Why do we change the clocks?
Losing an hour, or losing the light?
Every spring, the clocks jump. Which loss do you mind more? ⏰
There are two ways to lose. 🤔
Losing an hour
One night in March. The clock skips ahead. You sleep less.
Losing the light
Keep summer time all year, and winter mornings stay dark.
From NIST and Barnes & Wagner and Roenneberg et al. and TIME
Sunday, 8 March 2026. Mia's alarm rings at seven.
Her body says it is six. 😴 Outside, it is still dark.
From NIST
1:59
3:00
In the US, at 2:00 a.m. that night…
…the clock jumped to 3:00.
That hour never happened. In autumn, the clocks go back.
Spring forward: move the clock from 1:59 to 3:00
The clock jumped from 1:59 to 3:00. One hour was skipped.
A clock showing 1:59
A clock showing 3:00
From NIST
daylight saving time
[day·lite say·ving time]
noun
moving clocks one hour ahead in the warm months.
it moves light from early morning to the evening.
in Britain, it is called “summer time”.
From NIST and British Summer Time
The sun doesn't move. Only the numbers do.
Same sunlight. We just give it a later name.
A drawing, not real sunrise times.
standard
summer time
Daylight band. Under it, an hour ruler. After the change, the ruler moves one hour; the light stays.
From NIST and Roenneberg et al.
Did Ben Franklin invent it?
No.
In 1784 he wrote a joke letter. It was satire.
Text: Benjamin Franklin, An Economical Project, 1784
Let cannon be fired in every street, to wake the sluggards effectually
Benjamin Franklin, 1784
Fire cannons to get lazy Parisians out of bed. 🤭 He was teasing.
1895
A bug collector in New Zealand wants lighter evenings. 🐛
George Vernon Hudson suggested moving the clocks. Accounts say he wanted time to hunt insects.
From The Franklin Institute and History.com
William Willett, 1909
Two men in suits and hats outside the Houses of Parliament, 1909.
William Willett, a London builder. 🏗️ In 1907 he wrote The Waste of Daylight.
Credit: Sir Benjamin Stone, 1909 · National Portrait Gallery, London
From British Summer Time and Prerau
Willett's plan: four jumps of 20 minutes, every April.
A bill failed in 1909. He died in 1915, before Britain said yes.
From British Summer Time and Prerau
30 April 1916
Germany goes first. It wants to save coal for the war.
21 May 1916
Britain follows three weeks later.
From History.com and British Summer Time and timeanddate
1918 US daylight saving poster
A 1918 poster. Uncle Sam turns a clock hand forward and a crowd cheers.
1918. America gets time zones, and summer time. 🇺🇸
In 1919, Congress dropped summer time. It overruled the president's veto.
Credit: United Cigar Stores Co., 1918 · Library of Congress
1974. America tries summer time all winter. ❄️
January 1974
February 1974
liked it
about
Kids walked to school in the dark. 🎒 By October, it was over.
Poll numbers vary by source.
Support for year-round summer time: about 79% in January 1974
Support for year-round summer time fell to about 42% by February 1974
From Audacy / KRLD
Mia's mum opens the power bill. 💡
“Doesn't the clock change save us money?” she asks.
Does it save energy? Barely.
Indiana
Homes used about 1% more power. Heating and cooling went up.
US report, 2008
Longer summer time saved about 0.03% of a year's power.
44 studies
A big review found 0.34% saved. In hot places, use went up.
From Kotchen & Grant and US Department of Energy and Havranek et al.
Spring hurts. Autumn, not so much.
Losing an hour is harder on the body than gaining one.
From Fritz et al. and Manfredini et al. and Barnes & Wagner
6%
more deadly car crashes
In the US, in the week after the spring change. 🚗 That is about 28 extra deaths a year.
From Fritz et al. and CU Boulder Today
These effects on fatal traffic accidents are real, and these deaths can be prevented.
Céline Vetter, sleep scientist, CU Boulder
The extra crashes are not bad luck. We could stop them.
From CU Boulder Today
Your body notices too.
Heart attacks
About 5% more risk for two weeks.
Sleep
US workers sleep about 40 minutes less that Monday.
Injuries
Miners got hurt more often, and worse.
Autumn
No clear effect when the clocks go back.
From Manfredini et al. and Barnes & Wagner
Japan tried summer time once. 🇯🇵
1948 · a Summer Time Law, under the Allied occupation
The aim: save coal and power after the war
Workers said their days just got longer
1951 poll: 53% said end it, 30% keep it
1951 · the last summer of it (records vary)
From Kodansha Blue Backs and Japan Ministry of the Environment and ITmedia
2018: summer time for the Tokyo Olympics? 🏟️
About 74% of firms said no. The idea was dropped.
From World Economic Forum and BBC News and Reuters survey
1988
Korea moves its clocks for the Seoul Olympics. 🇰🇷
Events fit US prime time TV. It ran in 1987 and 1988.
From Korea JoongAng Daily and The Korea Times and timeanddate
The necktie brigade
Office workers, Seoul, summer 1987 👔
Light evenings let workers join protests after work.
One columnist thinks this helped bring democracy. It is a view, not proven.
From Korea JoongAng Daily
Both said: we'd just work longer. 💼
Japan dropped it in 1951. Korea's plans in 1997 and 2009 failed too.
From Kodansha Blue Backs and Japan Ministry of the Environment and The Korea Times and The Korea Times
SUMMER ALL YEAR
SUMMER ALL YEAR, crossed out
Russia kept summer time all year, from 2011.
It was unpopular. In 2014, Russia chose winter time for good.
From The Moscow Times
2026: the US tries to stop switching.
House
passed, 308–117 · 14 July 2026
Senate
stuck
stuck
President
backs it
there's no clear path forward or consensus on it yet.
John Thune, Senate leader, October 2026
The Senate is not ready to vote. ⏳
So US clocks still go back on 1 November 2026.
Follow the bill
House: passed, 308 to 117, 14 July 2026. Senate: stuck. President: backs it.
The bill is stuck in the Senate.
From US House Clerk and NBC News and TIME and NIST
410–192
European Parliament vote, March 2019
Europe voted to stop switching. 🇪🇺 But EU countries never agreed. It is still stuck.
From European Parliament and Global News and LRT
Standard all year
Sleep scientists pick this. Morning light sets your body clock.
Summer all year
More Americans pick this: 56% to 42%.
From AASM and Roenneberg et al. and TIME
People tell me: just keep summer time all year. ☀️
But…
Picture a January morning. 🌑
From TIME
A January morning, with summer time all year.
Sunrise would come after 9 a.m. 🌑 Mia would walk to school in the dark.
The soft dawn edge is drawn, not measured.
standard time
summer time all year
Indianapolis · 15 January 2027
Morning in Indianapolis on 15 January 2027. With summer time all year, sunrise would come after 9 a.m.
From TIME
1 November 2026. Mia gets her hour back. 🛌
Next March, it will vanish again. Unless someone decides.
From NIST
⏰ Clocks move. The sunlight does not.
❤️ The spring jump is the risky one.
🤷 Most want to stop switching. Nobody agrees which time.
Or maybe “saving” is the wrong word. 🤔
We never saved any daylight. We only moved it. So: losing an hour, or losing the light?
From NIST and Roenneberg et al.
Words from the story
- Daylight saving time
- Moving clocks one hour ahead in the warm months.
- Standard time
- The “normal” clock time, used in winter.
- Satire
- A joke that pretends to be serious.
- Meta-analysis
- A study that adds up many studies to find the overall answer.
- Body clock
- Your body's own daily timer. Morning light resets it.
- Occupation
- When another country's army runs a place for a while.
- Prime time
- The evening hours when most people watch TV.
- Senate
- One half of the US Congress. Both halves must pass a law.
Where this comes from
- Roll Call 238, H.R. 139. Clerk, US House of Representatives, 14 July 2026
- House passes Trump-backed bill that would make daylight saving time permanent. NBC News, 14 July 2026
- Permanent standard time is the optimal choice for health and safety. American Academy of Sleep Medicine, 2024
- A Chronobiological Evaluation of the Acute Effects of Daylight Saving Time on Traffic Accident Risk. Current Biology, 2020
- Spring forward to daylight saving time brings surge in deadly crashes. CU Boulder Today, 30 January 2020
- Daylight Saving Time (DST). NIST
- Did Ben Franklin Invent Daylight Saving Time?. The Franklin Institute
- Daylight Savings Time: Start, Dates & Origins. History.com
- British Summer Time. Wikipedia
- Written Evidence, Dr David Prerau (SCT0008). Written evidence to UK Parliament committees
- DST history, Germany 1916. timeanddate.com
- Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana. NBER / Review of Economics and Statistics, 2011
- Impact of Extended Daylight Saving Time on National Energy Consumption. US Department of Energy, 2008
- Does Daylight Saving Save Electricity? A Meta-Analysis. Energy Journal, 2018
- Daylight Saving Time and Acute Myocardial Infarction: A Meta-Analysis. Journal of Clinical Medicine, 2019
- European Union daylight savings time vote. Global News, 26 March 2019
- Press release 20190321IPR32107. European Parliament, 26 March 2019
- Why hasn't Europe phased out daylight saving time?. LRT, 28 March 2026
- Most Americans Want to Stop Changing the Clocks. Here's Why Senators Are Hesitating. TIME, 7 October 2026
- History of time in the United States. Wikipedia
- US tried permanent daylight saving time in 1974. It didn't last long. Audacy / KRLD, 16 July 2026
- Russia to switch to permanent winter time. The Moscow Times, 1 July 2014
- Save summer time in Seoul. Korea JoongAng Daily (column), 30 June 2009
- Summer time. The Korea Times (column), 16 August 2018
- 4月28日 日本で「夏時刻法」が公布(1948年). Kodansha Blue Backs / gendai.media, 28 April 2020
- 平成21年度サマータイムパンフレット. Ministry of the Environment, Japan, 2009
- 日本にサマータイムは有効か. ITmedia News, April 2005
- Spain's 2026 plan to end clock changes has failed. Euro Weekly News, 5 September 2026
- Parts of Australia move clock forward as daylight saving time begins. Bernama / Business Today, 4 October 2026
- Changing to Daylight Saving Time Cuts Into Sleep and Increases Workplace Injuries. American Psychological Association, 2009
- Why Should We Abolish Daylight Saving Time?. Journal of Biological Rhythms, 2019
- Should Japan introduce daylight savings time?. World Economic Forum, November 2018
- Tokyo 2020 Olympics: Japan debates daylight saving to avoid heat. BBC News, August 2018
- Japan firms oppose DST. News On Japan (Reuters Corporate Survey), 15 September 2018
- DST in S. Korea 1949–1961?. IANA tz mailing list, July 2006
- Time change South Korea 1987 / 1988. timeanddate.com
- S. Korea may resume daylight saving time. The Korea Times, 27 April 2009
Mia is made up. The clock, the light strips and the melting bar are drawings that show the idea. The Indianapolis sunrise is a projection quoted by TIME. Poll numbers from 1974 vary by source. Korea's “necktie brigade” link is one columnist's view. Photos: William Willett by Sir Benjamin Stone, 1909 (National Portrait Gallery, London; public domain, via Wikimedia Commons). Poster: United Cigar Stores Co., 1918 (Library of Congress; public domain).
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