Why does the US have daylight saving time? A look at efforts to ‘lock the clock.’

Every March, Americans lose an hour of sleep as clocks spring forward to mark the start of daylight saving time. That they get an extra hour to rest in November when clocks shift back to standard time doesn’t lessen the grumbling from those who find the decades-old practice disruptive.

But could time be up for the biannual clock switches? In early January, Republican Sen. Rick Scott of Florida reintroduced a bill to “lock the clock” by making daylight saving time year-round; clocks wouldn’t be turned back in the fall.

Mr. Scott’s Sunshine Protection Act is the latest salvo in a long-running back-and-forth about the value of tinkering with the clocks. In 2022, the Senate passed a bill by the same name by unanimous consent, but it stalled in the House. Before taking office, President Donald Trump had signaled support for ending the time shifts.

Here’s a look at the history of daylight saving time in the United States and some efforts underway to end “spring forward, fall back.”

When and why was daylight saving created?

The premise of daylight saving time is simple: Setting clocks forward in the spring, when days are lengthening, allows people to take advantage of daylight in the evening rather than sleeping through it in the morning. That idea goes back to Benjamin Franklin, according to David Prerau, who studied daylight saving time for the federal government and wrote the book “Seize the Daylight.”

While living in Paris in 1784, the founding father observed that he could save on candle wax by waking up an hour earlier. Near the turn of the 20th century, George Vernon Hudson, a British-born New Zealand entomologist, and William Willett, a British builder, separately suggested shifting clocks forward using logic similar to Franklin’s.

The idea didn’t become policy in the U.S. until the world wars. In both conflicts, the U.S. temporarily adopted daylight saving time to save fuel. Eventually, the Uniform Time Act of 1966 established nationwide daylight saving time.

What are some arguments for and against the time changes?

Proponents of yearlong daylight saving time argue that extra sunlight in the evening slashes energy use and gives people more time to spend outdoors. Some studies have found that daylight saving time lowers crime rates in the evenings. And retailers say that consumers spend less after the clocks shift back in the fall.

Yet it’s not clear that pushing clocks forward saves much electricity. A 2008 report by the Department of Energy examined a roughly one-month lengthening of daylight saving time and found that it reduced electricity consumption by only 0.5% daily. Other studies have not found any positive impact, and some suggest that daylight saving time might actually increase energy use.

The U.S. has also tried permanent daylight saving time before. It didn’t go well.

In December 1973, amid a nationwide energy crisis, Congress made daylight saving time permanent to save fuel. About 57% of Americans supported the measure, according to Gallup.

That was no longer the case come January. With the sun rising after 8:30 a.m. in much of the country, commuters lamented the change. Parents protested as children walked to bus stops and school in the dark. Broad discontent, and concerns about safety after several early morning traffic deaths, pushed Congress to repeal the law after 10 months.

Many sleep experts have called for transitioning to permanent standard time, which would avoid dark mornings but push summer sunrises to as early as 3:45 a.m. in some places.

“A shift toward permanent daylight saving time ... could disrupt our sleep in the sense of not aligning with our typical circadian rhythms,” says Tony Cunningham, the director of the Center for Sleep and Cognition at Beth Israel Deaconess Medical Center in Boston.

While polling conflicts on whether Americans prefer year-round standard time or daylight saving time, most people seem to agree that they don’t want to keep switching the clocks. A 2022 YouGov survey found that 62% of respondents wanted to axe the practice.

In 2020, the American Academy of Sleep Medicine issued a position statement linking the spring clock transition to an increased risk of car accidents, mood disorders, and adverse cardiac events. Dr. Cunningham says that although most sleep researchers advocate for year-round standard time, anything would be better than the biannual switches. “The change is essentially forcing jet lag on the entire United States population,” he says.

Mr. Prerau points out that in 2024, a study of over 36 million adults found only a slight uptick in adverse cardiac events during the week after the spring and fall transitions to daylight saving time – a result the authors said was not clinically significant. Some studies, too, have found that the transition causes only a small number of traffic deaths.

What is Mr. Trump’s position on daylight saving time?

Mr. Trump made headlines in December with a post on his social media platform, Truth Social, that weighed in on the debate.

“The Republican Party will use its best efforts to eliminate Daylight Saving Time, which has a small but strong constituency, but shouldn’t! Daylight Saving Time is inconvenient, and very costly to our Nation,” Mr. Trump wrote.

The post came after Elon Musk, Mr. Trump’s choice to lead the new Department of Government Efficiency (not a true federal department), posted on the platform X that he wanted to end the clock switches.

Mr. Trump’s post seems to conflict with the efforts of lawmakers who have pushed to make daylight saving time permanent. It also is at odds with some of Mr. Trump’s past statements.

In 2019, Mr. Trump posted on what was then Twitter that “Making Daylight Saving Time permanent is O.K. with me!” It’s possible that in his December 2024 post Mr. Trump was using “daylight saving time” colloquially, as many do, to refer to the biannual clock switches.

What efforts are underway to end the time changes?

States currently can opt to use standard time year-round, and Hawaii and Arizona (with the exception of the Navajo Nation) already do so. But using daylight saving time all year requires an act of Congress.

The most recent iteration of the Sunshine Protection Act would also allow states to opt for standard time instead, lawmakers say. At least 20 states have passed legislation that would put them on permanent daylight saving time should a federal law allow it.

The bill has built unusual alliances and might be able to overcome typical partisan divisions. It’s sponsored by a coalition of Republicans and Democrats, including close Trump ally Senator Scott as well as Sen. Ed Markey, a liberal Massachusetts Democrat. Still, similar measures have failed before.

As Congress mulls the legislation, Mr. Prerau suggests that Americans could ease the spring forward in March through preparation.

“One hour of clock change is no different than going from Chicago to New York,” he says. “And people do that all the time. ... If they plan for it, like a traveler would, [Americans] can minimize their problems.”