A nationwide switch to permanent daylight saving time in the United States would produce at least two billion additional journeys to school before sunrise, according to research from the University of Washington.
The study was published on 29 October in the journal Current Biology and written up by ScienceDaily from material provided by the university.
Permanent daylight saving time would push sunrise an hour later during the winter months, leaving mornings darker from November through March. Although that would affect everyone travelling early in the day, the research team wanted to understand what it would mean specifically for children heading to school.
The team examined 14 of the 19 states that have already approved permanent daylight saving measures, combining school enrolment figures, individual school start times and geographic coordinates to determine how frequently students would need to travel before sunrise. They then compared the total with the current practice of changing the clocks twice a year.
In Washington state alone, permanent daylight saving time would produce nearly 35 million additional school commutes in darkness. Georgia showed the largest increase, at approximately 71 million. Extending the method nationwide produced the figure of at least two billion.
Mississippi and Alabama illustrate the scale. Schools in both states begin, on average, before 8am. Under the current clock system each state has approximately two million school trips in darkness; under permanent daylight saving time that would rise to more than 20 million trips per state.
The authors believe their national estimate is conservative, because to project it they assumed students would generally be leaving for school at around 8am. "For the estimation, we assumed students would be leaving home around 8 a.m.," said lead author Guadalupe Rodríguez Ferrante, a postdoctoral researcher in biology at the university. "That's pretty late, so our calculation is likely an underestimation of the real number."
Legislation to eliminate the annual return to standard time was approved by the US House of Representatives this past summer and remains stalled in the Senate, with school start times emerging as a major concern. Nineteen states have approved measures supporting the change, which would take effect in those states if the federal bill becomes law.
The researchers also point to the loss of morning daylight itself. Bright light early in the day helps synchronise the circadian clock, the internal timing system that influences sleep, mood and appetite. "When we send kids to school in the dark, we are depriving them from an opportunity to get that morning daylight," Rodríguez Ferrante said.
Senior author Horacio de la Iglesia, a professor of biology at the university, addressed the suggestion that schools could simply start later to compensate. "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," he said.
The two billion figure deserves a moment of attention, because of what it is a measurement of. It is not a count of darkness created. It is a count of darkness relocated.
The quantity of darkness available to the United States over a year is set by the rotation of the Earth and the tilt of its axis, and neither appears anywhere in the bill. The Sunshine Protection Act protects sunshine by moving an hour of it out of the morning and into the evening, where it is protected, and leaving the morning where the sunshine used to be.
Our analysts find the accounting sound and the title defensible. An hour of light at the end of the day is a real hour. It is simply the same hour, inspected at a more convenient moment, after a round trip of twelve hours during which nobody is required to look at it.
The Department of Unnecessary Research notes that the two billion journeys would be made in darkness already carried on the national books, and merely rescheduled. The clocks are the only item in the proposal that anyone has suggested amending.