Woman adjusting a clock after daylight savings time ends

Permanent daylight saving time promises brighter afternoons, but a new study suggests the tradeoff could be much darker mornings for American children. Researchers estimate that adopting year-round daylight saving time would add more than 2 billion school commutes before sunrise each year compared with the current system, potentially exposing students to greater traffic danger and less morning light.

The analysis, published in Current Biology, examined school schedules and sunrise data across 14 states before extending the results nationwide. In those states alone, permanent daylight saving time would create roughly 356 million additional pre-sunrise school travel events annually. Washington would see nearly 35 million more dark commutes, while the average high school student’s number of trips in darkness would rise from about 33.5 to 72.6 per year.

The safety concern is more than theoretical. Reviewing fatal motor-vehicle crashes recorded across the United States from 2015 through 2024, the researchers found that morning crashes occurring before sunrise had 77 percent higher odds of involving a pedestrian than crashes after sunrise. For pedestrians ages 5 to 18, the odds were more than twice as high. The study identifies an association rather than predicting a precise number of additional deaths, but the pattern is especially relevant to children walking, biking, or waiting for buses in winter darkness.

The biological clock is another part of the debate. Keeping daylight saving time all year would leave winter sunrises an hour later without changing school bell schedules, effectively moving the school day earlier relative to the sun. University of Washington biologist Horacio de la Iglesia, one of the study’s senior authors, has argued that the arrangement could interfere with children’s sleep timing while also putting more students on dark roads and at bus stops.

The findings arrive as Congress considers the Sunshine Protection Act of 2025, which would make daylight saving time the nation’s permanent clock standard. The House passed the measure 308–117 in July 2026, but it was then sent to the Senate Commerce, Science, and Transportation Committee, where it has stalled. That means the United States is still operating under the familiar seasonal schedule, including the autumn return to standard time.

For supporters, permanent daylight saving time would preserve later sunsets and eliminate the twice-yearly clock change. The new research reframes the choice around who pays for that extra evening light: during winter, children would face the earliest part of their school day under darker skies. Unless school start times, transportation schedules, or local safety measures change with the clocks, the researchers’ numbers suggest that “more daylight” would not mean more daylight where many students need it most.