As Congress debates making Daylight Saving Time permanent, Mexico’s four-year experiment offers valuable lessons about health, safety, energy savings, and border communities.
Every spring and every fall, millions of Americans perform the same ritual.
They change the clocks.
Some welcome the extra evening sunlight. Others dread losing an hour of sleep. Parents worry about getting children ready in the dark, while commuters adjust to changing sunrise times. Most Americans, regardless of political affiliation, agree on one thing: changing the clocks twice each year is inconvenient.
Now Congress is once again trying to end that ritual.
The U.S. House of Representatives recently passed the Sunshine Protection Act of 2025 (H.R. 139) by an overwhelming bipartisan vote of 308-117, proposing to make Daylight Saving Time permanent across most of the country.
If the measure eventually becomes law, Americans would stop changing their clocks every March and November.
But before lawmakers decide whether to lock the nation into permanent Daylight Saving Time, there is one country whose experience deserves close attention.
Mexico has already done something similar—but not in the way many Americans assume.
Instead of adopting permanent Daylight Saving Time, Mexico abolished seasonal clock changes for most of the country and adopted permanent Standard Time in 2022.
Nearly four years later, its experience has become one of the world’s most valuable real-world case studies on what happens after ending the twice-a-year time change.
The lessons are both encouraging and cautionary.
While Mexico has seen benefits related to health and public safety, it has also encountered unexpected economic complications—particularly in communities along the U.S. border.
For California, whose economy, workforce, and families are deeply connected with Mexico, those lessons are especially relevant.
Although the House overwhelmingly approved the Sunshine Protection Act, the proposal is far from becoming law.
The Senate remains deeply divided.
Ironically, the biggest disagreement is no longer whether Americans should stop changing their clocks.
It is which clock Americans should keep permanently.
Supporters of the House bill argue that permanent Daylight Saving Time would provide:
- More daylight after work
- Increased outdoor recreation
- Higher retail spending
- Greater tourism activity
- More evening time for families
President Donald Trump has publicly endorsed ending the seasonal clock changes and has said he would sign legislation reaching his desk.
But many senators remain unconvinced.
Among the strongest critics are lawmakers who warn that permanent Daylight Saving Time would leave millions of children waiting for school buses before sunrise during the winter months.
In some northern states, sunrise could occur close to 9 a.m.
That concern has become one of the Senate’s biggest obstacles.
The Medical Community Wants Something Different
One of the biggest surprises in this debate is that many health experts oppose the House bill-not because they want to keep changing the clocks, but because they believe Congress has chosen the wrong permanent option.
The American Academy of Sleep Medicine has recommended permanent Standard Time, arguing that it aligns more closely with the body’s natural circadian rhythm. Sleep researchers have linked seasonal clock changes to disruptions in sleep, increased risks of heart attacks and strokes shortly after the spring transition, workplace injuries, and reduced alertness.
For these experts, the goal is not simply to end the clock changes. It is to adopt the time standard they believe best supports long-term health.
That distinction often gets lost in the political debate.
Then Mexico Changed the Clocks
While Washington continues debating, Mexico has already conducted the experiment.
In October 2022, Mexico officially eliminated Daylight Saving Time across most of the country.
The decision came after years of public frustration and a government review that concluded the policy produced little measurable benefit.
Rather than extending Daylight Saving Time throughout the year, Mexico chose permanent Standard Time.
It was a decision driven less by convenience than by health and scientific evidence.
The move received broad public support. National surveys at the time found that about seven in ten Mexicans favored ending the twice-yearly clock changes.
Unlike the United States, where political debate often centers on enjoying longer evenings, Mexico framed the issue around biological health, sleep quality, and limited energy savings.
Four years later, researchers continue examining the results.
Lesson One: The Energy Savings Were Smaller Than Many People Expected
When Daylight Saving Time was first introduced decades ago, one of its main goals was reducing electricity use by extending evening daylight.
That logic made sense in an era when lighting represented a significant share of household electricity consumption.
Today’s energy habits look very different.
Air conditioning, refrigeration, computers, streaming devices, data centers, and home electronics consume far more electricity than lighting alone.
Before ending Daylight Saving Time, Mexico’s government reviewed national energy data and concluded that the seasonal time change produced only modest electricity savings, with little meaningful impact on household utility bills.
Those findings mirror research from universities in the United States suggesting that the original energy-saving justification for Daylight Saving Time has weakened over time.
For many energy experts, the debate has shifted from saving electricity to balancing public health, transportation safety, business needs, and quality of life.
Lesson Two: Health Became the Strongest Argument
Perhaps the most significant lesson from Mexico is that the discussion gradually shifted away from clocks and toward sleep.
Researchers studying circadian rhythms have long argued that human biology responds more naturally to Standard Time because it more closely matches the position of the sun.
By reducing disruptions caused by seasonal clock changes, scientists believe societies may lower long-term risks associated with chronic sleep deprivation.
Mexico cited these health considerations as one of the principal reasons for ending Daylight Saving Time.
Subsequent academic research has continued exploring how permanent Standard Time may improve sleep alignment and reduce some health risks associated with repeatedly shifting the clock.
That scientific debate is now influencing lawmakers in the United States as well.
Lesson Three: Fewer Clock Changes May Mean Safer Roads
For years, researchers have observed a troubling pattern following the start of Daylight Saving Time each spring.
When people lose an hour of sleep, the effects can extend beyond feeling tired. Studies in the United States and other countries have found increases in workplace injuries, reduced productivity, and a temporary rise in traffic crashes in the days immediately after the clocks change.
That has led many sleep experts to argue that the greatest benefit may not come from choosing one time system over another, but from eliminating the twice-yearly disruption altogether.
Mexico’s experience appears to support that argument.
Historical data from Mexico showed increases in fatal traffic crashes during clock-change periods before the country abolished Daylight Saving Time. By eliminating those transitions for most of the country, officials also eliminated the seasonal disruption associated with changing the clocks.
Researchers caution that traffic safety depends on many factors, including weather, road conditions, driver behavior, and enforcement. Even so, many transportation and public health experts view the elimination of clock changes as one way to reduce a known source of sleep-related risk.
For Californians, where millions of people commute long distances every day, even modest improvements in alertness could have meaningful public safety benefits.
Lesson Four: Mexico’s Biggest Challenge Wasn’t Health. It Was the Border.
If Mexico’s experience offers encouragement for ending seasonal clock changes, it also provides a warning.
The country’s largest challenge was not adjusting to a new time system. It was staying synchronized with its biggest trading partner.
When Mexico ended Daylight Saving Time in 2022, communities along the northern border suddenly found themselves operating on different schedules than neighboring U.S. cities.
The effects were immediate.
Manufacturers had to coordinate different operating hours. Trucking companies adjusted delivery schedules. Government agencies revised office hours. Families living on opposite sides of the border found school, work, and appointments occurring an hour apart.
The disruption was significant enough that Mexico revised its policy.
Today, the entire state of Baja California and dozens of municipalities in Chihuahua, Coahuila, Nuevo León, and Tamaulipas continue changing their clocks to remain aligned with neighboring U.S. communities.
That exception underscores an important lesson: even when a time policy makes sense domestically, international trade can require flexibility.
Why California Should Be Paying Close Attention
No state has more at stake in this debate than California.
California and Mexico share one of the busiest international economic relationships in the world. Every day, billions of dollars in goods move through border crossings connecting California with Baja California.
Thousands of workers cross the border for employment, education, health care, and family obligations.
Southern California businesses coordinate daily with companies in Tijuana and Mexicali. Manufacturers rely on just-in-time supply chains. Hospitals, universities, logistics companies, and government agencies routinely collaborate across the border.
If the United States eventually adopts permanent Daylight Saving Time while most of Mexico remains on permanent Standard Time, California could experience seasonal scheduling differences with many regions of Mexico.
Although Baja California currently follows U.S. clock changes to preserve economic integration, policymakers on both sides of the border would likely need to evaluate how any future U.S. changes affect commerce and daily life.
What It Could Mean for Los Angeles Families
For many residents of Los Angeles County, the debate is not simply about daylight. It is about daily routines.
Parents think about school drop-offs.
Construction workers begin shifts before sunrise.
Health care employees work overnight schedules.
Delivery drivers and warehouse workers often report to work long before dawn.
Permanent Daylight Saving Time could provide brighter evenings for outdoor recreation, youth sports, shopping, and restaurants. Many businesses argue that additional evening daylight encourages economic activity and gives families more time outside after work.
But those benefits come with tradeoffs.
During winter months, sunrise would occur later than it does under permanent Standard Time. Depending on location and time of year, many children could begin traveling to school before sunrise, while commuters would spend more time driving in darkness.
Supporters and opponents of permanent Daylight Saving Time generally agree on one point: the twice-yearly clock change is disruptive. Their disagreement centers on which tradeoff Americans should accept.
What Latino Communities Should Know
For many Latino families in California, this debate has another dimension that receives little national attention.
Strong family, cultural, and business ties connect communities across California and Mexico.
Changes in time schedules can affect:
- Cross-border workers.
- Families planning phone calls or video chats with relatives.
- Small businesses coordinating deliveries.
- Truck drivers transporting goods across the border.
- Medical appointments involving providers in both countries.
- Students participating in educational exchanges.
- Employers managing teams in both countries.
If the United States changes its time policy while Mexico maintains its current system, some of these routine activities could require additional coordination.
That does not necessarily mean the policy would be harmful. But it illustrates why California’s perspective may differ from states located far from the international border.
The Sunshine Protection Act has cleared the House of Representatives, but its path forward remains uncertain.
The Senate could:
- Approve the House bill.
- Amend it to favor permanent Standard Time.
- Decline to bring it to a vote.
- Delay consideration indefinitely.
Unless Congress passes legislation and the president signs it into law, the current system remains in effect.
For now, Americans should still expect to change their clocks this fall.
The Bigger Lesson
Mexico’s experience shows there is no perfect solution.
Ending the twice-yearly clock change appears to offer meaningful benefits for sleep, public health, and convenience.
At the same time, the experience also demonstrates that time policies do not exist in isolation. They affect international trade, transportation, schools, businesses, and families.
As Congress debates the future of Daylight Saving Time, lawmakers are not making a decision in the dark.
They have a neighboring country that has already tested one approach.
The question now is not whether Americans dislike changing their clocks. Polls consistently suggest many do.
The real question is which system best balances health, safety, economic activity, and everyday life.
For California, where international commerce and cross-border communities are part of daily life, that answer may be more complex than it first appears.
