Ready for the time change? Daylight saving time ends this Sunday, when most Americans will set their clocks back one hour.
Many people would prefer to stop changing time altogether; there is even legislation making daylight saving time permanent. But it could have serious consequences for children’s safety, a new study suggests.
The research, published Thursday in the scientific journal Current Biology, examines how permanent daylight saving time could affect children traveling to school. Scientists at the University of Washington looked at school start times at more than 16,000 schools across 14 states, representing about 8.6 million children.
To help understand the findings and how families should handle the upcoming time change, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and clinical associate professor at George Washington University. She previously served as Baltimore’s health commissioner and is the mother of two young children.
CNN: Can you explain what happens when daylight saving time ends on November 1? Why do we change the time twice a year?
Dr. Leana Wen: On Sunday at 2 a.m., the clocks will “go back” or go back one hour until 1 a.m. This means that sunrise and sunset will occur an hour earlier, according to our clocks. In practice, the result is that people will have more daylight in the morning, but it will get dark earlier in the evening.
Daylight saving time was adopted to shift daylight more toward evening during the warmer months. In the United States, the celebration currently begins on the second Sunday in March and ends on the first Sunday in November.
Semi-annual clock changes are controversial because they disrupt people’s sleep schedules and daily routines. The spring transition is particularly difficult because people lose an hour of sleep. The fall transition gives us an extra hour, but it can still disrupt sleep, especially for young children who have established bedtime and wake-up routines.
CNN: There have been proposals to make daylight saving time permanent. Why do some people support this change?
Magnifying glass: The main argument is that people would no longer have to change their time twice a year. Supporters also favor more evening daylight throughout the year. As a result, people who finish work or school in the late afternoon would benefit from more daylight for outdoor exercise and recreational activities. Additional daylight in the evening could benefit some businesses and perhaps reduce some traffic accidents.
The Sunshine Protection Act, passed by the U.S. House of Representatives in July, proposes to make daylight saving time permanent nationwide. If this law were passed, Americans would keep their clocks on daylight saving time throughout the winter. This would mean an extra hour of daylight in the evening, but sunrise would also occur an hour later during the winter months.
Not everyone supports this change. Some advocates of ending time changes favor permanent standard time, which would keep clocks on standard time year-round and stop the shift to daylight saving time.
CNN: What did this new study reveal about the potential risks for children going to school?
Magnifying glass: The team calculated how many school mornings children would have to leave the house before sunrise under three scenarios: permanent standard time, the current system of changing clocks twice a year, and permanent daylight saving time.
The study authors estimated that permanent daylight saving time would result in about 356 million additional school trips before sunrise each year in these 14 states, compared to the current system. When the researchers expanded their analysis nationally, they estimated more than 2 billion additional morning school trips in the dark per year.
The researchers then examined whether traveling in the dark could pose additional safety risks. The team analyzed fatal motor vehicle crashes nationwide from 2015 to 2024, focusing on more than 10,000 fatal crashes that occurred on school year mornings between 7 and 8:30 a.m.
Scientists found that crashes before sunrise were 77% more likely to involve a pedestrian than crashes after sunrise. When they focused specifically on children ages 5 to 18, the odds of pedestrian involvement were more than twice as high during dark mornings, suggesting that schoolchildren could face greater risks if daylight saving time became permanent.
The United States briefly adopted permanent daylight saving time during the 1974 energy crisis, but reversed course within months, in part because of concerns about children walking to school in the dark.
CNN: Why are children particularly vulnerable to road accidents on dark mornings?
Magnifying glass: Visibility is a major factor. Drivers have more difficulty seeing pedestrians in the dark, especially children who tend to be smaller and less visible. Children who cross streets to walk to school or the bus stop may be at higher risk.
Younger children also develop the ability to judge a vehicle’s speed and distance. They may be less predictable when crossing streets. Teenagers who drive to school also face risks related to limited driving experience.
Despite the importance of the findings, policymakers should consider that this study is not an experiment in which researchers change clock policies and measure subsequent accidents. Instead, they used existing school schedules, sunrise calculations and historical accident records to estimate potential effects. Additionally, the nationwide estimate was based on an assumed school start time of 8 a.m., which is not the case everywhere. In fact, many schools start later.
I think the results still identify a plausible security issue. Additionally, as the researchers noted, children from low-income families may be disproportionately affected, as some must travel early to participate in school breakfast programs and are more likely to rely on walking and public transportation.
CNN: What are the arguments for and against permanent daylight saving time? Is Permanent Standard Time a better alternative?
Permanent daylight saving time would provide more evening daylight, which many people appreciate. Some research also suggests it could reduce vehicle collisions with deer. On the other hand, permanent standard time would preserve more daylight in the morning, when children and commuters head to school and work.
Several medical organizations, including sleep medicine specialists, favor permanent standard time because it better aligns our schedules with our natural body clocks, called circadian rhythms. These internal clocks regulate sleep, alertness, and other physiological functions. Morning sunlight helps synchronize them and signals the brain that it’s time to wake up.
Of course, none of these proposals would actually “block out sunlight” and add more natural light to the day. The question for policymakers is when this daylight would occur and how best to balance the benefits of morning versus evening light.
CNN: In the meantime, we’re going to change times soon. How can parents and guardians prepare their children – and themselves – in the days leading up to the time change?
Magnifying glass: For people with younger children or who have struggled with time changes themselves in the past, I recommend making small adjustments several days before the transition.
Because the clocks go back, a child who normally goes to bed at 8 p.m. will feel ready to go to bed at 7 p.m. after the change. Parents can gradually shift bedtime by about 15 minutes each day for four days before November 1. Moving meals, bath time and other evening routines later can help strengthen the adjustment.
Try to maintain consistent wake-up times and expose children immediately to natural light in the morning. Outdoor activity in the morning and throughout the day also promotes healthy sleep. In the evening, keep a predictable wind-down routine and try to avoid screen time before bed.
Adults can use similar strategies. Some people may feel sleepy earlier in the evening or wake up earlier than expected. Others may experience an attack in the afternoon because it gets dark earlier. I would recommend taking a walk outside during the day, exercising regularly, and avoiding caffeine late in the day.
Families should also prepare for earlier sunsets. Children who walk or bike home from school or participate in afternoon activities may find themselves in the dark sooner than before. Children should wear reflective clothing, use lights on bicycles, use marked crossings and, ideally, travel with an adult or group of friends to improve visibility and safety.
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