Spring Daylight Saving Sparks Increase In Deadly Car Accidents, Study Finds

BOULDER, Colo. — Each March, as we all “spring forward” for daylight saving time, it’s common to feel a bit more groggy than usual. While springtime daylight saving means some much needed extra daylight, it also means many A.M. work commuters lose an hour of precious sleep. Troublingly, a new study finds that the first workweek following daylight saving time is a dangerous time to be on the road.

During this period, fatal car accidents in the U.S. increase by 6%, adding up to roughly 28 additional deaths per year, according to researchers at the University of Colorado, Boulder. Moreover, the study also noted that the farther west an individual lives in his or her time zone, the more likely they are to be involved in a deadly crash that week. The research was performed

“Our study provides additional, rigorous evidence that the switch to daylight saving time in spring leads to negative health and safety impacts,” says senior author Celine Vetter, assistant professor of integrative physiology, in a release. “These effects on fatal traffic accidents are real, and these deaths can be prevented.”

These findings are especially interesting considering the fact that many states, such as Oregon, Washington, and California, are already toying with the idea of doing away with daylight saving time altogether. Additionally, recent scientific studies have observed a correlation between daylight saving time and increases in heart problems and workplace injuries in the days immediately following a switch.

This study was by far the most comprehensive research effort on the topic of daylight saving and subsequent car accident rates; a total of 732,835 U.S. accidents between 1996-2017 were analyzed. The results of the analysis were clear: the days following spring daylight saving saw a consistent rise in fatal car accidents each year.

Just in case there was any doubt that this observed spike was due to daylight saving time, the annual uptick even switched from April to March in 2007, which is when spring daylight saving time was officially moved to the second Sunday in March instead of April’s first Sunday.

“Prior to 2007, we saw the risk increase in April, and when daylight saving time moved to March, so did the risk increase,” Vetter says. “That gave us even more confidence that the risk increase we observe is indeed attributable to the daylight saving time switch, and not something else.”

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Besides just lack of sleep, losing an hour in the morning also means that millions of commuters are forced to drive to work in the dark. This is especially true in areas within the western edge of their time zones, such as Amarillo, Texas. In these areas, it’s estimated that locals are already getting an average of 19 minutes less of sleep per night. This is due to the fact that the sun rises and sets later in these towns, but employees, of course, still have to arrive at work the same time as everyone else.

In these western areas, accident rates following spring daylight saving actually increased over 8%.

“They already tend to be more misaligned and sleep-deprived, and when you transition to daylight saving time it makes things worse,” comments first author Josef Fritz, a postdoctoral researcher in the Department of Integrative Physiology.

Across all U.S. regions, the majority of fatal accidents during this period occur in the morning.

So, what about “fall back” daylight saving time in the autumn? The week following this time change also sees a noticeable spike in car accidents, but most occur in the evening, no doubt due to the fact that nighttime comes about much earlier in the day.

Across all of the data used in the study, researchers say that 627 people have died from car accidents linked to springtime daylight saving.

“Our results support the theory that abolishing time changes completely would improve public health,” Vetter concludes. “But where do we head from here? Do we go to permanent standard time or permanent daylight saving time?”

The study is published in Current Biology.

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