Permanent Daylight Saving Time could lead to at least 2B more dark commutes to school for US children
University of Washington
video:
Horacio de la Iglesia, UW professor of biology, discusses how permanent Daylight Saving Time will affect commutes for school children.
view moreCredit: Sarah McQuate/University of Washington
The U.S. House of Representatives passed a bill this past summer that would make Daylight Saving Time (DST) permanent in the United States — meaning there would be no turning back the clocks each fall. Nineteen states, including Washington, have already preapproved this change. If the bill is ultimately signed into law, the change would go into effect in those states.
The bill is currently stalled in the U.S. Senate. School start times are a central issue because permanent DST would lead to darker mornings from November to March. This would mean darker commutes for everyone, but how much would it affect children going to school? University of Washington researchers did the math for 14 out of the 19 states that preapproved the change. Using school start times, enrollment data, and latitude and longitude measurements, the team calculated just how many days each child would be commuting to school in the dark and then added the trips together.
In Washington, there would be almost 35 million more trips to school in the dark under permanent DST compared to the current system of switching between DST and Standard Time twice a year. The other 13 states followed a similar trend, with Georgia having the highest deviation from the current system — 71 million more trips. When the researchers extrapolated these results for the rest of the country, it added at least 2 billion more dark commutes to school.
The team also analyzed traffic collision data from the U.S. and found that it was roughly twice as likely for a fatal crash involving a school-aged pedestrian to occur during dark mornings than after sunrise.
The researchers published these results Oct. 29 in Current Biology.
"It's called the 'Sunshine Protection Act' because you get an extra hour of light at the end of the day. But you will take that hour from the morning. You could call it the Sunshine Destruction Act," said senior author Horacio de la Iglesia, UW professor of biology. "These dark mornings will inequitably affect children who have to go to school at a certain time. It's a very tangible metric that anybody from any state or socioeconomic background can relate to. Nobody wants their kids to go to school in the dark."
Dark mornings affect everyone. Exposure to bright light in the morning helps set our circadian clock, which helps regulate many facets of our lives, such as our mood, sleep and appetite. Without that morning light, our bodies struggle to regulate these key functions.
"When we send kids to school in the dark, we are depriving them from an opportunity to get that morning daylight," said lead author Guadalupe Rodríguez Ferrante, a UW postdoctoral scholar in biology. "We were asking what's the cost for these children. We wanted actual numbers, a real number of kids based on the geographic location of each school."
The study revealed the areas that would be the hardest hit by the switch: communities on the western edge of their time zones, such as Forks, Washington, and communities with early school start times. For example, Mississippi and Alabama schools have an average start time of earlier than 8 a.m. and both balloon from about 2 million dark trips for each state under the current system to more than 20 million dark trips for each state under permanent DST.
"Some districts probably never experience a dark commute under the current system, and, if this passes, suddenly they will wake up to this new reality that their kids are going to school in the dark," Rodríguez Ferrante said. "Keep in mind that we used the actual start time listed for each school, and a lot of schools offer breakfast or other things before school, so the kids could be getting there even earlier."
After calculating real numbers for 14 states, the researchers estimated the total change in dark commutes if the whole country shifted to permanent DST. It adds up to about 2 billion more trips than under the current system.
"For the estimation, we assumed students would be leaving home around 8 a.m.," Rodríguez Ferrante said. "That's pretty late, so our calculation is likely an underestimation of the real number."
The researchers argue that permanent DST would also undo the benefits of having a delayed start time for high school students, which is intended to account for teenagers’ shifted circadian clock compared to kids and adults.
"I've heard the argument, 'If we're in permanent DST, we can just delay the school start time to address these issues,'" de la Iglesia said. "Well, if we do that, you will end up going to work later. And everything is going to get delayed. You will get out of work an hour later, and you will miss the opportunity to enjoy your evening light. And essentially, we're just going to be realigning everybody to solar time. That, by definition, is Standard Time."
Daniel Zhang, a high school student, and UW biology undergraduate students Nirekh Dasika, Alicia Nam, Jessie Lu, Navneet Tumber, Elena Kully-Rivera, Viridian Klei, Micaela E. Romero are also co-authors on this paper.
For more information, contact de la Iglesia at horaciod@uw.edu and Rodríguez Ferrante at guadarf@uw.edu.
Journal
Current Biology
Article Title
Over a Billion More Dark Morning School Commutes for K-12 Children under the Sunshine Protection Act
Article Publication Date
29-Oct-2026
The Sunshine Protection Act puts K–12 children at greater risk for fatal car crashes
In July 2026, the US House passed legislation to make daylight saving time (DST) permanent. But a new analysis of the consequences of the “Sunshine Protection Act,” reported in the Cell Press journal Current Biology on October 29, finds that this legislation would come with serious safety consequences for millions of schoolchildren across the US who would have to leave for school before sunrise, when fatal crashes with pedestrians are more likely, for much of the school year. Permanent DST would lead to more than 2 billion pre-sunrise commutes for children, and students who walk or take the bus to school would face an increased risk of early morning crashes.
“Permanent DST would move the school day earlier relative to the sun without changing a single bell schedule, putting millions of children on streets and at bus stops in the dark for weeks or months every year,” says Horacio de la Iglesia of the University of Washington, Seattle.
Much of the public debate around permanent DST has focused on the light available during the evening. But the researchers say that mornings are a critical time for schoolchildren, who would generally return home during light hours under any clock policy. The de la Iglesia lab has long studied the way school start times affect adolescent sleep, including the move in Seattle and many other school districts to later secondary school start times. When the US House passed the Sunshine Protection Act in July 2026, the team realized that no one had investigated how many children would be sent to school in the dark under the new policy.
“The US has tried this before,” says Guadalupe Rodríguez Ferrante, also at the University of Washington, Seattle. Year-round DST took effect in January 1974 and was abandoned that October, in part because of public concern over dark winter mornings and children traveling to school. “All of today’s students, and most of today’s parents, have never lived through a winter on DST, so experience with the current seasonal system does not tell us what permanent DST would be like.”
The researchers gathered school start times in 14 states with permanent DST along with local sunrise times. They counted the number of pre-sunrise commutes in each location and found that there would be about 356 million more pre-sunrise school commutes with the move to permanent DST. When they broadened their approach beyond these states to the entire US, they found that the Sunshine Protection Act would lead to more than 2 billion dark morning commutes for children. They also found that students in both northern and southern states would be impacted, and Georgia had the highest number of pre-sunrise school commutes of all states analyzed.
The team then analyzed fatal-crash records in the US over a decade and found greater odds of crashes involving pedestrians on dark mornings. Among fatal morning crashes, those involving pedestrians aged 5 to 18 were more likely when it was dark. The data suggest that permanent DST would lead to more children at an increased risk of early morning crashes, say the researchers.
“The burden of permanent DST is likely greatest for children who walk, wait for buses, or arrive early for school breakfast programs, which disproportionately serve lower-income families,” says Ferrante.
The US’s current system of shifting the clocks forward and back also doubles the number of dark school mornings compared with permanent standard time (ST). Permanent ST is not only safer for children going to school, the researchers say, it also keeps students’ solar, biological, and social clocks best aligned, according to the team’s past research.
“The name ‘Sunshine Protection Act’ is misleading,” says de la Iglesia. “No clock policy adds a single minute of daylight. It only changes when that daylight is available, and permanent DST moves an hour of light out of the morning, when children travel to school, and into the evening.”
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Current Biology, Rodríguez Ferrante et al., “Over a billion more dark-morning school commutes for K–12 children under the Sunshine Protection Act” https://www.cell.com/current-biology/fulltext/S0960-9822(26)01348-5
Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit: http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.
Journal
Current Biology
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
Over a Billion More Dark Morning School Commutes for K-12 Children under the Sunshine Protection Act
Article Publication Date
29-Oct-2026
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