Daylight saving time was originally adopted to shift an extra hour of sunlight into the evening, giving people more usable daylight after work. The idea dates back to the 1890s, and governments around the world embraced it during wartime to conserve energy. Today, the practice continues mostly out of institutional inertia, even as mounting evidence suggests the twice-yearly clock change causes more problems than it solves.
How the Idea Started
The first serious proposal for shifting clocks came from George Hudson, a New Zealand entomologist who worked as a mail clerk by day. His day job ate into the sunlight hours he needed to collect insects, his lifelong passion. In 1895, he proposed shifting clocks forward by two hours during summer months so people could enjoy more daylight in the evening.
The concept didn’t gain political traction until World War I, when Germany adopted it in 1916 to reduce coal consumption for lighting. Britain, the United States, and other nations quickly followed. The logic was straightforward: if people are awake during more sunlit hours, they burn less fuel on artificial light. The U.S. dropped it after the war, brought it back during World War II, and then left it up to individual states until 1966, when the Uniform Time Act standardized the practice nationally.
The Energy Argument Has Weakened
Energy savings were the original policy justification, but the math has changed dramatically since 1916. Back then, lighting was the dominant household energy expense. Today, heating and air conditioning dwarf lighting costs, and LED bulbs use a fraction of the electricity that incandescent bulbs did. Studies examining modern energy use have found the savings from daylight saving time are negligible, sometimes even negative. When people get home with an extra hour of sunlight and warmth, they’re more likely to drive somewhere, run the air conditioning, or otherwise consume energy in ways that offset any lighting savings.
What the Time Change Does to Your Body
Your body runs on an internal clock that relies heavily on light exposure. When darkness falls, specialized cells in your eyes send signals to your brain, which triggers the release of melatonin, the hormone that makes you sleepy. Melatonin levels naturally rise after sunset, peak between 2 and 4 a.m., and taper off toward morning. This cycle is tightly calibrated, and even a one-hour shift can throw it off.
In spring, when clocks jump forward, you lose an hour of morning light and gain an hour of evening light. That extra evening brightness delays your melatonin release, making it harder to fall asleep at your usual time. But your alarm still goes off at the same number on the clock, so you’re effectively sleep-deprived. Most people adjust within a few days, but the transition week is measurably harder on the body. The fall change is gentler because you gain an hour, though the sudden shift to earlier darkness in the evening brings its own problems.
Health Risks During the Transition
The spring clock change is linked to a real, measurable spike in heart attacks. A study published in the New England Journal of Medicine found that heart attack incidence increased by about 5% during the first week after the spring transition. The effect was strongest in the first three weekdays, when the combination of lost sleep and disrupted circadian rhythm puts extra stress on the cardiovascular system.
Traffic safety takes a hit too. Research on U.S. crash data found a significant increase in fatal car accidents on the Monday immediately following the spring shift. Sleep deprivation, even losing just one hour, slows reaction times and impairs judgment in ways that show up clearly on the roads.
The fall transition carries a different kind of risk. A Danish study analyzing over 185,000 hospital contacts for depression found that the autumn shift back to standard time was associated with an 11% increase in depressive episodes. The effect took roughly 10 weeks to fully dissipate. The sudden loss of evening daylight appears to act as a trigger for people already vulnerable to depression, compounding the seasonal reduction in light that happens naturally as winter approaches.
Farmers Never Wanted It
A common misconception is that daylight saving time was created for farmers. In reality, agricultural communities have consistently opposed it. Farmers follow the sun, not the clock. Crops need dew to evaporate before harvest, and livestock operate on biological schedules that don’t adjust to arbitrary time changes.
Dairy cows, for example, are accustomed to being milked at the same time every day. When clocks shift, the cows don’t understand why milking suddenly comes an hour earlier or later. A delayed milking in fall can cause discomfort and disrupt production. Meanwhile, the milk truck still arrives on clock time, because distributors operate on schedules. This mismatch forces dairy farmers into awkward workarounds twice a year. Farmworkers face similar problems: if they have to wait an extra hour for daylight before they can start working in the morning but still leave at the same clock time in the evening, less work gets done.
Why It Still Exists
If the energy savings are minimal and the health costs are real, the obvious question is why we still do this. The short answer is that governments have struggled to agree on what to replace it with. Everyone wants to stop changing clocks, but the debate over whether to lock in permanent daylight saving time or permanent standard time has stalled progress.
In the U.S., the Sunshine Protection Act, which would make daylight saving time permanent year-round, has been introduced in Congress multiple times. The most recent version was referred to the House Committee on Energy and Commerce in January 2025, but it hasn’t advanced further. A previous version passed the Senate unanimously in 2022, then died in the House without a vote.
The European Union has hit a similar wall. The European Parliament voted in 2019 to end seasonal clock changes, but the Council of the EU, where member states must reach agreement, has never adopted a position. No timeline for a decision has been set. The sticking point is that each country would need to choose which time to keep permanently, and neighboring countries landing on different choices could create a patchwork of time zones across Europe.
So daylight saving time persists not because anyone has made a strong case for continuing it, but because the political mechanics of replacing it are surprisingly difficult. The twice-yearly ritual continues, largely on autopilot, while legislatures debate which version of the clock to keep.