SPOKANE, Wash.—Each spring, clocks in most of the United States leap forward an hour for summer daylight saving time, renewing debate over whether the switch should be abandoned in favor of a consistent year-round schedule.
The impacts of ending the annual time change, which takes place this year on March 9, could be complicated, especially in eastern Washington, says internationally recognized sleep scientist Hans Van Dongen, PhD, a WSU Elson S. Floyd College of Medicine professor and Sleep and Performance Research Center core faculty member. Our schedules relative to the sun impact not only health and well-being but also work performance and safety.
The hour of lost sleep from the spring time change is linked to temporary negative health impacts, including a rise in heart attacks and car accidents. People who are already sleep deprived are particularly vulnerable to the effects of losing an hour of rest, Van Dongen said.
“When you’re well rested, you have plenty of reserves to absorb that hour, and a couple of days later you don’t even notice the difference,” Van Dongen said. “It gets trickier when you’re already living on a sleep budget.”
After making the switch, however, residents of most areas enjoy more daylight on summer evenings. The tradeoff is evening exposure to light tends to disrupt circadian rhythms, leading to later bedtimes and less sleep as people wake up at the same time for rigid work and school schedules, according to the American Academy of Sleep Medicine.
“We ask people to be alert and be awake at times that our biology would not necessarily prefer, although there are large individual differences,” Van Dongen said.
Despite federal and Washington state proposals to move to daylight saving time permanently, many in the scientific community support permanent standard time for its alignment with human circadian biology.
We don’t know much about what the health and economic impacts of either proposal could be in the Pacific Northwest, Van Dongen notes. Evidence from the states that have moved to permanent standard time—Arizona and Hawaii—wouldn’t be as applicable to Washington, which is located farther from the equator and thus has different seasonal daylight and temperature shifts.
“If we choose either one of those, it will be a grand experiment,” Van Dongen said.
A third option is to stick with an annual time change, which Van Dongen supports. Historically, most cultures far from the equator gradually shifted their schedules with the changing seasons, typically rising an hour later in the winter, he said.
“Daylight saving time mimics that natural variation over the seasons, although that wasn’t why it was originally instituted,” Van Dongen said. “Making that one-hour shift suddenly can cause some problems, but we don’t actually know that holding the time constant would be a better compromise.”
Moving further away from that natural variation could cause more problems, including potentially increasing rates of seasonal affective disorder.
“Some researchers theorize that people who are susceptible to winter depression adapt to the seasons, but the world around them does not because we live by the clock and not by the sun,” Van Dongen said. “So, they get depressed in the winter because of that mismatch. We anticipate that if we hold time steady, more people could be susceptible to that depression.”
Eliminating the time change could also disproportionately impact people who live on the edges of time zones, including those in eastern Washington. Located on the eastern edge of the Pacific Time Zone, the sun sets earlier in the day here than on the west side.
Making daylight saving time permanent would preserve more typical evening sunlight in eastern Washington during the summers but would mean more dark mornings during the rest of the year. Permanent standard time would preserve more morning light, believed to be essential for healthy circadian rhythms, but would largely eliminate long evenings in the region.
Van Dongen argues that the ideal solution is to build flexibility into work and school schedules whenever possible. This can accomplish the same seasonal shift as daylight saving time with more flexibility to allow for differences in individual biology, such as differences between night owls and morning larks.
“If you have flexibility in how you spend your time, then who cares exactly what time it is on your clock?” he said. “But we also have to realize that not everybody has that flexibility. It’s always going to be a nuanced debate.”
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Stephanie Engle, WSU Elson S. Floyd College of Medicine Communications and Marketing, 509-368-6937, stephanie.engle@wsu.edu