Daylight saving time exists to shift an hour of morning sunlight to the evening, giving people more usable daylight after work and school. The idea dates back to 1907, and while it was originally pitched as a way to stop wasting summer mornings, its survival over the past century has had more to do with economics, wartime energy policy, and lobbying than any single practical benefit. Today, about 70 countries observe some form of DST, though the practice is increasingly controversial.
Where the Idea Came From
A British builder named William Willett, who was also an avid horse rider, first proposed the concept in 1907. Frustrated by what he called the “waste of daylight” on spring and summer mornings, Willett suggested advancing clocks by 20 minutes on each of four Sundays in April, then reversing the process across four Sundays in September, for a total shift of 80 minutes. The British Parliament debated his proposal but never passed it during his lifetime.
Germany became the first country to actually adopt the idea in 1916, during World War I, as a fuel-saving measure. The United States followed in 1918 for the same reason. After the war ended, the U.S. quickly repealed it due to widespread unpopularity, and it didn’t return nationally until World War II. The version Americans follow today was standardized by the Uniform Time Act of 1966, though individual states can opt out (Arizona and Hawaii do).
The Farmer Myth
One of the most persistent misconceptions is that daylight saving time was created to help farmers. The opposite is closer to the truth. The agriculture industry has historically lobbied against DST because farming runs on sunlight, not clocks. A dairy cow used to being milked at 5 a.m. doesn’t adjust when the clocks change. Her production schedule gets thrown off, but the milk truck still arrives on clock time, leaving farmers no choice but to deal with the mismatch.
Farmworkers face a similar problem. During DST, they have to wait an extra hour for enough daylight to start working in the morning, but they still leave at the same clock time in the evening. That means less total work gets done. As one member of Congress from a farming district put it: “Farmers rely on the sun to determine their schedule, not their clocks.”
Who Actually Benefits
The industries that have pushed hardest to keep (and extend) daylight saving time are the ones that profit from people being outdoors after work. In the 1980s, golf industry lobbyists told Congress that an extra month of DST would generate $200 million more per year in club sales and green fees. The barbecue industry made a similar case in 1986, estimating $100 million in additional annual revenue from grill and charcoal sales. Retailers, restaurants, and tourism businesses all see more foot traffic when it stays light until 8 or 9 p.m.
There’s also a measurable effect on crime. A Stanford study found that robbery rates drop by an average of 51% during the sunset hour after clocks spring forward, because the extra evening light removes the cover of darkness that opportunistic criminals rely on.
What It Does to Your Body
Your internal clock, or circadian rhythm, is set primarily by light exposure. When clocks spring forward, you lose morning light and gain evening light. Both changes push your body’s natural rhythm later, making it harder to fall asleep at your usual time and harder to wake up the next morning. In effect, DST creates a mild form of jet lag that, for many people, lingers for days or even weeks.
The American Academy of Sleep Medicine has noted that this shift causes a phase delay: your biology wants to sleep and wake later, but your work and school schedule still demands the same early start. The result is accumulated sleep loss on top of circadian misalignment. This isn’t just an inconvenience. It has measurable health consequences.
A study using hospital data from Indiana found a 27.2% increase in heart attack admissions following the spring transition. That elevated risk persisted for roughly two weeks and showed no sign of adaptation over the years studied, meaning people don’t simply “get used to it” with repeated exposure. The fall transition, when clocks move back, does not produce a corresponding decrease that offsets the spring spike.
Traffic safety follows a similar pattern. Research from the Insurance Institute for Highway Safety found that fatal crashes among vehicle occupants increase by 12% in the five weeks after the spring change. The fall transition, by contrast, sees a 7.1% decrease in those same crashes. Pedestrian and cyclist fatalities move in the opposite direction, rising in fall when evening darkness arrives earlier.
The Push to Stop Changing Clocks
Public frustration with the twice-yearly time change has fueled legislative efforts to pick one time and stick with it. The U.S. Senate unanimously passed the Sunshine Protection Act in 2022, which would have made daylight saving time permanent year-round, but the bill stalled in the House. A new version, the Sunshine Protection Act of 2025, was introduced in January 2025 and would do the same thing.
Sleep scientists generally disagree with the choice of permanent DST. The American Academy of Sleep Medicine’s official position favors permanent standard time instead, arguing that standard time more closely aligns with the natural light cycle and would reduce the chronic circadian misalignment that DST creates. Under permanent DST, winter sunrises in some northern cities wouldn’t happen until nearly 9 a.m., meaning many people would commute, and children would wait for school buses, in complete darkness.
How the Rest of the World Handles It
Most countries on Earth don’t observe daylight saving time at all. Of the roughly 248 countries and territories tracked globally, 178 have no DST. China, Japan, India, and most of Africa and Southeast Asia never change their clocks. The practice is concentrated in Europe, North America, and parts of South America and the Middle East, though the list keeps shrinking. The European Union has been debating the elimination of clock changes since 2019, and countries like Russia, Turkey, and Brazil have already dropped it in recent years.
Countries near the equator have little reason to consider DST because their day length barely changes across seasons. The further you are from the equator, the more dramatic the seasonal swing in daylight, which is why the practice has historically been most common in northern latitudes where summer evenings can stretch past 9 p.m. and winter days feel painfully short regardless of what the clock says.