As much of the world prepares to turn clocks back an hour this fall, new research from the University of Oregon finds the annual spring forward to daylight saving time affects worker productivity more than previously thought.

Rather than affecting workers for just a day or two, the adjustment to daylight saving time can affect worker productivity for up to two weeks, said Glen Waddell, a UO labor economist and co-author of a new research in the Journal of Economic Behavior and Organization. He collaborated on the paper with Andrew Dickinson, a doctoral student in economics in the UO’s College of Arts and Sciences.

The researchers did not identify a similar effect in the fall. They found that early-morning productivity picked up following the return to standard time.

Waddell and Dickinson looked at the daily work activity of 174,505 people who used GitHub around the transition to daylight saving time from 2013 to 2019. GitHub is a cloud-based version-control platform used by software developers, engineers and other collaborative programmers. It has 83 million users worldwide.

The publicly available GitHub records enabled the researchers to examine worker activity down to the second.

“When we look inside the day, hour by hour, we’re actually able to see patterns of workers getting off to a bumpy start in the early morning and trying to make up for their lost productivity throughout the rest of the afternoon, and this is happening for upwards of two weeks,” Waddell said.

Although GitHub users don’t represent all workers, they do provide valuable insights into how “losing” an hour in the transition to daylight saving time affected their productivity, he said. 

The researchers also looked at the effect on workers when they returned to standard time in the fall. 

“We actually see a picking up of productivity in those early morning hours, 8 a.m. to 10 a.m., with the extra sleep being the likely reason,” Waddell said. 

The paper’s findings have direct relevance for the 1.6 billion people in 75 countries who change to daylight saving time each spring and back to standard time each fall.

The research also comes at a time when United States lawmakers are considering abandoning the yearly time change. In 2021, the U.S. Senate unanimously passed the Sunshine Protection Act, which would end the return to standard time for the months of November to March.

“Our research findings could be interpreted as yet more reason to put this clock-switching experiment behind us,” Waddell said. “If we were fence-sitters before, maybe this is just another nudge toward the direction of doing away with this practice.”

Arizona and Hawaii already remain on standard time all year, and a growing number of countries, including China, Russia, Pakistan and Brazil, also have abandoned daylight saving time.

Introduced in 1916 and soon after adopted by many Western countries, daylight saving time was intended to save energy. However, consensus opinion today finds the energy savings to be negligible,  on the order of plus or minus 1 percent, according to the paper.

—By Sherri Buri McDonald, University Communications