Congress, sleep experts at odds over permanent daylight saving time

Most Americans set their clocks forward one hour this weekend for daylight saving time, part of the twice-yearly time shift that has been happening since the 1960s. 

Some members of Congress want to put an end to the biannual time change by cementing daylight saving time year-round, while some sleep experts have lobbied for the U.S. to ditch daylight saving time in favor of permanent standard time.

A bipartisan, bicameral bill called the Sunshine Protection Act that has been routinely reintroduced by Sen. Marco Rubio (R-Fla.) would make daylight saving time permanent, ending the biannual ritual of “springing forward” in March for daylight saving time and “falling back” in November to standard time.

The Sunshine Protection Act would allow the states that currently observe permanent standard time — Hawaii, most of Arizona and the U.S. territories — to remain on year-round standard time.

Nearly two-thirds of Americans said they were in favor of ending the clock changes, according to an Economist/YouGov poll of 1,000 adults last March. Of those who favored ending the time change, half said they favored year-round daylight saving time as opposed to 31 percent who preferred standard time.

Federal law currently prevents states from unilaterally making daylight saving time permanent. However, 19 states have enacted legislation or passed resolutions to greenlight permanent daylight saving time if Congress approved the change, according to the National Conference of State Legislatures.

Rubio has called the biannual clock change “antiquated” and consistently introduced the Sunshine Protection Act each Congress since 2018. The bill, which passed the Senate but died in the House last Congress, has stalled since it was introduced last spring following the start of the new Congress.

Proponents of permanent daylight saving time have pointed to research that shows the biannual ritual may not just be outdated, but could also have a negative impact on Americans’ health and safety. 

Studies have linked changing times with an uptick in fatal car crashes, emergency room visits, missed appointments, heart attacks and strokes. 

Traffic fatalities spiked 6 percent during the five workdays following the spring time change, according to a 2020 study of fatal motor vehicle accidents between 1996 and 2017 published by Current Biology. Heart attacks jumped 24 percent on the Monday after the spring shift to daylight saving time, according to a 2014 study published in Open Heart, which also found heart attacks dropped 21 percent following the fall shift to permanent standard time.

Research has shown that the populations that are most at risk during the transition to daylight saving time are people with insomnia, teens and students, night owls and sleep-deprived individuals — the latter accounting for one-third of the U.S. population, according to the Centers for Disease Control and Prevention. 

“It’s time to lock the clock. Floridians are sick of changing their clocks because we all want more sunshine. It’s time for Congress to act, and I’m proud to be leading the bipartisan Sunshine Protection Act with Senator Rubio to get this done,” said Sen. Rick Scott (R-Fla.), one of the bill’s co-sponsors, ahead of this year’s time change.

There are 17 co-sponsors on the current version of the Senate bill, according to Congress.gov, including Sens. Scott, James Lankford (R-Okla.), Alex Padilla (D-Calif.), Tommy Tuberville (R-Ala.), Ed Markey (D-Mass.), Bill Hagerty (R-Tenn.), Tina Smith (D-Minn.), Cindy Hyde-Smith (R-Miss.), Rand Paul (R-Ky.) and Ron Wyden (D-Ore.).

Rep. Vern Buchanan (R-Fla.) has also introduced a companion bill in the House. The House bill currently has 34 co-sponsors, including Democratic Reps. Brendan Boyle (Pa.), Dean Phillips (Minn.) and Steve Cohen (Tenn.).

“Changing our clocks twice a year is inconvenient and entirely unnecessary. It’s time to end this antiquated practice and pass my bill with [Rubio] to make daylight savings time permanent,” Buchanan wrote on X, the platform formerly known as Twitter.

Both the American Academy of Sleep Medicine (AASM) and the National Sleep Foundation have advocated for the elimination of the biannual time changes, citing the impact of an abrupt time change on well-being.

But rather than backing the push for permanent daylight saving time, these sleep experts support a shift to permanent standard time.

While daylight saving came about to add an hour of sunshine to the end of the day, it does so at the expense of an hour of sunshine in the morning. Kin M. Yuen, an AASM spokesperson and sleep medicine specialist at the University of California, San Francisco, told The Hill that morning sunlight is “quite important.” 

“Lack of sunlight and the cues to tell us that ‘this is morning, we should be wide awake’ is leading to undoubtedly a lot of difficulties that we have with motivation, with alertness, with cardiovascular outcomes,” Yuen said.

The AASM’s stated position, updated in January 2024, is that year-round standard time better aligns with the natural circadian rhythm, while delayed sunlight during daylight saving could lead to circadian misalignment.

It takes some people longer to adjust to daylight saving time, studies show. A 2021 study published in Scientific Reports found the body clocks of “genetically predisposed evening-inclined individuals” — i.e. night owls — slept “significantly less” on work nights following the transition and had not adjusted to daylight saving time one week after the shift.

The Sleep Research Society, American Medical Association (AMA) and other professional societies also called for an end to daylight saving time, echoing sleep experts who say the change would lead to better health and safety outcomes.

“Eliminating the time changes in March and November would be a welcome change. But research shows permanent daylight saving time overlooks potential health risks that can be avoided by establishing permanent standard time instead,” said AMA trustee Alexander Ding, a physician and associate vice president for physician strategy and medical affairs at Humana, ahead of this year’s clock change.

“Sleep experts are alarmed. Issues other than patient health are driving this debate. It’s time that we wake up to the health implications of clock setting.”

Yuen also attributes the current push for year-round daylight saving time to “national amnesia.” Although the U.S. did previously adopt permanent daylight saving time in 1973, it was repealed following public pushback just one year later.

“We tend to be rather short-sighted in ‘gaining’ sunlight for an hour during the day in the spring and the summer months,” Yuen said.