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.