The House, in a lopsided bipartisan vote, approved a measure Tuesday to make year-round daylight saving time the default for most of the United States beginning next year.

“This legislation does exactly what Americans have been asking Congress to do, not just for years, but decades: end outdated practices of changing our clocks twice a year by making daylight savings time permanent,” Rep. Kat Cammack (R-Fla.) said on the House floor Tuesday. “It also respects the choices of states that have already opted out of daylight savings time under current law.”

The measure passed by a vote of 308-117. A companion bill is still being debated in the Senate, where its prospects are uncertain.

Lawmakers in California and other states could opt out making daylight saving time permanent, but would need to decide before the law takes effect, Josh Gregory, a senior advisor to Rep. Vern Buchanan, the sponsor of H.R. 139, said in an email.

The debate over the year-round mandate centered on potential health issues and its impact on sleep, businesses, agriculture and outdoor recreation, particularly golf courses. President Trump, who owns several courses, supported the bill.

At a hearing Tuesday, Rep. Mary Gay Scanlon (D-Pa.) said the bill “chooses the wrong solution.” Its passage, she said, would mean “millions of Americans will wake up during the winter months in complete darkness, with the sun not rising until long after people get up and travel to school or work” and have a number of negative health impacts.

Most of the country went on daylight saving time in the spring, moving clocks one hour ahead of standard time. The bill would end the “fall back” to standard time that typically takes place in November. The change would mean darker mornings and later sunsets.

The debate over timekeeping has made its way to Capitol Hill before. In 2022, a bill to make daylight saving time permanent was approved by the Senate, but the effort stalled in the House.

It is unclear whether the current effort has enough support in the Senate to make it to the president’s desk. The Senate version of the bill, S 29, has 19 bipartisan sponsors, including Sen. Alex Padilla (D-Calif.). In a statement last year Padilla said, “More daylight after work means more business and more active, safer California communities.”

Areas that already do not observe daylight saving time would be able to stay on permanent standard time, according to the bill. For example, Arizona and Hawaii do not move their clocks forward or backward.

The effort has drawn support from both sides of the aisle. In California, Reps. Jay Obernolte (R-Big Bear Lake), Ken Calvert (R-Corona) and Young Kim (R-Anaheim Hills) are cosponsors of H.R. 139.

The proposal also has bipartisan opposition.

In a speech last year, Sen. Tom Cotton (R-Ark.) argued that while year-round daylight saving time might benefit some activities and areas — such as golfing in Florida and Alabama — residents of northern states and on the western sides of time zones might not see the sun rise until 9 a.m. in the winter.

Cotton raised concerns that students would need to walk to school in the dark and risk being struck by drivers, as was the case in 1974 when the U.S. briefly adopted year-round daylight saving time to combat an energy crisis.

“The darkness of permanent daylight saving time would be especially harmful for schoolchildren and working Americans,” Cotton said.

Rep. Nanette Barragán (D-San Pedro) said in a statement Monday that she planned to vote against the bill because “medical experts have warned that permanent daylight saving time is bad for our health.”

She supports a different proposal, the Sunshine for Our Kids Act, which seeks to make permanent standard time the default nationwide but gives states the ability to opt out. The bill, H.R. 9638, has been endorsed by the American Academy of Sleep Medicine.

Stanford professor Jamie Zeitzer, a physiologist who studies circadian cycles and how humans respond to light, supports ending the twice-a-year time changes.

The “spring forward” shift results in a loss of sleep and has been associated with a number of negative health effects, he said. The spring clock change has also been linked to more car accidents and cardiovascular incidents, he added.

Zeitzer’s research found that the darker mornings and brighter evenings of permanent daylight saving time weaken the circadian clock for many people.

“The abundance of biological evidence is clear that permanent standard time is a better solution,” Zeitzer said. “When you have a more robust light signal early in the morning, that will help keep your internal circadian system synchronized to the day.”

A 2025 AP-NORC survey found that the current system of changing the clocks twice a year is unpopular. According to the poll of nearly 1,300 U.S. adults, only 12% of respondents favored the current system, while 47% were opposed and 40% were neutral.

In the business world, there’s no consensus on making daylight saving time permanent. Many chambers of commerce and businesses that want to lure customers later in the day generally support it, while agricultural interests and some industries oppose it.

As for making standard time permanent, that faces opposition too.

Jay Karen, the chief executive officer of the National Golf Course Owners Assn., testified at a congressional hearing in November that losing extra evening daylight could cost the industry $1.6 billion in green fees alone because so many Americans tend to golf in the afternoon or evening.

Buchanan’s office said in a statement that the “well-documented benefits of having more sunshine later in the day after school and after work will be beneficial for millions of Americans’ health and well-being.”

There have been previous attempts to put an end to the twice-annual clock adjustments in California.

In 2018, California voters approved Proposition 7, which was supposed to give the Legislature the authority to impose year-round daylight saving time — but only if the federal government allowed states to do so. It has not yet led to any meaningful change.

Earlier this year, state Sen. Roger Niello (R-Fair Oaks) introduced S.B. 1197, which seeks to “ditch the switch” by moving the state to permanent standard time.

A spokesperson for Niello’s office said that because his previous efforts failed to gain traction, his current proposal includes a provision requiring California to conform if the federal government adopts permanent daylight saving time.

Even if states can opt out, it’s not clear that California would try to pursue that route. Niello’s spokesperson said in a text that many Sacramento legislators more focused on getting rid of the time switches than on which system becomes permanent.