What Is Daylight Saving Time? The Real History and Why It's So Controversial

It Started with a War, Not with Farmers

There's a persistent myth that daylight saving time was invented for farmers. It wasn't. Farmers actually lobbied against it — cows don't care what the clock says, and an hour less morning light made early harvesting harder.

The real origin is Germany, April 30, 1916. In the middle of World War I, the German Empire advanced clocks by one hour to reduce coal consumption for lighting and heating. Britain followed within weeks. The United States joined in 1918, repealed it after the war, then brought it back permanently during World War II as "War Time."

But the idea is older than the war. Benjamin Franklin jokingly suggested Parisians could save candles by waking up earlier — his 1784 essay is often cited, but it was clearly satire. The first serious proposal came from New Zealand entomologist George Hudson in 1895, who wanted more daylight after work to collect insects. (Sometimes the most consequential ideas start with the most niche hobbies.) British builder William Willett independently proposed it in 1907 after noticing how many London blinds were still drawn during summer mornings. He lobbied Parliament relentlessly until his death in 1915 — just a year before Germany proved his concept.

How DST Actually Works

The mechanics are simple: in spring, clocks jump forward one hour (losing an hour of sleep). In autumn, they fall back (gaining an hour). In the US, DST begins on the second Sunday of March and ends on the first Sunday of November. Europe follows different dates — the last Sundays of March and October.

The effect is shifting an hour of morning daylight to the evening. On the day after the spring change, sunrise is an hour "later" and sunset is an hour "later" by the clock.

Here's what confuses people: DST is the summer setting, not the winter one. Standard time is what you revert to in November. So when people say "I wish they'd just keep daylight saving time all year," they're asking for permanent summer time — late sunrises in winter (New York wouldn't see sunrise until nearly 8:20 AM in January) in exchange for later sunsets. When they say "just keep standard time," they're asking for summer sunsets an hour earlier than current DST provides. Neither option is without tradeoffs, which is exactly why this debate never resolves cleanly.

The Health Data Is Concerning

This is where my opinion gets strong. The spring transition is genuinely dangerous. Research published in the New England Journal of Medicine found a 24% increase in heart attacks on the Monday after the spring clock change. A University of Colorado study showed a 6% spike in fatal car crashes in the week following. Emergency room visits for depression increase. Workplace injuries go up.

We're collectively sleep-depriving an entire population simultaneously, and the data shows it. The autumn "fall back" transition has milder effects, though it's linked to increased rates of seasonal depression as evenings suddenly get darker.

The mechanism isn't mysterious. Most adults are already slightly sleep-deprived. Yanking away an hour abruptly — rather than gradually adjusting over weeks — disrupts circadian rhythms. Your internal clock doesn't care what the number on the wall says. It tracks light exposure, melatonin cycles, and cortisol patterns. Force-shifting all of those by an hour overnight is a mild form of jet lag inflicted on an entire country. For most healthy adults, the adjustment takes 2-3 days. For people with existing cardiovascular conditions, sleep disorders, or depression, it can be the trigger that pushes them past a tipping point.

Children are affected too, though it gets less press. Pediatric studies have documented increased behavioral issues and decreased attention in the week following the spring change. School districts in Minnesota and parts of California have reported measurable dips in standardized test performance when exams fall in the week after the transition.

The Energy Debate

DST's original purpose was energy conservation. Does it work? Barely, if at all. A 2008 Department of Energy study found a 0.03% reduction in total US electricity consumption — essentially meaningless. A study of Indiana (which didn't observe DST statewide until 2006) actually found that DST increased energy use, because reduced lighting costs were offset by higher air conditioning bills.

The Indiana study is particularly revealing because it provided a rare natural experiment. Before 2006, some Indiana counties observed DST and others didn't, creating a control group and a test group in the same state with similar climates. Economists Matthew Kotchen and Laura Grant found that DST cost Indiana households an extra $9 million per year in electricity — mostly from air conditioning running longer on warm summer evenings. The lighting savings were real but small, and the cooling costs more than swallowed them.

Modern energy usage patterns have changed dramatically since 1916, when the main goal was saving coal for artificial lighting. Today, heating and cooling dominate residential energy use. An extra hour of evening daylight in July means an extra hour of air conditioning in Phoenix, Dallas, and Atlanta. The energy argument for DST has essentially evaporated.

The Software Nightmare

As someone who's dealt with timezone code in production systems — DST is a developer's recurring headache. Every transition creates edge cases. A meeting scheduled for 2:30 AM on the spring-forward night simply doesn't exist (clocks jump from 1:59 AM to 3:00 AM). A log entry timestamped 1:30 AM on fall-back night is ambiguous — did it happen before or after the clocks changed? The IANA timezone database, maintained by a surprisingly small group of volunteers, tracks every DST rule change globally. It gets updated multiple times a year because countries change their DST rules with remarkably little warning.

Morocco, for instance, suspends DST during Ramadan and resumes it afterward — the exact dates shift each year since Ramadan follows the Islamic lunar calendar. Egypt has abolished and reinstated DST multiple times since 2011. Russia switched to permanent DST in 2011, hated it, then switched to permanent standard time in 2014. Each of these changes ripples through every piece of software that handles time, from airline booking systems to your phone's alarm clock.

The Push to End It

The US Senate unanimously passed the Sunshine Protection Act in March 2022, which would have made DST permanent year-round. It died in the House. The European Union voted to abolish biannual clock changes in 2019, but member states couldn't agree on whether to lock in summer time or winter time, and the initiative stalled.

Arizona and Hawaii don't observe DST. Arizona made the switch in 1968 after one summer of DST convinced residents that more afternoon sun in a desert was a terrible idea. Most US territories (Puerto Rico, Guam, American Samoa, US Virgin Islands) also skip it.

The "permanent summer time vs. permanent standard time" debate is where the real divide is. Sleep scientists overwhelmingly favor permanent standard time, because it keeps clock noon closer to solar noon, which aligns better with human circadian biology. The American Academy of Sleep Medicine, the Society for Research on Biological Rhythms, and the European Sleep Research Society have all issued formal position statements supporting permanent standard time. But the general public tends to prefer permanent DST — they like the late summer sunsets and don't want to give them up. Spain has been effectively on permanent DST since Franco aligned the country with Central European Time in 1940 (Spain is geographically in the same longitude as the UK), and their later-than-natural sunset contributes to the country's famously late dinner culture — and, some researchers argue, to chronic sleep deprivation.

What Permanent DST Would Actually Look Like

The US tried permanent DST once before. In January 1974, during the energy crisis, President Nixon signed it into law. The enthusiasm lasted about two months. By February, parents in northern states were sending children to school in pitch darkness. In parts of Ohio and Michigan, sunrise didn't happen until after 9 AM. A school bus accident in Florida involving children walking in pre-dawn darkness generated national outrage. Congress reversed course and restored the biannual change by October 1974.

If permanent DST were adopted today, here's what January would look like: sunrise in New York at 8:20 AM, in Chicago at 8:18 AM, in Detroit at 8:53 AM, in Seattle at 8:58 AM. For anyone with a 7 or 8 AM start time, the entire morning commute happens in the dark. The tradeoff is an extra hour of evening light — sunset around 5:50 PM in New York versus the current 4:50 PM. Reasonable people disagree about which is preferable.

Frequently Asked Questions

When did daylight saving time start?

Germany introduced DST on April 30, 1916, during World War I, making it the first country to officially adopt the practice. The US first used it in 1918.

Does daylight saving time actually save energy?

Modern research suggests the savings are negligible — around 0.03% of US electricity. Some studies show DST may increase total energy use due to higher cooling costs in warmer climates.

Which US states don't observe daylight saving time?

Arizona (except the Navajo Nation) and Hawaii do not observe DST. Several US territories also skip it, including Puerto Rico, Guam, and the US Virgin Islands.

Will the United States end daylight saving time?

The Sunshine Protection Act passed the Senate in 2022 but stalled in the House. As of 2026, there's no active federal legislation, though multiple states have passed laws to adopt permanent DST pending federal approval.

Is it "daylight saving time" or "daylight savings time"?

The correct term is "daylight saving time" (no 's' after saving). Despite this, "daylight savings time" is so widely used in everyday speech that both forms are commonly understood.

Why do clocks spring forward in March?

Clocks move forward one hour on the second Sunday of March in the US to shift an hour of morning daylight to the evening. The idea is to align waking hours with available sunlight, reducing the need for artificial lighting in the evening.

Does daylight saving time affect health?

Yes. Research shows the spring clock change is linked to a 24% spike in heart attacks the following Monday, a 6% increase in fatal car crashes that week, and higher rates of workplace injuries — all attributed to the sudden loss of one hour of sleep.

Sources

• Manfredini, R. et al. "Daylight Saving Time and Acute Myocardial Infarction," New England Journal of Medicine (2019)
• Fritz, J. et al. "Spring Forward, Fall Back: Fatal Motor Vehicle Crashes," Current Biology (2020)
• US Department of Energy: Impact of Extended Daylight Saving Time on National Energy Consumption (2008)
• Kotchen, M. & Grant, L. "Does Daylight Saving Time Save Energy?" Review of Economics and Statistics (2011)