Fatal Car Crashes Rise With Spring Clock Reset

Losing an hour’s sleep at the spring change to daylight saving time is at best inconvenient. Now new research suggests that it may be dangerous.

A study in Current Biology reports that the risk of having a fatal traffic accident increases significantly in the week following the spring clock reset.

Researchers used a federal government registry of 732,835 fatal motor vehicle accidents from 1996 to 2017. They found that there were 6 percent more fatal accidents in the week following the Sunday clock change than in the weeks before and after.

The increase averaged 9 percent in the hours before noon, which the investigators suggest may be connected to fatigue combined with the darker morning hours of the first week of daylight saving time. The only time of day that showed no effect was 4 p.m. to 8 p.m.

The sun rises later as you head west, and the researchers found that in the western third of each time zone, the number of fatal accidents increased by 8 percent, but by only 4 percent in the eastern third.

“There is strong evidence for something real going on” when we set the clocks ahead, said the senior author, Céline Vetter, an assistant professor of integrative physiology at the University of Colorado, “and there are no real benefits in daylight saving time for economics or energy saving. Let’s get rid of the switch to daylight saving time.”