Morning in America could, someday soon, be earlier than ever imagined.
President-elect Donald Trump vowed to end daylight savings time, a surprising pledge that, if carried through, would dramatically alter U.S. life in spring and summer months when Americans revel in sunshine well into traditional nighttime hours.
Daylight savings time tends to push sunshine to later hours, making for gloriously long, bright days in spring and summer months. Standard time brings more sunshine to earlier hours, insuring that children are not trudging to school in cold-weather darkness.
Trump’s proposed sunset of daylight savings time, a practice long believed to be supported by U.S. business interests, stunned the medical community that’s been pushing for years to make standard time full-time. Opponents of daylight savings say it can pose a risk of mood disorders, adverse cardiovascular events and car crashes.
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University of California San Francisco neurologist and sleep expert Dr. Kin Yuen said she and her peer group of standard time backers still are not entirely confident in Trump’s pledge even though the president-elect's Truth Social post clearly spelled out his desire to end daylight savings time.
"I think we were all rather incredulous," Yuen told NBC News this week, days after Trump's post. "So yeah, we're elated. We're catching this wave that'll hopefully get more attention and point out the health benefits of adopting permanent standard time."
The manner in which Americans adjust their clocks twice a year is outlined in the Uniform Time Act of 1966, which set parameters for daylight savings time.
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America most recently fell back into standard time on Nov. 7 this year.
During standard time in fall and winter months, Americans enjoy about 9 to 11 hours of sunshine a day, generally starting between 6:30 a.m. and 7:30 a.m.
The nation springs forward to daylight savings next on March 9, 2025, ushering in spring and summer with 11 to 15 hours of daily sunshine that can often start between 5:30 a.m. and 6:30 a.m.
"There is a momentum to not have to change the clocks anymore," said Dr. Nathaniel Watson, a long-time advocate of permanent standard time and neurologist at the University of Washington Medicine Sleep Center.
"But there's this conflation of, 'Let's not change clocks and the only way to do that is go to permanent daylight savings time,' which is just not the case. It should just be standard time."
If America were to stay with standard time year-round, then sunshine during warm weather months would hit bedroom curtains at unaccustomed early hours, perhaps between 4:30 a.m. and 5:30 a.m.
And on the back end of summer days, the sun would set at earlier hours under standard time.
During summer months, baseball games that start at 7 p.m. can often absorb several innings of sunshine and twilight under daylight savings time. But those same summer night games, if played in standard time, might only yield an inning or two of fading sunshine before stadium lights take full effect.
The American Academy of Sleep Medicine formally endorsed year-round standard time in 2020 and the American Academy of Neurology joined on to that position in 2023.
The human body functions well for 16 waking hours a day with activities best planned around "solar noon" — when the sun is at its highest point in the sky, doctors backing universal standard time have said.
For most of standard time months, solar noon comes close to 12 p.m. on the wall clock. But during daylight savings months, that midpoint usually comes after 1 p.m.
And employees and students who have a 9-to-5 schedule will now get up an hour earlier than their bodies would want to in relation to solar noon.
"So you are forcing your body to get up at a time much earlier, you're basically tricking your body into saying, 'Get up an hour earlier for work and school,' which is why a lot of people hate mornings," said Dr. Karin Johnson, a neurologist and sleep expert at Baystate Medical Center in Springfield, Massachusetts.
"So if you were on daylight savings time (year-round), it would makes us hate those mornings even more."
For anyone concerned about the sun peeking through window shades just a few hours after stumbling home from their local bar, Johnson said that inconvenience is a small price to pay to be in better synch with circadian rhythm.
"Do we need 3 a.m. or 4 a.m. sunrises? No, none of us would like that," she said. "But you can put your face down and sleep through that. What we do need is for the sun to be in alignment with our bodies (under standard time)."
Trump's announcement was also surprising because it appears to conflict with popular sentiment and leaders of his own party.
The Senate two years ago overwhelmingly passed legislation to make daylight savings year-round though the bill stalled out from there.
Sen. Marco Rubio, R-Fla., Trump's pick to lead the State Department, was one of the bill's sponsors and has been a vocal supporter of daylight savings time.
The Insurance Institute for Highway Safety (IIHF), which is funded by insurance companies, has long advocated for year-round daylight saving time.
The group has said lives are saved when there's better visibility in afterwork and early evening driving hours.
"We know there’s a strong relationship between increased darkness and fatal crashes, especially when it comes to pedestrian and bicyclists," IIHF spokesperson Joseph Young said in a statement this week.
"Leaving daylight saving time behind would result in earlier sunsets during the summer months, which would very likely result in more fatalities involving these road users."
Should America ever flip the switch to turn off daylight savings time, widespread infrastructure upgrades would be necessary, according to the IIHF.
"If we do see daylight saving time come to an end, communities will need to think even harder about how to improve safety for those on foot," Young said. "Better lighting and infrastructure, lower vehicle speeds, and other changes that are already badly needed will become even more crucial."
Some business interests have also advocated for daylight savings time, believing it could lead to more afterwork commerce if it's not too dark.
A representative for Rubio could not be immediately reached for comment on Monday and a spokesperson for the National Retail Federation said her group has no formal position on daylight savings time.
What little polling on daylight savings vs. standard has been conducted over the years seems to slightly favor daylight savings.
YouGov posed the question in March 2023 and 50% of respondents said they would support permanent daylight savings time, while only 31% said they'd want year-round standard time.
"The marketing department of daylight savings time, which of course is highly connected with industries, did a much better job than we have," said Dr. Yuen from UCSF.
"We naturally have more sunlight (in daylight savings months), whether we had daylight saving time or not, we just have longer days. And I think that we need to do a better marketing job the other way around and remind people of sitting in the dark at school in winter."
The U.S. briefly adopted year-round daylight in 1974-75, in hopes of pushing more daylight into later hours and cutting energy use during the OPEC oil embargo. But using daylight savings time in winter was wildly unpopular, with children hiking to school in darkness, and it was quickly ended.
Dr. Johnson said she’s convinced poll respondents, who oppose permanent standard time, are conflating daylight savings with the good times of spring break and summer vacations — and forgetting about the rejection of year-round daylight savings time in 1974.
"There are huge (emotional) connections between summer and daylight savings time," Johnson said. "And yes, we like it when it's warm and the days are longer. But we've tried permanent daylight savings before, the last in 1974, and it didn't work."
U.S. Sen. Tom Cotton, R-Ark., invoked the bad memories of 1974 and said he’d be willing to help Trump push for year-round standard time.
“Congress once made Daylight Saving Time permanent. It was so unpopular that Congress repealed it less than a year later,” he said in a statement. “The only sensible and durable way to stop the biannual time change is to make Standard Time permanent.”
The biggest response in that 2003 YouGov poll appeared to come from people who don't want to change their clocks in either direction, as 62% respondents said they simply wanted the elimination of either standard or daylight savings time while 31% said they were OK with the status quo of both.
NBC News' Alexandra Marquez and Helen Kwong contributed.
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