Feeling a little groggy this morning? You are not alone.
Americans sleep 40 minutes less on the night of “springing forward” and the transition to Daylight Saving Time (DST). If you are feeling tired this morning please do not operate heavy machinery, and please do not drive.
A recent study by Austin Smith, an economics professor at Miami University’s Farmer School of Business in Miami, Ohio, found fatal car crashes increased anywhere from 5 percent to 6.5 percent after clocks were reset, and that this increased risk continues for six days. This amounts to an additional 30 deaths annually from changing our clocks.
If you lost a full hour of sleep last night, this increases the probability you will involved in a sleep deprived crash by 46 percent. There is no corresponding decrease in accidents in the fall when we “fall back.”
Smith argues the increased risk of a fatal accident is not due to the reallocation of ambient light from the morning to the evening, as that just reallocates crashes to other times of the day. It is actually the deprivation of just 40 minutes of sleep causing loss of concentration and increased accidents.
Workers in risky professions, such as mining, are more likely to be involved in accidents on the Monday following the time change. Also, many office workers are less productive on the Monday, opting to do things such as surf the web instead of work. Overall, these costs could amount to over $700 million annually.
DST was introduced in the United States as a wartime measure to save energy. Interestingly, only 1.5 billion people (about 20 percent of the world population) practice DST.
The U.S. transition dates were last changed as part of the Energy Policy Act of 2005. Ironically, economic research finds little evidence that changing the clocks saves energy! Evidence from Australia found that reduced energy demand in the lighter evening is offset by increased demand in the darker morning. Some counties in Indiana did not practice DST until 2006. Although economists found this change did reduce lighting use, it was more than offset by increased heating and cooling.
The lighter evenings may have positive benefits, however. Recent research has found DST is associated with lower crime and more exercise. But it is not obvious whether these benefits of DST outweigh the costs to society at large.
Nevertheless, they are significant, given the seemingly insignificant time change we have become used to making.
Simon Medcalfe is an associate finance professor and the Cree Walker Chair at Augusta University’s Hull College of Business.