
174. ^ "Other environment variables". IEEE Std 1003.1–2004. The Open Group. 2004. Archived from the original on 6 July 2010. Retrieved 17 February 2007.
175. ^ Rubin, Rita (28 March 2023). "Groundswell Grows for Permanent Daylight Saving Time, but Medical Societies Overwhelmingly Support Year-Round Standard Time". JAMA. 329 (12): 965–967\. doi:10.1001/jama.2023.0159. ISSN 0098-7484.
176. ^ Phillips, Rasheedah (28 January 2025). Dismantling the Master's Clock: On Race, Space, and Time. AK Press. ISBN 978-1-84935-562-9.
177. ^ Parfitt, Tom (25 March 2011). "Think of the cows: clocks go forward for the last time in Russia". The Guardian. Archived from the original on 27 October 2019. Retrieved 5 January 2012.
178. ^ Hollingshead, Iain (June 2006). "Whatever happened to Double Summer Time?". The Guardian. London. Archived from the original on 22 March 2021. Retrieved 18 March 2017.
179. ^ "Russia set to turn back the clocks with daylight-saving time shift". The Guardian. London. 1 July 2014. Archived from the original on 21 December 2016. Retrieved 25 October 2014.
180. ^ "Turkey will not turn back the clock for daylight saving time". Daily Sabah. 7 December 2021. Retrieved 20 September 2022.
181. ^ "Press corner". European Commission. 12 September 2018. Archived from the original on 23 October 2020. Retrieved 23 October 2020.
182. ^ "European parliament votes to scrap daylight saving time from 2021". The Guardian (US ed.). London. 26 March 2019. Archived from the original on 20 June 2019. Retrieved 9 July 2019.
183. ^ "To the EU Commission on DST" (PDF). March 2019. Archived (PDF) from the original on 30 December 2020. Retrieved 4 November 2021.
184. ^ "Seasonal clock change in the EU". Mobility and Transport – European Commission. 22 September 2016. Archived from the original on 30 June 2019. Retrieved 23 October 2020.
185. ^ Posaner, Joshua; Cokelaere, Hanne (24 October 2020). "Stopping the clock on seasonal time changes? Not anytime soon". Politico. Archived from the original on 26 October 2020. Retrieved 26 October 2020.
186. ^ Lawson, Patrick (18 November 2020). "The plan to abolish the time change is "completely blocked" at European level, says specialist in European issues". Geads News. Archived from the original on 12 February 2021.
187. ^ "Fall back! Daylight saving time ends Sunday". USA Today. 1 November 2018. Archived from the original on 2 November 2018. Retrieved 2 November 2018.
188. ^ "Rubio's Bill to Make Daylight Saving Time Permanent Passes Senate". rubio.senate.gov. 15 March 2022. Retrieved 15 June 2022.
189. ^ Haughey, John (18 September 2022). "Time – and money – at stake in Florida-led proposal to extend daylight saving". The Center Square Florida. Retrieved 3 January 2023. "The Florida Chamber of Commerce and state business associations maintain an extra hour of sunlight in the winter, during peak tourist season, would translate into more sales."
190. ^ McLeod, Paul (17 March 2022). "Everyone Was Surprised By The Senate Passing Permanent Daylight Saving Time. Especially The Senators". BuzzFeed. Retrieved 3 January 2023.
191. ^ Schnell, Mychael (25 July 2022). "Permanent daylight saving time hits brick wall in House". The Hill. Retrieved 3 January 2023.
192. ^ Tuccille, J. D. (10 March 2025). "We're overdue to end Daylight Saving Time". Reason.com. Retrieved 11 March 2025.
193. ^ Handwerk, Brian (6 November 2011). "Permanent Daylight Saving Time? Might Boost Tourism, Efficiency". National Geographic. Archived from the original on 9 April 2019. Retrieved 5 January 2012.
194. ^ Team, The Health News (4 November 2022). "Is Daylight Saving Time Good or Bad? | Sharp HealthCare". www.sharp.com. Retrieved 4 December 2024.
195. ^ Kernan, Megan (18 March 2022). "Sleep experts weigh in on Senate approving bill to make Daylight Saving Time permanent". Retrieved 19 September 2022.
196. ^ Roenneberg, Till; Wirz-Justice, Anna; Skene, Debra J; etc. (6 June 2019). "Why Should We Abolish Daylight Saving Time?". Journal of Biological Rhythms. 34 (3): 227–230\. doi:10.1177/0748730419854197. PMC 7205184. PMID 31170882.
197. ^ Roenneberg, Till; Winnebeck, Eva C.; Klerman, Elizabeth B. (7 August 2019). "Daylight Saving Time and Artificial Time Zones – A Battle Between Biological and Social Times". Frontiers in Physiology. 10: 944. doi:10.3389/fphys.2019.00944. PMC 6692659. PMID 31447685.
198. ^ Rishi, Muhammad Adeel; Ahmed, Omer; Barrantes Perez, Jairo H.; etc. (15 October 2020). "Daylight saving time: an American Academy of Sleep Medicine position statement". J Clin Sleep Med. 16 (10): 1781–1784\. doi:10.5664/jcsm.8780. PMC 7954020. PMID 32844740. S2CID 221329004.
199. ^ "American Academy of Sleep Medicine opposes permanent daylight saving time bill". 23 May 2022. Retrieved 3 January 2023.
200. ^ "American Academy of Sleep Medicine calls for elimination of daylight saving time". 27 August 2020. Retrieved 3 January 2023.
201. ^ Davies, Claire (14 March 2021). "Sleep Awareness Week 2021: Over 70% say daylight saving time change doesn't affect sleep". TopTenReviews. Retrieved 11 January 2023.
202. ^ a b "States Object to Changing the Clocks for Daylight Saving Time". Almanac.com. 6 January 2023. Retrieved 7 January 2023.
203. ^ "Daylight Saving Time: Americans want to stay permanently 'sprung forward' and not 'fall back' | YouGov". today.yougov.com. Retrieved 9 January 2023.
204. ^ "Daylight Saving Time vs Standard Time". 2019. Retrieved 7 January 2023.
205. ^ "Dislike for changing the clocks persists". 2021. Retrieved 7 January 2023.
206. ^ Ripley, Anthony (1 October 1974). "Senate Votes Return to Standard Time For Four Months and Sends Bill to Ford". The New York Times. Retrieved 7 January 2023.

### Sources

[edit]

* Michael Downing (2005). Spring Forward: The Annual Madness of Daylight Saving Time. Shoemaker & Hoard. ISBN 978-1-59376-053-3.
* David Prerau (2005). Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time. Thunder's Mouth Press. ISBN 978-1-56025-655-7. The British version, focusing on the UK, is Saving the Daylight: Why We Put the Clocks Forward. Granta Books. ISBN 978-1-86207-796-6.

## Further reading

[edit]

* Ian R. Bartky (2007). One Time Fits All: The Campaigns for Global Uniformity. Stanford University Press. ISBN 978-0804756426.

## External links

[edit]

Listen to this article (39 minutes)

This audio file was created from a revision of this article dated 20 May 2008 (2008-05-20), and does not reflect subsequent edits.

(Audio help · More spoken articles)

Wikimedia Commons has media related to Daylight saving time.

* Daylight Saving Time Congressional Research Service
* Information about the Current Daylight Saving Time (DST) Rules, U.S. National Institute of Standards and Technology
* "Legal Time 2015", Telecommunications Standardization Bureau of the ITU
* Sources for time zone and daylight saving time data
* Use of Changing Times Around the World

* v
* t
* e

Time measurement and standards

* Chronometry
* Orders of magnitude
* Metrology

International standards|

* Coordinated Universal Time
* offset
* UT
* ΔT
* DUT1
* International Earth Rotation and Reference Systems Service
* ISO 31-1
* ISO 8601
* International Atomic Time
* 12-hour clock
* 24-hour clock
* Barycentric Coordinate Time
* Barycentric Dynamical Time
* Civil time
* Daylight saving time
* Geocentric Coordinate Time
* International Date Line
* IERS Reference Meridian
* Leap second
* Solar time
* Terrestrial Time
* Time zone
* 180th meridian

Obsolete standards|

* Ephemeris time
* Greenwich Mean Time
* Prime meridian

Time in physics|

* Absolute space and time
* Spacetime
* Chronon
* Continuous signal
* Coordinate time
* Cosmological decade
* Discrete time and continuous time
* Proper time
* Theory of relativity
* Time dilation
* Gravitational time dilation
* Time domain
* Time-translation symmetry
* T-symmetry

Horology|

* Clock
* Astrarium
* Atomic clock
* Complication
* History of timekeeping devices
* Hourglass
* Marine chronometer
* Marine sandglass
* Radio clock
* Watch
* stopwatch
* Water clock
* Sundial
* Dialing scales
* Equation of time
* History of sundials
* Sundial markup schema

Calendar|

* Gregorian
* Hebrew
* Hindu
* Holocene
* Islamic (lunar Hijri)
* Julian
* Solar Hijri
* Astronomical
* Dominical letter
* Epact
* Equinox
* Intercalation
* Julian day
* Leap year
* Lunar
* Lunisolar
* Solar
* Solstice
* Tropical year
* Weekday determination
* Weekday names

Archaeology and geology|

* Chronological dating
* Geologic time scale
* International Commission on Stratigraphy

Astronomical chronology|

* Galactic year
* Nuclear timescale
* Precession
* Sidereal time

Other units of time|

* Instant
* Flick
* Shake
* Jiffy
* Second
* Minute
* Moment
* Hour
* Day
* Week
* Fortnight
* Month
* Year
* Olympiad
* Lustrum
* Decade
* Century
* Saeculum
* Millennium

Related topics|

* Chronology
* Duration
* music
* Mental chronometry
* Decimal time
* Metric time
* System time
* Time metrology
* Time value of money
* Timekeeper

* v
* t
* e

Coordinated Universal Time (UTC)

UTC offset for standard time and Daylight saving time (DST)

Italics: historical or unofficial|

| 180° to 90°W|

* −12:00
* −11:00
* −10:30
* −10:00
* −09:30
* −09:00
* −08:30
* −08:00
* −07:00

|

90°W to 0°|

* −06:00
* −05:00
* −04:30
* −04:00
* −03:30
* −03:00
* −02:30
* −02:00
* −01:00
* −00:44
* −00:25:21

0° to 90°E|

* +00:00
* +00:20
* +00:30
* +01:00
* +01:24
* +01:30
* +02:00
* +02:30
* +03:00
* +03:30
* +04:00
* +04:30
* +04:51
* +05:00
* +05:30
* +05:40
* +05:45

90°E to 180°|

* +06:00
* +06:30
* +07:00
* +07:20
* +07:30
* +08:00
* +08:30
* +08:45
* +09:00
* +09:30
* +09:45
* +10:00
* +10:30
* +11:00
* +11:30

180° to 90°W|

* +12:00
* +12:45
* +13:00
* +13:45
* +14:00

Time zone data sources|

tz database

Lists of time zones|

* Time zones by country
* Time zones by UTC offset
* Military time zone
* Time zone abbreviations
* Daylight saving time by country

Related topics|

* Abolition of time zones

* v
* t
* e

Daylight saving time (or summer time)

By continent|

* Daylight saving time in Africa
* Daylight saving time in Asia
* Daylight saving time in the Americas
* Summer time in Europe
* Daylight saving time in Oceania

Overviews|

* Daylight saving time by country

Authority control databases

National|

* Germany
* United States
* Japan
* Czech Republic
* Israel

Other|

* NARA

*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template