History, Myths & What’s Changing
Twice a year, hundreds of millions of people adjust their clocks by one hour—losing sleep in spring, gaining it back in fall.
Most people do it without much thought. But why do we have daylight saving time at all? Who decided this was a good idea, and does it still make sense today?
The short answer: daylight saving time was created to make better use of natural daylight during the hours most people are awake, and it was formally adopted during World War I as a way to conserve fuel. But the full story is more complicated—and far more interesting—than that.
This post walks through the real origins of daylight saving time, why countries adopted it, what the evidence says about its actual effects, and where the ongoing debate about keeping or abolishing it now stands.
Table of Contents
The Idea Predates the 20th Century
The concept of adjusting clocks to match daylight hours didn’t start with governments or wartime policy. It goes back to the late 1800s.
In 1895, a New Zealand entomologist named George Vernon Hudson proposed a two-hour time shift to the Royal Society of New Zealand. His motivation was surprisingly personal—he wanted more after-work daylight to collect insects. The proposal didn’t go anywhere.
About a decade later, a British builder named William Willett independently came up with a similar idea. He argued that the UK should advance its clocks by 80 minutes across four incremental moves each spring, then reverse the process in autumn. Willett campaigned hard for his concept, which he called “Summer Time,” but the British Parliament rejected it. He died in 1915, never seeing his idea become law.
Before either of them, Benjamin Franklin had floated the idea in a 1784 satirical essay suggesting Parisians could save money on candles by waking up earlier to use natural morning light. Franklin’s piece was more tongue-in-cheek than serious policy proposal, but it planted an early seed.
Why Daylight Saving Time Was Actually Adopted: World War I
The reason we actually have daylight saving time today comes down to wartime energy conservation, not farmers, not recreation, and not Benjamin Franklin’s candle essay.
On April 30, 1916, Germany and Austria became the first countries to officially implement a seasonal one-hour clock shift. The goal was military and industrial: by pushing clocks forward, workers and factories could operate during daylight hours, reducing the demand for artificial lighting and conserving coal and fuel for the war effort.
The United Kingdom followed within weeks. The United States adopted it in 1918, through the Standard Time Act—the same legislation that formally established the country’s official time zones.
Public support evaporated once the war ended. Congress repealed daylight saving time in the US in 1919. It returned during World War II in 1942 under President Franklin D. Roosevelt, then was repealed again in 1945 when the conflict ended.
For roughly two decades after WWII, daylight saving time in the US existed in a patchwork state—some states and cities used it, others didn’t, with no consistency in start and end dates. This created genuine logistical chaos for businesses, broadcasters, and railways.
Congress stepped in with the Uniform Time Act of 1966, which standardized daylight saving time across the country, establishing it from the last Sunday in April to the last Sunday in October. The most recent adjustment came through the Energy Policy Act of 2005, which extended daylight saving time to its current schedule: starting on the second Sunday in March and ending on the first Sunday in November.
No, Farmers Did Not Invent Daylight Saving Time
One of the most persistent myths about why we do daylight saving time is that it was created to help farmers. The opposite is closer to the truth.
Farmers have historically opposed clock changes. Their schedules follow the sun, not the clock—crops don’t care what the clock says, and animals certainly don’t. Shifting clocks disrupts farm schedules, particularly when it means morning milking or harvesting has to be done in conditions that don’t match the new official time.
When daylight saving time was first introduced in the US, farm organizations actively lobbied against it. The 1919 repeal was in large part the result of that agricultural opposition.
The idea that farmers benefit from daylight saving time is a mix-up that stuck—partly because rural life is visually associated with early mornings and sunlight. But the primary beneficiaries of extended evening daylight are retailers, restaurants, entertainment venues, and anyone whose business depends on people being active and outdoors after the workday.
Does Daylight Saving Time Actually Save Energy?
The energy conservation argument is why we have daylight saving time—but decades of research suggest the savings are, at best, very small.
A 2008 Department of Energy study found that daylight saving time reduced overall energy consumption by about 0.02%. That’s not nothing, but it’s close. And the same study found no measurable impact on vehicle fuel consumption.
The issue is that society has changed since WWI. Lighting now accounts for a much smaller share of total energy use. When clocks spring forward and evenings get lighter, people spend more time in their homes and cars—both of which use air conditioning and heating. A 2017 paper published in the International Association for Energy Economics Journal found that rather than saving energy, the extended daylight hours can actually push energy use up in some contexts.
One study found that gaining an extra hour of evening daylight increased electricity demand by roughly 1%. The gains in reduced lighting appear to be offset—or erased—by increased climate control needs.
So why is there still daylight saving time? At this point, the answer is largely habit, legislative inertia, and competing interests. There’s no single compelling reason that justifies the twice-yearly disruption.
What Daylight Saving Time Does to Your Health
The health research on daylight saving time is one of the clearest arguments against keeping the current system.
Changing the clocks disrupts sleep. That might sound minor, but losing even one hour—particularly when it conflicts with your internal biological clock—has measurable effects. According to sleep experts at Johns Hopkins Bloomberg School of Public Health, the spring-forward transition is associated with acute increases in heart attack and stroke risk. A 2020 study found that the switch to daylight saving time raises the risk of fatal traffic accidents by 6%.
The problem runs deeper than a single bad night’s sleep. Moving clocks forward in spring pushes sunrise and sunset an hour later on the clock—but your body’s circadian rhythm doesn’t automatically adjust. The mismatch between your internal clock and your social clock (the time on your phone, your work schedule, your alarm) can persist for weeks.
For people already managing heart disease, sleep disorders, or mood-related conditions, the transition can be particularly disruptive. Adolescents are another vulnerable group: research published in the Journal of Clinical Sleep Medicine found that after the time change, students showed slower reaction times, reduced attention, and greater sleepiness during school hours.
People living on the western edges of time zones are at even higher risk of circadian misalignment, because they already get light later in the morning and evening relative to their clock time.
The Global Picture: Who Uses Daylight Saving Time—and Who Doesn’t
Daylight saving time is not universal. Roughly 70 countries worldwide observe some form of it, primarily in North America and Europe. Many countries near the equator don’t bother—because seasonal daylight variation is minimal, there’s little practical reason to shift the clocks.
Within the United States, Hawaii and most of Arizona have opted out entirely and remain on standard time year-round. Arizona’s case is particularly straightforward: with intense heat and desert climate, extra evening sunlight is not considered a benefit. The Navajo Nation within Arizona does observe daylight saving time, which creates its own geographic complexity.
Indiana was a notable holdout until 2006, when it became the 48th state to fully participate. Counties in the eastern time zone had previously been exempted.
Several US states have passed laws or resolutions supporting a move to permanent daylight saving time. As of 2025, 19 states have enacted such legislation or resolutions—including Texas, which passed supporting legislation in 2025. However, under current federal law, states can opt for permanent standard time but cannot unilaterally adopt permanent daylight saving time. That would require a change to federal law.
The Sleep Science Case for Permanent Standard Time
The ongoing debate isn’t simply about whether to keep clock changes—it’s about which time is healthier to stay on permanently.
Two proposals regularly appear in Congress. The Sunshine Protection Act, introduced multiple times since 2018, would make daylight saving time permanent. It passed the US Senate in 2021 but stalled in the House. The Sleep Research Society reports that 75% of Americans want to end the clock change altogether.
But there’s an important distinction between wanting to stop changing the clocks and choosing which time to lock in permanently.
The American Academy of Sleep Medicine (AASM) has taken a clear position: permanent standard time is the healthier choice. Their argument centers on circadian biology. Standard time—where solar noon (when the sun is highest in the sky) is closest to 12:00 PM on the clock—aligns better with the body’s natural sleep-wake cycle. Daylight saving time, by pushing clock time an hour ahead, creates a persistent mismatch between sunlight and social schedules that doesn’t go away just because the clocks stop changing.
“The Sunshine Protection Act would result in permanent misalignment of our internal clocks with the time on our social clocks,” says Dr. Adam Spira, a sleep expert and professor at Johns Hopkins. “That would be bad for the health of the US population.”
Exposure to morning light, which helps anchor the circadian rhythm and has an alerting effect on the brain, would be pushed later under permanent daylight saving time. That has real downstream consequences for sleep quality, mood, and cognitive performance.
Frequently Asked Questions
Why do we change the clocks twice a year?
The twice-yearly clock change exists because the original rationale for daylight saving time—shifting clocks forward in summer—was built around seasonal daylight variation. The idea was to match active waking hours with available daylight. Because that only applies during longer summer days, the clock change reverses in autumn. Without a federal law change, the US remains on this schedule.
Why is there still daylight saving time if the energy savings are minimal?
A combination of lobbying from industries that benefit from extra evening daylight (retail, hospitality, recreation), legislative complexity, and public familiarity has kept daylight saving time in place despite the weak energy evidence. There’s no single governing body making an ongoing cost-benefit calculation—the practice continues largely because changing it requires political will.
Why do some states not have daylight saving time?
Under the Uniform Time Act, states can opt out of daylight saving time and remain on standard time year-round. Hawaii and most of Arizona have done exactly that. States cannot, however, adopt permanent daylight saving time without a federal law change—which is why 19 states with permanent DST legislation are still waiting.
Is daylight saving time ending?
Not yet—but momentum is building. The Sunshine Protection Act has been introduced repeatedly, and a majority of Americans support ending the clock change. The scientific and medical community largely supports a switch to permanent standard time. Whether Congress acts is a different question.
Why do we have daylight saving time when it harms sleep?
When daylight saving time was created, the health effects of sleep disruption weren’t well understood. It was adopted as a wartime energy measure in 1916–1918 and later became embedded in law and habit. The research on circadian health consequences has grown substantially since then—which is a primary reason why medical organizations like the AASM are now calling for its elimination.
The Bottom Line
Daylight saving time was born out of wartime necessity, built on a logic that made sense in 1916 but has weakened considerably since. The energy savings are minimal. The health costs—disrupted sleep, elevated cardiovascular risk, impaired cognition during the transition—are real and documented. The farmer connection is a myth.
Whether you call it daylight saving or daylight savings time, the practice remains in flux. Most Americans want the clock changes to stop. Sleep scientists say the healthier path is permanent standard time. What happens next depends on Congress.
For now, the clocks keep changing—twice a year, like clockwork.
