(CNN) -- Daylight saving time ended last Sunday, with many countries turning back the clocks 60 minutes.
While many support eliminating the time change, legislation has been proposed to maintain daylight saving time year-round. But a new study warns that this step may threaten children's safety.
The study, published Thursday in the journal "Current Biology," examined the impact of adopting daylight saving time throughout the year on children's transportation to school. Researchers from the University of Washington analyzed start times in more than 16,000 schools in 14 states, including about 8.6 million children.
To understand the study results and prepare for the upcoming clock change, CNN spoke with Dr. Leana Wen, an emergency physician and assistant professor at George Washington University, former Baltimore health commissioner and mother of two.
CNN: What happens when daylight saving time ends on November 1? Why do we change clocks twice a year?
Wayne: At 2 a.m. Sunday, the clocks turn back 60 minutes, to 1 a.m. Thus, the sun rises and sets an hour earlier, so daylight increases in the morning, while darkness falls early in the evening.
Daylight Saving Time aims to extend the hours of evening daylight during the warm months, and begins on the second Sunday in March and ends on the first Sunday in November.
Changing the time twice a year raises controversy because of its impact on sleep and daily routine. The transition to daylight saving time in the spring is more difficult, as people lose an hour of sleep, while they gain an hour in the fall. But change can also disrupt sleep, especially in young children who are used to consistent bedtime and wake-up schedules.
CNN: What potential risks did the study reveal to the safety of children while they go to school?
Wayne: The researchers compared the number of times children would leave their homes before sunrise per year, under three scenarios.
They estimated that the latter scenario would result in an additional 356 million trips to school before sunrise annually in the 14 states included in the study, and more than 2 billion trips when generalizing the estimate to the United States.
They also analyzed more than 10,000 fatal traffic accidents that occurred during the school year between 7 and 8:30 a.m., across the country between 2015 and 2024, to assess the risks of traveling in the dark.
The results showed that the probability of accidents involving pedestrians occurring before sunrise is 77% higher compared to the following period. Among children ages 5 to 18, they are more than twice as likely to be run over in the dark, indicating the dangers of year-round daylight saving time.
The United States had previously adopted year-round daylight saving time for a brief period during the 1974 energy crisis, but reversed the decision months later, partly due to concerns about children heading to school in the dark.
CNN: Why are children more vulnerable to traffic accidents in the dark morning?
Wayne: It is difficult for drivers to see pedestrians in the dark, especially children, due to their small size, which increases their risk of accidents while crossing the roads leading to school or bus stops.
Younger children also have difficulty judging the speed and distance of cars, and their behavior when crossing roads may be difficult to predict. As for teenagers who drive to school, their lack of experience increases their risk of accidents.
However, the study did not test the time change and measure its actual impact on accidents. Rather, it estimated the risks based on work start times, sunrise times, and previous accident records. Also, I assumed that school starts at 8 a.m. across the country, even though many schools start later.
Wen says the findings raise serious safety concerns, especially for children from low-income families, some of whom go early to school to participate in breakfast programs and rely more on walking and public transportation.
CNN: What are the arguments for and against adopting daylight saving time year-round? Is permanent winter time a better alternative?
Wayne: Permanent daylight saving time provides more daylight in the evening, which many people prefer, and may also reduce car-deer collisions. In contrast, permanent winter time allows more light in the morning, when children go to school and employees go to work.
Several medical organizations, including associations specialized in sleep medicine, support the adoption of winter time throughout the year because it is better compatible with the body’s biological clock, which regulates sleep, wakefulness, and other functions. Morning light helps regulate them and sends signals to the brain that it is time to wake up.
Neither option increases daylight hours, but rather changes the timing of daylight hours and the balance between the benefits of morning and evening light.
CNN: How can parents prepare for the upcoming time change and prepare for their children, while also considering its impact on them?
Wayne: Wayne advises parents, especially those who have young children or have had difficulty adjusting to the time change, to gradually adjust their bedtimes several days in advance.
When the clock is late, a child who is accustomed to sleeping at eight in the evening may feel sleepy at seven according to the new time. Therefore, it is recommended to delay his bedtime by 15 minutes daily during the four days prior to November 1, while adjusting the times of meals, bathing, and evening activities.
Wake up times should be fixed, children should be exposed to sunlight in the morning and encouraged to be active outdoors, while avoiding screens and following a quiet routine in the evening.
Adults can follow the same steps, along with walking during the day, exercising regularly, and avoiding caffeine late in the day, to alleviate early afternoon sleepiness or lethargy.
As darkness falls early, children returning from school on foot or bicycle, or participating in afternoon activities, are advised to wear reflective clothing, use bicycle lights, cross roads at designated areas, and travel with an adult or group of friends.
