Daylight saving time (DST) means moving the clocks forward one hour in spring and back one hour in autumn, so that more daylight falls in the evening instead of the early morning. In the United States the clocks “spring forward” in March and “fall back” in November.2 In the European Union they change on the last Sunday of March and the last Sunday of October.9
The idea took hold in wartime. Germany and Austria began moving their clocks on April 30, 1916, to save electricity for the war effort, and the United States followed in 1918. Congress set national rules for it in the Uniform Time Act of 1966.2
Today only about a third of the world's countries use daylight saving time, and most of them are in Europe. About half of all countries used it in the past but have stopped, including Russia, Turkey and Iran.1 Mexico scrapped it in 2022 after a Senate vote of 59 to 25, though some towns on the US border kept it.11 In the US, Hawaii and most of Arizona never change their clocks.5
Many people are tired of the switch. In a Gallup poll from January 2025, 54% of Americans said they were ready to do away with daylight saving time. In 1999, 73% had favored it.3 When the European Commission asked the public in 2018, about 4.6 million people replied and 84% wanted the twice-yearly changes to end. The European Parliament voted in March 2019 to stop them by 2021, but EU governments have still not agreed, so the clocks keep changing.9
The real fight is over which clock to keep. Sleep scientists want permanent standard time. The American Academy of Sleep Medicine, backed by 20 other organizations, says: “Permanent standard time is the optimal choice for health and safety.”4 Lawmakers have mostly pushed the other way. Nineteen US states have passed laws or resolutions for year-round daylight saving time, but federal law does not allow it, so they must wait for Congress.6
Congress keeps coming close. On March 15, 2022, the Senate passed the Sunshine Protection Act, which would make daylight saving time permanent, without a single objection, but the House never voted on it.6 In July 2026 the House passed a new version by 308 votes to 117.7 President Trump has called daylight saving time “inconvenient, and very costly to our nation,”27 but has also described the choice as “a 50-50 issue.”28 In October 2026, Senate Majority Leader John Thune said the bill had “no clear path forward.”8
Neighbors are picking different answers. British Columbia in Canada changed its clocks for the last time on March 8, 2026, and now stays on daylight saving time all year.14 In this guide, the Pro side wants to abolish daylight saving time and keep standard time all year. The Con side wants to keep daylight saving time, either with the current switch or locked in permanently.
Key terms
Standard time
The normal clock time for a time zone, used in winter where clocks change. Arizona and Hawaii use it all year.
Daylight saving time
Setting clocks one hour ahead in spring and back in autumn, so that more daylight falls in the evening.
Permanent daylight saving time
Keeping summer clock time all year, so winter sunrises and sunsets both come an hour later. Supporters call it “locking the clock.”
Circadian rhythm
The body's internal daily clock, which controls when we feel sleepy or alert. Light, especially morning light, keeps it on time.
Time zone
A region that shares the same clock time. On the western edge of a zone, the sun rises and sets later by the clock than on the eastern edge.
Natural experiment
A real-world event, like a clock change, that splits people into groups so researchers can compare them almost as if in a planned test.
Sunshine Protection Act
The US bill that would make daylight saving time permanent nationwide. It passed the Senate in 2022 and the House in 2026, but has not become law.
Pros and cons at a glance
Pro: abolish it
Con: keep it
Pro arguments
Con arguments
Key clashes
Most daylight saving time debates are won or lost on these four questions.
1Morning light or evening light: which matters more?
Both sides want the same hours of sun, at different ends of the day.
Pro saysMorning light keeps the body clock on time, and dark mornings are harder on health than dark evenings.413
Con saysEvening light cuts robberies and gives children more time to play outside after school.2324
2Is the switch the problem, or daylight saving time itself?
Ending the switch is popular. The fight is over what replaces it.
Pro saysEven without any switch, later sunsets are linked to shorter sleep and worse health, as time zone research shows.21
Con saysThe heart attack and crash spikes come from the spring jump, which permanent daylight saving time also ends. One heart study found the total for the whole week did not change.1517
3Do 1974 and Russia prove that permanent summer time fails?
History is evidence, but each place and era is different.
Pro saysTwice, people turned against summer time in winter, within months in the US and within three years in Russia.1013
Con saysThose were different times and places. British Columbia chose permanent daylight saving time after 93% backed it in a public survey.14
4Who should decide: doctors or voters?
Medical experts and elected lawmakers have mostly reached opposite answers.
Pro saysSleep doctors back standard time, and the largest group of Americans, 48%, would keep it all year.34
Con saysNineteen states and a large House majority have voted for permanent daylight saving time.67
Around the world
The US: Hawaii and most of Arizona stay on standard time all year. Nineteen states want permanent daylight saving time if Congress allows it.56 The House passed a bill to allow it in July 2026, but its future in the Senate is unclear.78
Europe: Most European countries use daylight saving time.1 The European Parliament voted in 2019 to end the clock changes, but EU governments have not agreed on a plan.9
Mexico and Canada: Mexico abolished daylight saving time in 2022, except in some border areas.12 British Columbia went the other way and made it permanent in 2026.14
Russia: Russia moved to permanent summer time in 2011, then to permanent winter time in 2014.13
The global picture: Only about a third of countries use daylight saving time. Egypt is the only African country that does.1
Debate tip: comparing countries is useful evidence on both sides. Pro can point to the many countries that have dropped daylight saving time; Con can point to British Columbia, which chose permanent daylight saving time after a huge public survey.
Discussion questions
For class or club discussion. There are no right answers; ask for reasons and evidence.
Should daylight saving time be abolished? Explain your answer using at least one argument from each side.
If you had to choose one for the whole year, would you pick lighter mornings or lighter evenings? Who gains and who loses from your choice?
Should health experts or voters have the final say on what time the clocks show? Why?
The US tried year-round daylight saving time in 1974 and gave it up within a year. Is that history a good guide to what would happen today?
Should neighboring states or countries be required to use the same clock time, even if their people want different things?
Sources
Laura Silver, Laura Clancy and Jenn Hatfield, “Most countries don't observe daylight saving time,” Pew Research Center, October 26, 2023. LinkResearch nonprofit
Evan Andrews, “Why Do We Have Daylight Saving Time?” History.com, first published March 6, 2014. LinkHistory reference
Gallup, “More Than Half in U.S. Want Daylight Saving Time Sunsetted,” March 4, 2025. LinkPoll
American Academy of Sleep Medicine, “New position statement supports permanent standard time,” October 31, 2023. LinkMedical society
“Senate votes to make daylight saving time permanent,” CNBC, March 15, 2022. LinkNews report
Jim Reed, “Clock Changing Persists for at Least Another Year,” National Conference of State Legislatures, October 31, 2022. LinkLegislative research body
Amelia Twyman, “US House passes bipartisan bill to make daylight saving time permanent,” States Newsroom, in Florida Phoenix, July 15, 2026. LinkNews report
“John Thune: No Clear Path Forward On Daylight Saving Bill,” iHeartRadio, citing Politico, October 6, 2026. LinkNews report
European Commission, Directorate-General for Mobility and Transport, “Summertime.” LinkGovernment policy
Andrew Beaujon, “The US Tried Permanent Daylight Saving Time in the '70s. People Hated It,” Washingtonian, March 15, 2022. LinkMagazine report
Associated Press, “Mexico scraps daylight savings time except along US border,” KTVU, October 26, 2022. LinkNews report
timeanddate.com, “Mexico Abolishes DST,” October 2022. LinkTime reference service
“Russia turns back the clocks,” SBS News, October 26, 2014. LinkNews report
Government of British Columbia, news release on adopting permanent daylight saving time, March 2, 2026. LinkGovernment statement
American College of Cardiology, “Daylight Saving Impacts the Timing of Heart Attacks,” on research by Amneet Sandhu, March 29, 2014. LinkMedical society, research summary
American Psychological Association, “Changing to Daylight Saving Time Cuts Into Sleep and Increases Workplace Injuries,” on Barnes and Wagner, Journal of Applied Psychology, September 1, 2009. LinkPeer-reviewed study, summary
“New Study: Daylight Saving Time Linked to 28 Fatal Car Accidents Per Year,” Sleep Review, February 5, 2020, on Fritz and others, Current Biology. LinkPeer-reviewed study, summary
Amber N. Woods, Rebecca A. Weast and Samuel S. Monfort, “Daylight saving time and fatal crashes: the impact of changing light conditions,” Journal of Safety Research, February 2025, via the Insurance Institute for Highway Safety. LinkPeer-reviewed study
Matthew J. Kotchen and Laura E. Grant, “Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana,” NBER Working Paper 14429, October 2008. LinkEconomic research
US Department of Energy, “Impact of Extended Daylight Saving Time on National Energy Consumption: Report to Congress,” October 2008. LinkGovernment report
“The hazards of living on the right side of a time zone border,” The Conversation, on Giuntella and Mazzonna, Journal of Health Economics, 2019. LinkPeer-reviewed study, summary
Frank Batten School of Leadership and Public Policy, University of Virginia, “Under Cover of Darkness: How Ambient Light Influences Criminal Activity,” Review of Economics and Statistics, December 1, 2015. LinkPeer-reviewed study
“Making daylight saving time permanent could reduce crime, researchers say,” ABA Journal, October 30, 2015. LinkNews report
University of Bristol, “Time for change: additional daylight saving could improve public health,” on Goodman and others, International Journal of Behavioral Nutrition and Physical Activity, October 24, 2014. LinkPeer-reviewed study, summary
JPMorgan Chase Institute, “Shedding Light on Daylight Saving Time,” November 1, 2016. LinkEconomic research
Laura Bratton, slideshow on the businesses that benefit from daylight saving time, Quartz, updated March 9, 2024. LinkNews report
“Trump says it's ‘hard to get excited’ about changing daylight saving time,” Axios, March 6, 2025. LinkNews report
“Trump not sold on push to change daylight saving time: ‘50-50 issue’,” Colorado Politics, March 6, 2025. LinkNews report
“Senate passes bill to make daylight saving time permanent,” Boston Globe, March 15, 2022. LinkNews report
Arguments marked “Evidence needed” are waiting for a source before this guide goes live.
