It’s time to fall back.
The clock will strike 1 a.m. twice on Sunday morning as Daylight Savings Time comes to an end.
Here’s what you need to know about Daylight Savings Time and why the U.S. changes its clocks twice a year.
When does daylight saving time end?
Daylight Saving Time began on March 10 and ends on November 3.
Unlike in the spring, when we lose an hour and the clocks skip 2 hours altogether, we get an extra hour on Sunday, with the clocks jumping back from 1:59 a.m. to 1:00 a.m.
The sun will also set earlier in the U.S. as temperatures continue to cool and we head into the late fall and winter month
Why is this happening?
The practice, which was established in 1918 by the Standard Time Act, is an attempt to extend daylight hours in the summer by delaying sunset by an hour, according to the U.S. Astronomical Applications Department.
Daylight saving time, a controversial idea when it was first adopted, was quickly repealed in 1919 and became a local matter. It was reinstated during the early days of World War II and observed from 1942 to 1945, the department said.
After the war, the implementation of daylight saving time varied from state to state until the Uniform Time Act was passed in 1966, which standardized the dates of daylight saving time but allowed local exemptions if states or municipalities did not want to participate.
According to the department, the standardized start and end dates have changed over the years, but since 2007, daylight saving time begins on the second Sunday in March and ends on the first Sunday in November.
How long does standard time last?
Standard time in the U.S. will remain the same, along with earlier sunsets and darker evenings, until spring arrives and Daylight Savings Time begins again.
In 2025, Daylight Savings Time will begin on Sunday, March 9 and end on Sunday, November 2, when it will be time to repeat the process.
Are there any states that don’t observe?
Yes, according to the Division of Astronomical Applications, Hawaii and most of Arizona do not observe Daylight Savings Time and therefore do not change their clocks twice a year.
Is the U.S. the only country that does this?
No, most countries observe some version of “daylight saving time,” the department said. In the Northern Hemisphere, most countries that observe daylight saving time are in Europe and North America.
While other countries do observe some version of daylight saving time, they don’t all do so on the same schedule as the U.S.
There are also countries in the Southern Hemisphere that observe some version of daylight saving time, but below the equator, the seasons are reversed, so the start and end dates of their “daylight saving time” are reversed from ours, the department said.
According to the Pew Research Center, only about a third of all countries observe daylight saving time. At one point, about half of all countries observed the practice, but they no longer do.
What efforts have been made to end the practice?
In March 2022, the U.S. Senate passed the Sunshine Protection Act, which would permanently implement year-round Daylight Saving Time and end the era of having to change our clocks.
Under the bill, Hawaii and most of Arizona would remain on standard time year-round.
But the bill has since stalled in the House of Representatives, meaning the U.S. will remain on the time change until it passes that chamber and is then signed by the sitting president.
Nearly all states have considered legislation to maintain standard time or daylight saving time, and 20 states have passed bills or resolutions to implement year-round daylight saving time in the past six years, according to the National Conference of State Legislatures. But because federal law does not currently allow for year-round daylight saving time, states would have to wait until Congress passes the bill to implement the change.
What do health experts say?
Some research suggests that using Daylight Saving Time year-round could reduce traffic accidents and crime.
But some experts are not in favor of permanent Daylight Saving Time. That’s because sleep experts say the sun should reach its highest point in the sky at noon, known as solar time.
During standard time, people in the U.S. Central Time Zone are perfectly aligned with solar time, but during Daylight Saving Time, they are pushed further away from that clock.
The more mismatched with solar time, the greater the risk of health problems, Dr. Karin Johnson, a neurology professor at UMass Chan Medical School-Baystate who serves on the board of Save Standard Time, a nonprofit that advocates for permanent standard time, told News in 2022.
Sleep experts favor the back-and-forth of the clocks over permanent Daylight Saving Time. When people wake up in the dark, hormones like cortisol can be higher, which can make people feel sleepier, said Dr. Kin Yuen, a sleep medicine specialist at the University of California, San Francisco, and a fellow at the American Academy of Sleep Medicine, in 2022.
Because the sun shines later, people may go to sleep later during daylight saving time, which can slow the body’s production of melatonin.
In addition, a June 2022 study found that people whose clock times do not closely align with the sun had 22% higher traffic fatality rates than people who lived within 30 minutes of the sun’s time.