Daylight-Saving Time: Do Longer Days Mean More Accidents? Or Less?

Daylight-saving time (DST) is a bi-annual event that everyone loves to hate, especially the annual “spring forward”. Losing an hour of sleep is why most people detest springing forward, but there are much more serious reasons why DST is troublesome for Americans.

According to research, DST is linked to an increase in fatal car accidents, heart attacks and strokes. Consider the following:

  • Researchers estimate that drivers who are drowsy after losing an hour of sleep are responsible for taking the lives of 30 people between 2002 and 2011.
  • In 2004, researchers estimated that keeping DST all year long could save as many as 366 lives in auto accident fatalities.

Based on these statistics, it certainly seems like there is more to DST than meets the eye.

Does DST Cause a Spike in Auto Accidents?

It’s one thing to suggest that DST causes a spike in auto accidents, but it is another thing for research to prove it. In 2014, the University of Colorado Boulder showed a clear spike in fatal auto accidents in the six days after DST. In the six days following the DST spring forward, there was a 6.3 percent increase in fatal auto accidents.

In 1999, Johns Hopkins University and Stanford University studied 21 years of auto accident data and found a “small, but significant” increase in auto accident fatalities on the Monday after spring DST. The study estimated an average of 78.2 deadly accidents on a typical day, and 83.5 on that Monday.

Canada has also published research showing an increase in auto accidents following DST. In 2014, Manitoba Public Insurance reported a 20 percent increase in auto accidents on the Monday after springing forward. The spike is attributed to changes in ambient light and sleep deprivation among drivers.

Would Year-Round DST Reduce Auto Accidents?

The answer to this question appears to be “maybe”. Rutgers University professors have concluded that year-round DST could result in 171 fewer pedestrian fatalities per year, and 195 vehicle occupant fatalities per year.