New research sheds negative light on Daylight Saving Time

By Bryan Hay 

Springing forward to Daylight Saving Time (DST) on Sunday (March 9) comes with the reward of more daylight in the evening. But it will cost us with loss of sleep, dark mornings, a disruption in our natural circadian rhythm, a decline in productivity, and potential damage to mental health.

According to a recently published paper in the American Journal of Health Economics by Susan Averett, Charles A. Dana Professor of Economics, and her longtime research colleagues, Muzhe Yang, MacFarlane professor of economics at Lehigh University, and Laura Argys, professor of economics at University of Colorado at Denver, there’s roughly a 6% increase in the incidence of depression among people living on the eastern side of time zone borders where the sun sets later.

Susan Averett, Charles A. Dana Professor of Economics

“We had done papers on noise pollution and light pollution, and asked ourselves what we wanted to write about next,” Averett says. “We started to think about Daylight Saving Time and the link between daylight and mental health.”

In an op-ed sent to major media outlets across the country, Averett and her colleagues are advocating for a permanent change to Standard Time, as followed by Arizona and Hawaii, and to abandon DST, which they conclude causes a misalignment between daily schedules and the natural rhythm of the sun.

Over the course of the multi-year study, which used data from the Centers for Disease Control and Prevention, the trio exploited naturally occurring variations in solar time alignment created by the current configuration of U.S. time zones. They compared mental health outcomes for individuals living near time-zone borders—specifically contrasting those on the east side, who end up with more evening sunlight, with those on the west side.

Those on the east side of a time-zone border experience a greater mismatch between solar time and clock time and they found that this leads to higher levels of depression and reduced sleep. This circadian misalignment is made worse by the artificially contrived DST.

The human body is designed to align with the pattern of the sun and altering that natural balance has negative implications on our mental health and sleep quality, Averett says.

“In the paper, we talk about the costs of mental health, including lost work days, so it feeds into the economy in ways that you might not see at first glance,” she notes.

“When you make the switch and spring forward, you lose sleep and don’t feel like yourself for a couple days, like the feeling of being jet lagged, until you get used to it,” Averett  adds. “Right now, when the mornings are light, it’s really nice. It helps you get out of bed. Going back to the darker mornings makes it harder to get your day going, especially for high school kids who start their days early. It probably had impacts on my own kids when they were that age.”

Averett plans to reference this research in her econometrics class (ECON 253), in a discussion about what makes an interesting research project and what topics might inform and influence policymakers.

“One of the important things with economics research, and certainly with this one, is needing to know the actual cause,” she says. “In this case, it’s the time zone difference and not something else that’s causing these effects on our health.”

After years researching the implications of chronic circadian misalignment for our mental health and overall well-being, Averett says she’ll have a lot to ponder when she adjusts her clocks this weekend.

“I think what will go through my mind is, wow, it’s dark in the morning,” she laughs. “I think I’ll be watching myself to see if I notice any signs of mental distress or anything that throws me off. I’ll be curious to see if I become even more convinced standard time is the way to go.”