Changing clocks can hurt work productivity for two weeks

(MARCH 6, 2025) Moving the clocks forward one hour in spring can hurt workers' productivity for up to two weeks — not just one or two days — according to a study from the University of Oregon.  

Economist Glen Waddell and student researcher Andrew Dickinson studied how the time change affects workers. Their research was published in the Journal of Economic Behavior and Organization. 

They looked at the daily work activity of more than 174,000 people who used GitHub from 2013 to 2019. GitHub is a website where software developers and engineers share and work on projects together. The site has 83 million users around the world.  

By looking at records from GitHub, the researchers could see exactly when workers were active, down to the second. They found that workers were slower in the mornings after the clocks changed. Workers tried to catch up later in the day, but the effect lasted up to two weeks.  

The researchers also studied what happens when clocks move back one hour in the fall. They saw that workers were more productive in the mornings, likely because they got extra sleep.  

Daylight saving time affects 1.6 billion people in 75 countries. Lawmakers in the U.S. are discussing whether to end the yearly time change. The Sunshine Protection Act, passed by the U.S. Senate in 2021, would make daylight saving time permanent.  

Waddell said the study gives more reasons to stop changing the clocks.  

Some places, like Arizona, Hawaii, China, and Brazil, have already stopped using daylight saving time. The practice started in 1916 to save energy, but experts now say the energy savings are very small — only about 1 percent.  

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In the U.S., only Arizona (outside the Navajo Nation) and Hawaii, along with five U.S. territories, including Puerto Rico, currently do not observe daylight saving time.