“Beware the ides of March” was the soothsayer’s warning to Julius Caesar in Shakespeare’s play about the Roman Emperor. These days, the phrase has taken on the ominous meaning that something bad is about to occur on or around March 15.
Now, two researchers from Michigan State University have conducted a research project that could well contain the warning “Beware of the days after the change to Daylight Savings Time,” the second Sunday in March when an hour of sleep is lost as clocks jump ahead.
Using U.S. Department of Labor and Mine Safety and Health Administration data, Christopher Barnes and David Wagner, both doctoral candidates studying industrial and organizational psychology, found that the number of workplace accidents spikes after Daylight Savings Time changes every March.
On the other hand, they found no significant increase in workplace accidents or sleep loss when the clocks were set back an hour in November.
In two separate studies, they found that the March switch to Daylight Savings Time resulted in 40 minutes less sleep for American workers, a 5.7 percent increase in workplace injuries and nearly 68 percent more work days lost to injuries.
The research will be reported in the September issue of the Journal of Applied Psychology.
But can losing one hour of sleep really make a difference?
“Yes,” said Barnes, “it can. Especially for those engaged in jobs requiring a high level of attention to detail. Studies have shown that lost sleep causes attention levels to drop off.”
That’s why some industries, like trucking and airlines, have regulations setting limits on the consecutive hours that truckers can drive or crews fly without taking a break.
Barnes and Wagner noted that some researchers claim the one-hour clock adjustment does not, and could not, impact accident rates in organizations. “We contend that the springtime change is associated with an increase in the number and severity of workplace accidents,” they said.
There is other research available that tends to support Barnes and Wagner. A University of British Columbia study, using data from the Canadian Ministry of Transport, found that when Canada went into daylight savings time, there was an 8 percent increase risk of accidents on the Monday after the changeover. A similar study, using information from the U. S. National Highway Traffic Safety Administration, cited sleep deprivation as the most likely cause of a 17 percent increase in accidents on the Monday following the time change.
Barnes pointed out that is not uncommon for people to complain how tired they are when they lose sleep. Many people adjust to a pace where events recur regularly and they can be adversely affected when that schedule is disrupted. An obvious example is jet lag, which occurs when people travel across several time zones.
“Their internal clocks need some recovery time for these kind of disruptions,” Wagner said.
Barnes noted that people assume the change to Daylight Savings is not going to greatly affect them. After all it’s only one hour. And if they do have an accident or make a mistake, they are not likely to attribute it to sleep loss.
While their study focused on physical accidents, Barnes and Wagner said a logical extension could be mistakes in the office or workplace, such as transposing figures on a spread-sheet or filling the wrong prescription in a pharmacy.
The researchers used figures from the American Time Use Survey conducted by the Bureau of Labor Statistics, which included more than 14,000 interviews. They also studied data from the Mine Safety and Health Administration. In analyzing those figures, it was clear that people lost an average of 40 minutes’ sleep following the change to Daylight Savings and there was a jump in workplace accidents following the time change, the researchers said.
They looked at all Mondays in a year and allowed for seasonal effects and other factors. For example, there is more likelihood of snow in Michigan and Minnesota in March than in other parts of the country and the bad weather may have been more of a contributing factor to accidents than the time change.
However, the results clearly show that sleep does have a profound effect upon human behavior and lack of sleep can have significant and serious results, they say.
So, when next March rolls around and clocks are turned forward an hour, organizations should be aware that Daylight Savings Time may save daylight, but not without some cost to organizations.
By the way, Caesar would have done well to heed the soothsayer’s warning. On the 15th of March his friends and colleagues assassinated him.
The Society for Industrial and Organizational Psychology (SIOP)
Michigan State University
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