Daylight Saving Time

Seasonal change of clock settings

“DST”, “Daylight savings”, and “Summer time” redirect here. For the film, see Daylight Savings (film) . For the season, see Summer . For other uses, see DST (disambiguation) and Summertime .

Daylight saving time regions:   Northern Hemisphere summer

•   Southern Hemisphere summer

•   Formerly used daylight saving

•   Never used daylight saving

Daylight saving time (DST), also frequently referred to as daylight savings time, daylight time (United States and Canada ), or summer time (United Kingdom , European Union , and many other regions), is a practice of advancing clocks forward by a set amount during warmer months to make better use of the longer daylight hours available in the summer . The intention is that darkness will fall at a later clock time, allowing for increased activity in the evening. The most common implementation of DST involves setting clocks forward by one hour in the spring or late winter, and then setting them back by one hour to revert to standard time in the autumn (or fall, as it’s known in North American English, hence the popular mnemonic : “spring forward and fall back”).

It’s worth noting that in a significant number of countries, the period during which DST is observed is considerably longer than the period dedicated to standard time.

Overview

As of the most recent comprehensive data available, approximately 34 percent of the world’s countries observe DST, with the practice being most prevalent in Europe and North America. Some nations implement DST only in specific regions, rather than nationwide. For instance, Canada largely adheres to DST, with notable exceptions in Yukon , the majority of Saskatchewan , and portions of Nunavut , British Columbia , and Quebec . Australia observes DST in four of its states and one territory. Within the United States , DST is observed by almost all states, with the exceptions of Hawaii and Arizona (though, intriguingly, the Navajo Nation , located within Arizona, does observe it), and all of its U.S. Territories .

Historically, there are accounts of ancient societies adopting seasonal adjustments to their timekeeping to better align with daylight. The Roman timekeeping system, for example, even incorporated variations in water clocks to account for the changing lengths of daylight hours. However, these adjustments were primarily modifications to the divisions of the day itself, rather than a wholesale advancement of the entire clock forward. In a rather satirical piece penned in 1784 for the Journal de Paris , Benjamin Franklin humorously suggested that if Parisians simply woke up earlier during the summer, they would naturally economize on their use of candles and oil. Yet, he did not propose altering the clocks themselves. The first truly practical proposal for a clock adjustment came in 1895 from New Zealand entomologist and astronomer George Hudson . He presented a concept to the Wellington Philosophical Society advocating for a two-hour clock shift each spring. While this specific proposal wasn’t enacted immediately, a modified version was eventually adopted much later, in 1928. Independently, in 1907, William Willett put forth his own proposal for the adoption of what would become British Summer Time , primarily as a measure to conserve energy. This idea garnered serious consideration in Parliament but wasn’t implemented until 1916.

The very first practical implementation of DST occurred in 1908, not on a national scale, but locally in Port Arthur, Ontario (which has since merged into Thunder Bay ). The first nation-wide adoptions of DST were by the German Empire and the Austro-Hungarian Empire in 1916, specifically on April 30th. Since then, a multitude of countries have integrated DST into their timekeeping practices at various junctures, with a notable surge in adoption following the 1970s energy crisis .

Rationale

An ancient water clock illustrating variable hour lengths based on season.

Societies that operate on an industrialized, clock-based schedule typically maintain fixed times for daily activities like work and school, regardless of the season. Public transportation schedules, for instance, are usually designed around these constant timings. In stark contrast, agrarian societies have historically based their daily routines more directly on the prevailing solar time and the duration of daylight, which naturally fluctuate with the seasons due to the Earth’s axial tilt . Regions situated north and south of the tropics experience longer daylight hours during their respective summers and shorter days in their winters. The further one moves from the equator , the more pronounced this seasonal variation in daylight becomes. Consequently, DST offers minimal benefit to regions located very near the Equator, where the variation in daylight hours throughout the year is negligible.

When clocks are advanced in a region as DST begins in spring, anticipating longer daylight, individuals adhering to a clock-based schedule are effectively awakened an hour earlier relative to the solar day than they would have been otherwise. Their workdays commence and conclude an hour earlier, and crucially, they gain an additional hour of daylight after their typical work obligations are met. This shift is, in part, a matter of practicality. Consider, for example, the temperate latitudes of North America during the summer solstice. The sun might rise as early as 04:30 by standard time, and set around 19:30. Since most people are asleep at 04:30, shifting the clock forward by an hour makes it appear as though the sun rises at 05:30 and sets at 20:30. This adjustment aligns waking hours more closely with natural light and provides an extra hour of daylight for evening activities.

Proponents of daylight saving time often argue that the majority of people prefer to have more usable daylight hours available after their typical “nine to five ” workday concludes. Supporters have also posited that DST leads to reduced energy consumption by decreasing the need for artificial lighting and, to some extent, heating. However, the actual impact of DST on overall energy usage is a subject of considerable debate and conflicting research. A thorough evaluation requires looking beyond just lighting demand and also considering the energy used for heating and cooling buildings.

Variation within a Time Zone

The effectiveness and experience of daylight saving time can also differ based on a location’s position within its time zone . Areas situated further east within a given time zone tend to benefit more from DST than those located towards the western edge of the same zone.

History

Ancient civilizations possessed a more fluid approach to adjusting daily schedules to the sun than DST currently allows, often dividing daylight into 12 hours irrespective of the actual duration, meaning daylight hours naturally lengthened in spring and shortened in autumn. For instance, Romans kept time using water clocks that featured different scales for each month. At Rome’s latitude, the third hour after sunrise ( hora tertia ) began at approximately 09:02 solar time and lasted about 44 minutes during the winter solstice . However, at the summer solstice, this same hour commenced at 06:58 and extended to 75 minutes. From the 14th century onwards, the use of equal-length civil hours gradually supplanted these unequal, seasonally varying hours, rendering civil time independent of seasonal changes. Unequal hours, however, persist in a few traditional contexts, such as in certain monasteries on Mount Athos and within Jewish religious observances.

Benjamin Franklin , in his famous adage, “early to bed and early to rise makes a man healthy, wealthy, and wise,” also published a letter in the Journal de Paris during his tenure as the American envoy to France (1776–1785). In this satirical piece, he humorously suggested that Parisians could save on candle expenditures by waking earlier to utilize the morning sunlight. This 1784 essay playfully proposed measures such as taxing window shutters, rationing candles, and rousing the public with church bells and cannon fire at dawn. Contrary to a common misconception, Franklin did not actually propose DST; furthermore, 18th-century Europe did not operate on the precise schedules that characterize modern life. This changed dramatically with the advent of rail transport and sophisticated communication networks, which necessitated a standardization of clocks far beyond what was conceivable in Franklin’s era.

In 1810, the Spanish National Assembly, known as the Cortes of Cádiz , enacted a regulation that advanced certain meeting times by one hour between May 1st and September 30th, acknowledging the seasonal shifts in daylight. However, this regulation did not involve changing the clocks themselves. It also recognized the existing practice of private businesses voluntarily adjusting their opening hours to align with daylight conditions.

George Hudson made the first proposal for modern DST in 1895.

New Zealand entomologist George Hudson is credited with the first proposal for modern DST. His occupation, which involved shift work, afforded him ample spare time for collecting insects, during which he came to appreciate the extended daylight available after his working hours. In 1895, he presented a paper to the Wellington Philosophical Society outlining his idea for a two-hour daylight-saving shift. This concept generated considerable interest in Christchurch , and he followed up with another paper in 1898. It is worth noting that many historical accounts credit the DST proposal to the prominent English builder and outdoorsman William Willett . Willett independently conceived of DST in 1907 during a morning ride, observing how many Londoners appeared to sleep through a significant portion of the summer day. Willett, an avid golfer, also found his rounds curtailed by dusk. His proposed solution was to advance the clocks during the summer months, and he published this idea two years later. The proposal was championed by Liberal Party Member of Parliament Robert Pearce , who introduced the first Daylight Saving Bill to the British House of Commons on February 12, 1908. A select committee was formed to investigate the matter, but Pearce’s bill did not pass into law, and several subsequent attempts also failed. Willett continued to advocate for the proposal in the UK until his death in 1915.

DST was first implemented in the United States as a measure to conserve energy during World War I. The poster here is from United Cigar Stores .

The first city in the world to officially adopt DST was Port Arthur, Ontario, Canada , on July 1, 1908. This was soon followed by Orillia, Ontario , where DST was introduced by Mayor William Sword Frost during his tenure from 1911 to 1912. The first nations to implement DST (in German, Sommerzeit) were the German Empire and its World War I ally, Austria-Hungary , beginning on April 30, 1916. This was primarily motivated by the need to conserve coal supplies during wartime. Britain, along with most of its allies and several neutral European nations, followed suit shortly thereafter. Russia and a few other countries waited until the following year, and the United States adopted daylight saving in 1918. Many jurisdictions subsequently abandoned DST in the years following the end of the war in 1918, though exceptions included Canada, the United Kingdom, France, Ireland, and the United States. DST saw a resurgence in use during World War II (with some countries even adopting double summer time), and it was standardized nationally in the US by federal law in 1966. Its widespread adoption in Europe gained momentum from the 1970s, largely in response to the 1970s energy crisis . Since then, DST has seen numerous enactments, adjustments, and repeals across the globe.

It is a widely circulated myth in the United States that DST was initially implemented to benefit farmers. In reality, farmers have historically been among the most vocal and organized groups opposing DST since its inception. The schedules of agricultural work are fundamentally dictated by natural phenomena like morning dew and the biological rhythms of dairy cattle , which are not influenced by clock changes. Consequently, the artificial shift in time introduces unnecessary complications and challenges for farming operations.

DST was first introduced in the US via the Standard Time Act of 1918. This was a wartime measure, implemented for seven months to extend daylight hours and conserve energy resources. Year-round DST, often referred to as “War Time ”, was reinstated during World War II. Post-war, individual local jurisdictions retained the discretion to observe DST or not, until the passage of the Uniform Time Act , which standardized DST practices nationwide in 1966. A more recent attempt at permanent daylight saving time was enacted by President Richard Nixon in January 1974. However, this proved highly unpopular due to widespread complaints about children attending school in darkness and workers commuting in pitch black during the winter months. By October 1974, President Gerald Ford signed legislation repealing the year-round daylight savings time.

Procedure

• See also: Daylight saving time by country

When DST observation commences, clocks are typically advanced by one hour in the early morning hours.

When DST observation concludes and standard time resumes, clocks are turned back by one hour, also usually in the early morning.

The precise timing of these clock changes varies significantly depending on the specific jurisdiction.

Authorities responsible for timekeeping generally schedule these transitions to occur at or shortly after midnight on a weekend. This timing is intended to minimize disruption to weekday work and school schedules. While a one-hour shift is the most common practice today, historical instances of twenty-minute and even two-hour shifts have been recorded. Notable contemporary exceptions include Lord Howe Island , which observes a thirty-minute shift, and the Troll research station in Antarctica, which has shifted its clocks by two hours directly between CEST and GMT since 2016.

In virtually all countries that observe daylight saving time seasonally (meaning it applies during summer but not winter), the clock is advanced from standard time to daylight saving time in the spring. Conversely, it is turned back from daylight saving time to standard time in the autumn.

If a midnight transition occurs in spring, a digital clock would appear to jump from 23:59:59.9 to 01:00:00.0. For the same clock during the autumn transition, the local time would effectively repeat the hour preceding midnight, jumping from 23:59:59.9 back to 23:00:00.0.

In most countries that observe seasonal daylight saving time, clocks revert to standard time during the winter months. An interesting exception is Ireland, where its winter clock setting (UTC+00:00 ) shares the same offset and legal designation as Greenwich Mean Time in Britain. However, while its summer clock setting also matches Britain’s offset (UTC+01:00 ), its legal name is curiously referred to as Irish Standard Time, rather than the more intuitive British Summer Time .

Since 2019, Morocco has observed daylight saving time throughout the year, with the exception of the month of Ramadan . During Ramadan, the date of which shifts annually according to the lunar calendar and thus moves relative to the Gregorian calendar , the country’s civil clocks align with Western European Time (UTC+00:00), which geographically covers most of the nation. Upon the conclusion of Ramadan, its clocks are then advanced to Western European Summer Time (UTC+01:00).

The exact times at which clocks are changed vary considerably between different jurisdictions. Member states of the European Union coordinate their clock changes, ensuring all time zones transition simultaneously at 01:00 Coordinated Universal Time (UTC). This means the change occurs at 02:00 Central European Time (CET), which is equivalent to 03:00 Eastern European Time (EET). Consequently, the time differences between European time zones remain constant throughout the year. The coordination of clock changes in North America differs; here, each jurisdiction adjusts its local clock at 02:00, which temporarily creates a one-hour time difference with the adjacent time zone until it too makes its adjustment one hour later. For example, during the spring transition, Mountain Time is momentarily two hours ahead of Pacific Time instead of the usual one hour. Similarly, in the autumn, it briefly becomes zero hours ahead of Pacific Time before the next zone adjusts.

The specific dates on which clocks change vary by location and year, leading to fluctuations in time differences between regions throughout the year. For instance, Paris (which operates on Central European Time) is typically six hours ahead of New York City (which uses North American Eastern Time ), except for a few weeks in March and October/November when this difference narrows to five hours. Paris and Santiago maintain a six-hour difference during the northern hemisphere’s summer, but this shrinks to four hours during the southern hemisphere’s summer, with a few weeks each year where the difference is five hours. Since 1996, European Summer Time has been observed from the last Sunday in March to the last Sunday in October. Prior to this directive, the rules for DST transitions were not uniform across all European Union member states. Starting in 2007, most of the United States and Canada adopted a DST schedule running from the second Sunday in March to the first Sunday in November, encompassing nearly two-thirds of the year. Furthermore, the start and end dates for DST are roughly reversed between the northern and southern hemispheres due to the six-month displacement of spring and autumn. For example, mainland Chile observes DST from the second Saturday in October to the second Saturday in April, with transitions occurring at the local clock’s 24:00 . In some countries, clock changes are governed by regional jurisdictions, meaning some areas within a country may change their clocks while others do not. This is currently the case in Australia, Canada, and the United States.

From year to year, the dates for clock changes can also be influenced by political or social considerations. The Uniform Time Act of 1966 established a standard DST period of six months in the United States (previously, it was locally determined). This period was extended to seven months in 1986 and subsequently to eight months in 2005. The 2005 extension was partly driven by lobbying efforts from the candy industry, which sought to capitalize on the inclusion of Halloween (October 31st) within the DST period to potentially increase sales. In more recent history, Australian state jurisdictions have not only changed clocks at different local times but sometimes on different dates. For example, in 2008, most states observing DST advanced their clocks on October 5th, while Western Australia made the change on October 26th.

Politics, Religion, and Sports

The very concept of daylight saving time has been a source of controversy since its earliest proposals. Winston Churchill , for instance, argued that it expanded “the opportunities for the pursuit of health and happiness among the millions of people who live in this country.” Conversely, some commentators have derisively dubbed it “Daylight Slaving Time.” Historically, retail, sports, and tourism industries have generally favored DST, while agricultural sectors and those involved in evening entertainment—along with some religious groups—have opposed it. Energy crises and wartime necessities, however, often prompted its initial adoption.

Willett’s 1907 proposal serves as a prime example of the political complexities involved. It garnered significant support from influential figures, including Arthur Balfour , Churchill himself, David Lloyd George , Ramsay MacDonald , King Edward VII (who personally used a half-hour DST, or “Sandringham time ”, at his Sandringham estate), the managing director of Harrods , and the manager of the National Bank Ltd. However, opposition proved formidable, comprising figures such as Prime Minister H. H. Asquith , William Christie (the Astronomer Royal ), George Darwin , Napier Shaw (director of the Meteorological Office), numerous agricultural organizations, and theatre owners. Following extensive hearings, a parliamentary committee narrowly rejected the proposal in 1909. Willett’s allies continued to introduce similar bills annually from 1911 through 1914, but without success. In the United States, public skepticism was even more pronounced. Andrew Peters introduced a DST bill to the House of Representatives in May 1909, but it quickly faltered in committee.

Retailers have generally been strong proponents of DST; United Cigar Stores , for example, actively promoted a 1918 DST bill.

Germany and its allies took the lead in implementing DST during World War I on April 30, 1916. Their primary objective was to alleviate hardships caused by wartime coal shortages and to improve visibility during air-raid blackouts. The political landscape shifted in other nations; the United Kingdom adopted DST shortly thereafter, on May 21, 1916. In the US, lobbying efforts by American retail and manufacturing interests, spearheaded by Pittsburgh industrialist Robert Garland, soon began advocating for DST, though railroads initially opposed the idea. The US entry into the war in 1917 ultimately tipped the scales, overcoming objections, and DST was implemented in 1918.

The conclusion of World War I brought about a significant change in DST practices. Farmers, who consistently disliked the time shift, were influential in many countries repealing DST. Germany itself, for instance, abandoned DST from 1919 to 1939 and again from 1950 to 1979. Britain, however, proved an exception, retaining DST nationwide but adjusting its transition dates over the years for various reasons, including special provisions during the 1920s and 1930s to avoid clock shifts falling on Easter mornings. As of 2009, summer time began annually on the last Sunday in March, in accordance with a European Community directive, which could occasionally coincide with Easter Sunday (as it did in 2016). In the US, Congress repealed DST after 1919. President Woodrow Wilson , an avid golfer much like Willett, vetoed the repeal twice, but his second veto was ultimately overridden. Only a handful of US cities maintained DST locally, including New York (to preserve an hour of arbitrage trading with London on its financial exchanges), as well as Chicago and Cleveland (to maintain parity with New York’s trading hours). Wilson’s successor, President Warren G. Harding , expressed skepticism towards DST, referring to it as a “deception” and suggesting that individuals should simply adjust their waking and working hours earlier in the summer. He even directed federal employees in the District of Columbia to commence work at 8 am instead of 9 am during the summer of 1922. While some businesses followed suit, many did not, and the experiment was not repeated.

Since Germany’s initial adoption of DST in 1916, the world has witnessed numerous instances of its implementation, modification, and repeal, often accompanied by similar political debates. The history of time in the United States includes DST during both world wars , but a nationwide standardization of peacetime DST was not achieved until 1966. In a peculiar instance in May 1965, St. Paul and Minneapolis, Minnesota , observed different times for two weeks: the state capital decided to switch to DST, while Minneapolis opted to adhere to the later date specified by state law. During the mid-1980s, the primary financial backing for the Daylight Saving Time Coalition, which advocated for the 1987 extension of US DST, came from Clorox and 7-Eleven . Senators from Idaho , Larry Craig and [Mike Crapo], reportedly voted in favor based on the premise that fast-food restaurants sell more French fries (a product of Idaho potatoes) during DST.

A referendum on the introduction of daylight saving was held in Queensland, Australia , in 1992, following a three-year trial period. The referendum was defeated, with 54.5% voting against DST. Opposition was particularly strong in regional and rural areas, while metropolitan southeastern Queensland favored its continuation.

In 2003, the United Kingdom’s Royal Society for the Prevention of Accidents supported a proposal to observe year-round daylight saving time. However, this initiative faced opposition from various industries, postal workers, farmers, and notably, from residents of the northern regions of the UK.

In 2005, the Sporting Goods Manufacturers Association and the National Association of Convenience Stores successfully lobbied for the extension of US DST that took effect in 2007.

In December 2008, the Daylight Saving for South East Queensland (DS4SEQ) political party was formally registered in Queensland. This party advocated for the implementation of a dual-time-zone arrangement for DST in South East Queensland , while the rest of the state would continue to observe standard time. DS4SEQ fielded 32 candidates in the March 2009 Queensland state election, securing one percent of the statewide primary vote , which translated to approximately 2.5% in the 32 electorates where they contested seats. Following a three-year trial, over 55% of Western Australians voted against DST in 2009, with rural areas expressing strong opposition. Queensland Independent member Peter Wellington introduced the Daylight Saving for South East Queensland Referendum Bill 2010 into the Queensland parliament on April 14, 2010. This action was prompted by the DS4SEQ political party, and the bill called for a referendum at the next state election on the introduction of DST in South East Queensland under a dual-time-zone system. The Queensland parliament ultimately rejected Wellington’s bill on June 15, 2011.

In 2011, Russia declared its intention to remain on DST year-round (UTC+4:00 ), a move subsequently mirrored by Belarus. (It is worth noting that the Soviet Union had previously operated under permanent “summer time” from 1930 until at least 1982.) Russia’s plan, however, led to widespread public dissatisfaction due to the exceptionally late sunrises during the winter months. Consequently, this policy was abandoned in 2014. The country reverted to standard time (UTC+3:00 ) on October 26, 2014, with the intention of permanently staying on this time.

In the United States, Arizona (excluding 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 observe daylight saving time. Indiana only began participating in DST as recently as 2006. Between 2018 and 2024, Senator Marco Rubio (R-FL) repeatedly introduced legislation to make DST permanent throughout the year, but these efforts did not succeed.

Mexico observed summertime daylight saving time starting in 1996. However, in late 2022, the nation’s clocks were set back for the final time, restoring permanent standard time across the country.

Religion

Certain religious groups and individuals have voiced opposition to DST on religious grounds. For observant Muslims and Jews, the practice can complicate or inconvenience religious observances such as prayer and fasting rituals. [104] [71] [72] [73] Some Muslim-majority countries, Morocco among them, have temporarily suspended DST during the month of Ramadan. [73]

In Israel, DST has been a recurring point of contention between religious and secular segments of the population, leading to variations in its observance over the years and a shorter DST period compared to the EU and US. Religious Jews generally prefer a shorter DST period [a] because it can delay scheduled morning prayers , potentially conflicting with standard working hours and business schedules . Furthermore, DST is typically ended before Yom Kippur , a significant 25-hour fast day that begins and ends at sunset and involves extensive synagogue prayer. The later end of the day under DST is considered by many to make the observance more challenging. [b] [71] [105]

In the US, Orthodox Jewish organizations have expressed opposition to extensions of DST, [106] including a bipartisan bill introduced in 2022 [107] that aimed to make DST permanent. Their stated concern is that it would “interfere with the ability of members of our community to engage in congregational prayers and get to their places of work on time.” [72]

Effects

• Main article: Analysis of daylight saving time

Effects on Electricity Consumption

William Willett , who independently proposed DST in 1907, tirelessly advocated for its adoption. [108]

Advocates of DST generally argue that it leads to energy savings, encourages outdoor leisure activities in the evening (during summer), and consequently benefits physical and psychological health. [109] They also often cite reduced traffic accidents, decreased crime rates, and positive impacts on business as additional benefits. [110] Conversely, opponents contend that the actual energy savings are inconclusive or negligible. [111]

While energy conservation remains a stated goal under certain conditions, [112] the patterns of energy consumption have undergone significant transformations. Projections for 2025 suggest that, due to these evolving consumption patterns, particularly the increased use of air conditioning systems, additional energy consumption is likely to occur more frequently during daylight saving time in the future. [113] Electricity usage is profoundly influenced by factors such as geography, climate, and economic conditions, meaning that the findings of studies conducted in one location may not be directly applicable to other countries or climates. [114] Nevertheless, even if overall electricity consumption does not decrease, DST has been shown to flatten the evening peak demand, which in turn directly impacts electricity generation costs. [113]

A comprehensive meta-analysis conducted in 2017, examining 44 different studies, concluded that DST results in electricity savings of approximately 0.3% on the days it is observed. [115] [116] Some studies have indicated that DST might lead to an increase in motor fuel consumption, [114] but a 2008 report by the United States Department of Energy found no significant increase in motor gasoline consumption attributable to the 2007 extension of DST in the United States. [117] An initial objective of DST was to reduce the evening usage of incandescent lighting , which was once a primary driver of electricity consumption. [118]

Economic Effects

It has been argued that the biannual clock shifts correlate with a decrease in economic efficiency . For example, one study estimated that in 2000, the daylight-saving effect resulted in an estimated one-day loss of $31 billion on US stock exchanges. [119] Other researchers, however, have asserted that these observed results are dependent on methodology [120] and have disputed the findings, [121] although the original authors have defended their conclusions against these critiques. [122]

Effects on Health

Measurable adverse health effects have been linked to the biannual clock shifts associated with DST. [123] Research indicates that DST disrupts human circadian rhythms , [124] negatively impacting overall human health. [125] The annual DST clock shifts have been associated with increased health risks, including a higher incidence of heart attacks [126] and traffic accidents. [127] [128]

A 2017 study published 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 attributed to increased sleep deprivation. [129]

A study conducted by the London School of Economics (LSE) found that the transition into DST increases individuals’ feelings of being rushed and reduces the time spent on leisure activities by approximately 10 minutes. Specifically, the spring transition into DST was found to decrease life satisfaction by around 1.44 percent. The study also indicated that respondents reported getting less sleep on the first day following the transition, which in turn affected their individual productivity. [130]

A correlation between clock shifts and an increase in traffic collisions has been observed in North America and the UK, though not consistently in Finland or Sweden. [131] Four separate reports have suggested that this effect, while present, is smaller than the overall reduction in traffic fatalities achieved through other safety measures. [132] [133] [134] [135] Data shared by Titan Casket indicates a concerning trend: hospitals report a 24% increase in heart attacks [136] and a 6% rise in fatal crashes [137] each year following the time change. In 2018, the European Parliament , while reviewing a potential abolition of DST, approved a more detailed evaluation focusing on the disruption of the human body’s circadian rhythms. This review provided evidence suggesting a link between DST clock shifts and a modest increase in the occurrence of acute myocardial infarction, particularly in the week following the spring transition. [138] However, a study conducted in the Netherlands reported findings contrary to the majority of investigations, indicating either no effect or a minimal impact. [139] Some experts and organizations advocate for year-round standard time (as opposed to year-round DST) as the preferable option for public health and safety. [140] [141] [142] [143] [144] Clock shifts have been found to elevate the risk of heart attack by 10 percent [126] and to disrupt sleep patterns, reducing its efficiency. [145] The seasonal adaptation of the circadian rhythm can be severely impacted, with effects lasting for weeks. [146]

In 2025, a Stanford study compared the year-long circadian health impacts of permanent Standard Time, permanent Daylight Saving Time, and the current biannual switching system across the continental US. Using models of the human circadian rhythm and health data from the CDC Places dataset, researchers predicted that a shift to permanent Standard Time would lead to a reduction of 2.6 million cases of obesity and 300,000 cases of stroke. Permanent Daylight Saving Time also showed positive health outcomes, though to a lesser extent. The study’s authors cautioned in interviews that this research focused specifically on circadian health and that other factors, such as economic and safety implications, should be considered in policy decisions regarding time. [147]

Effects on Social Relations

DST has been observed to negatively impact prime-time television broadcast ratings, [148] [126] as well as attendance at drive-in theaters and other cinematic venues. [149] The influence of artificial outdoor lighting on crime rates and the perception of crime is considered marginal and sometimes contradictory. [150]

The later sunsets brought about by DST are thought to influence behavior in several ways. For example, they may increase participation in after-school sports programs or outdoor afternoon activities like golf, and boost attendance at professional sporting events. [151] Proponents of daylight saving time argue that the availability of more daylight hours between the end of a typical workday and evening encourages increased consumption of goods and services. [152] [110] [153]

In 2022, a publication detailing three replicating studies—examining individuals, interpersonal dynamics, and societal-level trends—demonstrated that sleep loss negatively affects the human motivation to help others. Functional magnetic resonance imaging (fMRI ) findings indicated “deactivation of key nodes within the social cognition brain network that facilitates prosociality.” Furthermore, by analyzing over three million real-world charitable donations, the researchers detected that the sleep deprivation induced by the transition to daylight saving time led to a reduction in altruistic giving compared to control states that did not implement DST. They concluded that the effects on civil society are “non-trivial.” [154]

Another study, which also investigated sleep disruption caused by the spring shift to daylight saving time, analyzed archival data from US federal courts. This analysis revealed that judges experiencing sleep deprivation tended to impose more severe penalties. [155]

Inconvenience

The biannual clock shifts associated with DST introduce a degree of complexity and inconvenience. Individuals must remember to manually adjust their clocks, which can be a time-consuming task, particularly for older mechanical clocks that cannot be safely moved backward. [156] Those who work across different time zones face the added burden of tracking multiple DST rules, as not all locations observe DST, or they may observe it differently. The length of a calendar day becomes variable, no longer consistently equaling 24 hours. Disruptions to meetings, travel plans, broadcast schedules, billing systems, and record-keeping are common occurrences and can incur significant costs. [157] During the autumn transition, when clocks move from 02:00 back to 01:00, the clock displays local times from 01:00:00 through 01:59:59 twice, which can lead to confusion. [158]

Many farmers express strong opposition to DST, especially dairy farmers , whose cows’ milking schedules are dictated by biological rhythms rather than the clock. [126] [159] [160] Similarly, others whose work hours are intrinsically tied to the sun find DST disruptive. [161] Concerns are also frequently raised about schoolchildren who may be exposed to darkness during their morning commutes due to later sunrises. [126]

Remediation

Some of the complications arising from clock shifts could theoretically be mitigated by adjusting clocks continuously [162] or, at the very least, more gradually [163] —for example, Willett initially proposed weekly 20-minute transitions. However, such approaches would introduce their own complexities and have never been implemented. DST inherently inherits and can even amplify the disadvantages associated with standard time. For instance, when reading a sundial , one must now account for DST in addition to time zone differences and natural discrepancies. [164] Likewise, guidelines for sun exposure, such as avoiding direct sun within two hours of noon, become less accurate when DST is in effect. [165]

Terminology

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”) had already become significantly more common than the older form “daylight saving time” in American English by 1978, with Meade noting that “the change has been virtually accomplished.” Nevertheless, major dictionaries such as Merriam-Webster’s , American Heritage , and Oxford , which typically document actual usage rather than prescribe outdated norms (and therefore also list the newer form), still prioritize the older form. This preference stems from the fact that “daylight saving time” remains prevalent in print and is favored by many editors. The dictionaries often include notes like: “Although daylight saving time is considered correct, daylight savings time (with an ’s’) is commonly used.” The initial two words are sometimes hyphenated, appearing as “daylight-saving(s) time.” Merriam-Webster’s also lists the forms “daylight saving,” “daylight savings” (both without “time”), and “daylight time.” The Oxford Dictionary of American Usage and Style elaborates on the evolution and current status:

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. [168]

In Britain, Willett’s 1907 proposal [34] used the term “daylight saving.” However, by 1911, the term “summer time” had replaced “daylight saving time” in draft legislation. [108] Similar expressions are employed in numerous 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. [78]

The designation of local time typically changes when DST is observed. In American English, “standard” is replaced by “daylight,” for instance, 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). British English commonly inserts “summer” into other time zone names, such as Central European Time (CET) becoming Central European Summer Time (CEST).

In North American English, the mnemonic phrase “spring forward, fall back” (along with variations like “spring ahead,” “spring up,” and “… fall behind”) is widely used to remember the direction of the clock shift. [169] [67]

Computing

A 2001 US public service advertisement served as a reminder to adjust clocks.

Modifications to DST rules have historically presented challenges for existing computer systems. For example, the 2007 change to DST rules in North America necessitated significant upgrades to numerous computer systems, particularly impacting e-mail and calendar programs. These required upgrades represented a considerable undertaking for corporate information technology departments. [170]

To circumvent issues related to clock shifts and time zone variations, some applications standardize on UTC (Coordinated Universal Time). Similarly, most modern operating systems internally manage and store all times in UTC, converting them to local time only for display purposes. [172] [173] However, even when UTC is used internally, these systems still require external updates, such as leap second adjustments, and accurate time zone information to correctly calculate and display local time when needed. Many systems currently in use derive their date and time calculations from data sourced from the tz database , also known as zoneinfo.

IANA Time Zone Database

The Internet Assigned Numbers Authority (IANA) maintains the tz database , which maps named locations to their historical and predicted clock shift patterns. This database is utilized by a wide array of computer software systems, including most Unix-like operating systems, Java , and the Oracle RDBMS . [174] Hewlett-Packard’s “tztab” database serves a similar purpose but is incompatible. [175] When temporal authorities implement changes to DST rules, updates to zoneinfo are typically installed as part of routine system maintenance. In Unix-like systems, the TZ environment variable specifies the desired location name , for example, TZ=’:America/New_York’. Many of these systems also have a system-wide setting that is applied if the TZ environment variable is not explicitly set. This system-wide setting is determined by the content of the /etc/localtime file, which is usually a symbolic link or hard link pointing to one of the zoneinfo files. Internal time is stored in a time-zone-independent format known as Unix time ; the TZ setting is then used by each of the potentially numerous simultaneous users and processes to independently localize time displays.

Older or less sophisticated systems may support only the TZ values mandated by POSIX , which typically specify at most one start and one end rule directly within the value. For instance, TZ=‘EST5EDT,M3.2.0/02:00,M11.1.0/02:00’ defines the time for the eastern United States starting from 2007. Such a TZ value requires manual updating whenever DST rules change, and the new value applies retroactively to all years, potentially mishandling older timestamps. [176]

Opposition to Clock Changes

• 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 the practice of changing clocks twice a year generally falls into three main categories:

• A preference for year-round standard time.

• A preference for year-round daylight saving time.

• A desire to “lock the clock” to a fixed time, regardless of whether that time is permanent standard or permanent daylight time. [177] [178]

The William Willett Memorial Sundial in Petts Wood , South London, is perpetually set to DST.

A shift to permanent daylight saving time (maintaining summer hours year-round without clock changes) is occasionally advocated and is currently in effect in several jurisdictions, including Argentina, Belarus, [179] Iceland, Kyrgyzstan, Morocco, [54] Namibia, Northern Cyprus , Paraguay , Saskatchewan , Syria, Turkey, Turkmenistan, Uzbekistan, and the Yukon . While Saskatchewan officially observes Central Standard Time, its capital city, Regina , experiences solar noon close to 13:00, effectively placing it on permanent daylight time. Similarly, Yukon is categorized within the Mountain Time Zone, but in practice, it observes permanent Pacific Daylight Time to align with the Pacific time zone during summer. However, local solar noon in the capital, Whitehorse , occurs nearer to 14:00, meaning Whitehorse is effectively on “double daylight time.” [ citation needed ]

The United Kingdom and Ireland implemented an extra hour advance during World War II and experimented with year-round summer time between 1968 and 1971. [180] Russia transitioned to permanent DST from 2011 to 2014, but this move proved unpopular due to the extremely late winter sunrises. In 2014, Russia permanently reverted to standard time. [181] Conversely, the shift to permanent DST has been well-received in Turkey, with the Minister of Energy and Natural Resources citing significant energy cost savings and reductions in depression and anxiety levels attributed to increased exposure to daylight. [182]

In September 2018, the European Commission proposed ending seasonal clock changes starting in 2019. [183] Member states would then have the option to permanently adopt either daylight saving time or standard time. In March 2019, the European Parliament approved the commission’s proposal, though it deferred implementation from 2019 to 2021. [184] In response to this proposal, the European Sleep Research Society issued a statement asserting that “installing permanent Central European Time (CET, standard time or ‘wintertime’) is the best option for public health.” [185] As of October 2020, the decision remains unconfirmed [ Needs update ] by the Council of the European Union. [186] The council has requested the commission to provide a detailed assessment of the proposal’s effects, but the Commission maintains that it is the responsibility of the Member States to reach a common position within the Council. [187] This stalemate has effectively halted progress on the issue. [188]

In the United States, several states have passed legislation to implement permanent DST, but these bills necessitate Congressional action to amend federal law before they can take effect. The Uniform Time Act of 1966 permits states to opt out of DST and observe permanent standard time, but it does not allow for permanent DST. [100] [189] Florida Senator Marco Rubio has been a prominent advocate for amending federal law to establish permanent DST, [190] receiving support from the Florida Chamber of Commerce, which anticipates increased evening revenue from extended daylight during peak tourist seasons. [191] In 2022, Rubio’s “Sunshine Protection Act” passed the United States Senate via voice consent without prior committee review, a move that left many senators surprised, with some later claiming unawareness of the vote or its subject matter. [192] The bill subsequently stalled in the US House of Representatives, where questions arose regarding whether permanent DST or permanent standard time would ultimately be more beneficial. [102] [193] Public opinion polls conducted as of 2025 indicate a growing majority of Americans now favor permanently ending DST, with 54% reporting a preference for a permanent switch to standard time. This emerging majority suggests that permanent DST would still be favored over maintaining the current system of twice-yearly clock changes, which is the least popular option overall. [194] [195]

Advocates for permanent DST cite the same advantages as regular DST but without the disruption caused by the biannual clock shifts. Additional purported benefits include safer roadways, a boost to the tourism industry, and energy savings. Detractors, however, point to the relatively late sunrises that permanent DST would entail, particularly during the winter months. [196]

A number of experts in the fields of circadian rhythms and sleep health recommend year-round standard time as the most beneficial option for public health and safety. [140] [141] [142] [143] Conversely, some experts maintain that permanent daylight saving time is still a preferable alternative compared to the current system of annual clock changes. [197] [198] Several chronobiology societies have issued position papers opposing the permanent adoption of DST. A statement from the Society for Research on Biological Rhythms argues: “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.” The World Federation of Societies for Chronobiology has recommended “reassigning countries and regions to their actual sun-clock based time zones” and holds the position of being “against the switching between DST and Standard Time and even more so against adopting DST permanently.” [200] The American Academy of Sleep Medicine (AASM) advocates that “seasonal time changes should be abolished in favor of a fixed, national, year-round standard time,” [201] and asserts that “standard time is a better option than daylight saving time for our health, mood and well-being.” [202] This position has garnered endorsements from over 20 other organizations, including the American College of Chest Physicians , the National Safety Council , and the National PTA . [203]

Surveys conducted between 2021 and 2022 by the National Sleep Foundation, YouGov , CBS , and Monmouth University indicate a preference among more Americans for permanent DST. [204] [205] [206] Conversely, a 2019 survey by the National Opinion Research Center and a 2021 survey by the Associated Press suggest that more Americans favor permanent Standard Time. [207] [208] Polls from the National Sleep Foundation, YouGov, and Monmouth University have shown a significant leaning towards making daylight saving time permanent. The Monmouth University poll reported 44% favoring year-round DST and 13% preferring year-round standard time. [205] The NORC at the University of Chicago found that 79% of respondents favored permanent DST during the Oil Crisis in December 1973; by February of the following year, 42% supported it. [209]

As of 2025, polls indicate a slight majority of surveyed Americans favor abolishing DST, [194] with momentum building across various regions towards either abolishing DST and permanently adopting standard time [210] or making DST permanent. Common arguments cited for abolishing or making DST permanent include concerns about health risks, economic costs, sleep disruption, and interference with daily routines. [211]

See also

• 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

• ^ Beginning after Passover and concluding before Yom Kippur (resulting in a period of less than 180 days).

• ^ Although DST does not alter the total duration of the fast, which remains 25 hours regardless, many find it easier to commence and conclude the observance earlier rather than later.

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• ^ • 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.

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• ^

• 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.

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• ^ • 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.

• ^ • 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. S2CID 210956409.

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• ^ 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.

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• • “Daylight saving hits late risers hardest”. ABC News. Australia. 25 October 2007. Archived from the original on 3 December 2019. Retrieved 13 February 2009.

• ^ • Weed, Lara; Zeitzer, Jamie M. (23 September 2025). “Circadian-informed modeling predicts regional variation in obesity and stroke outcomes under different permanent US time policies”. Proceedings of the National Academy of Sciences. 122 (38) e2508293122. doi :10.1073/pnas.2508293122. PMC 12478180. PMID 40953265.

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• ^ • Rakoff, Todd D. (2002). A Time for Every Purpose: Law and the Balance of Life. Harvard University Press. p. 26. ISBN 978-0-674-00910-3.

• ^ • 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.

• ^ • 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.

• ^ • Knight, Dana (17 April 2006). “Daylight-saving time becomes daylight-spending time for many businesses”. Indianapolis Star.

• ^ • Bradley, Barbara (3 April 1987). “For business, Daylight Saving Time is daylight spending time”. The Christian Science Monitor.

• ^ • 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.

• ^ • 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.

• ^ • Crandall, Joey (24 October 2003). “Daylight saving time ends Sunday”. Record–Courier. Archived from the original on 29 February 2012.

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• ^ • “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 …’

• ^ • “Should we change the clocks?”. National Farmers Union. Archived from the original on 14 March 2012. Retrieved 6 January 2012.

• ^ • 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.

• ^ 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

• ^ • Ruderman, Jesse (1 November 2006). “Continuous daylight saving time”. Archived from the original on 4 May 2016. Retrieved 21 March 2007.

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• ^ • Holloway, Leith (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.

• ^ Seize the Daylight (2005), p. xv.

• ^ Daylight saving time and its variants:

• • Meade, Richard A. (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. Retrieved 25 October 2025. 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

• ^ • Garner, Bryan A. (2000). “daylight saving(s) time”. Oxford Dictionary of American Usage and Style. Oxford University Press. p. 95. ISBN 978-0-19-513508-4. Archived from the original on 9 November 2021. Retrieved 6 June 2020.

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• ^ • Lohr, Steve (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.

• ^ • 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.

• ^ • Bean, Ron (November 2000). “The Clock Mini-HOWTO”. Archived from the original on 13 January 2012. Retrieved 10 January 2012.

• ^ • Chen, Raymond (November 2000). “Why does Windows keep your BIOS clock on local time?”. Archived from the original on 3 January 2012. Retrieved 10 January 2012.

• ^ • Paul Eggert; Arthur David Olson. “Time zone and daylight saving time data”.

• ^ • “tztab(4)” (PDF). HP-UX Reference: HP-UX 11i Version 3. Hewlett–Packard Co. 2010. Archived from the original (PDF) on 21 September 2013.

• ^ • “Other environment variables”. IEEE Std 1003.1–2004. The Open Group. 2004. Archived from the original on 6 July 2010. Retrieved 17 February 2007.

• ^ • 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. PMID 36884231. Archived from the original on 18 March 2025. Retrieved 17 March 2025.

• ^ • Phillips, Rasheedah (28 January 2025). Dismantling the Master’s Clock: On Race, Space, and Time. AK Press . ISBN 978-1-84935-562-9.

• ^ • 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.

• ^ • 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.

• ^ • “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.

• ^ • “Turkey will not turn back the clock for daylight saving time”. Daily Sabah. 7 December 2021. Retrieved 20 September 2022.

• ^ • “Press corner”. European Commission. 12 September 2018. Archived from the original on 23 October 2020. Retrieved 23 October 2020.

• ^ • “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.

• ^ • “To the EU Commission on DST” (PDF). March 2019. Archived (PDF) from the original on 30 December 2020. Retrieved 4 November 2021.

• ^ • “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.

• ^ • 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.

• ^ • 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.

• ^ • “Fall back! Daylight saving time ends Sunday”. USA Today. 1 November 2018. Archived from the original on 2 November 2018. Retrieved 2 November 2018.

• ^ • “Rubio’s Bill to Make Daylight Saving Time Permanent Passes Senate”. rubio.senate.gov. 15 March 2022. Archived from the original on 28 June 2022. Retrieved 15 June 2022.

• ^ • Haughey, John (18 September 2022). “Time – and money – at stake in Florida-led proposal to extend daylight saving”. The Center Square Florida. Archived from the original on 3 January 2023. 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.

• ^ • McLeod, Paul (17 March 2022). “Everyone Was Surprised By The Senate Passing Permanent Daylight Saving Time. Especially The Senators”. BuzzFeed. Archived from the original on 3 January 2023. Retrieved 3 January 2023.

• ^ • Schnell, Mychael (25 July 2022). “Permanent daylight saving time hits brick wall in House”. The Hill. Archived from the original on 5 April 2024. Retrieved 3 January 2023.

• ^ 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.

• ^ • Tuccille, J. D. (10 March 2025). “We’re overdue to end Daylight Saving Time”. Reason.com. Archived from the original on 14 March 2025. Retrieved 11 March 2025.

• ^ • 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.

• ^ • Team, The Health News (4 November 2022). “Is Daylight Saving Time Good or Bad? | Sharp HealthCare”. www.sharp.com . Archived from the original on 4 December 2024. Retrieved 4 December 2024.

• ^ • Kernan, Megan (18 March 2022). “Sleep experts weigh in on Senate approving bill to make Daylight Saving Time permanent”. Retrieved 19 September 2022.

• ^ • 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.

• ^ • 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.

• ^ • 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.

• ^ • “American Academy of Sleep Medicine opposes permanent daylight saving time bill”. 23 May 2022. Retrieved 3 January 2023.

• ^ • “American Academy of Sleep Medicine calls for elimination of daylight saving time”. 27 August 2020. Archived from the original on 3 January 2023. Retrieved 3 January 2023.

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• ^ a b • “States Object to Changing the Clocks for Daylight Saving Time”. Almanac.com. 6 January 2023. Archived from the original on 7 January 2023. Retrieved 7 January 2023.

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Sources

• • Downing, Michael (2005). Spring Forward: The Annual Madness of Daylight Saving Time. Shoemaker & Hoard. ISBN 978-1-59376-053-3.

• • Prerau, David (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

• • Bartky, Ian R. (2007). One Time Fits All: The Campaigns for Global Uniformity. Stanford University Press. ISBN 978-0-8047-5642-6.

External links

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