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Another Reason to Hate Daylight Saving Time: Stroke Risk

Researchers say they’ve found a rise in brain-damaging blood clots right after the time switch.

Puwadol Jaturawutthichai/Shutterstock.com

Aside from feeling discombobulated, here’s another thing to worry about when Daylight Saving Time arrives March 13: brain-ravaging blood clots.

Researchers today released a preliminary study detailing their examination of a decade of hospital records in Finland, saying they’ve found a spike in patients with ischemic strokes after Daylight Saving. The rate of strokes jumped 8 percent in the two days after the time switch, compared with two weeks before and after, though following that brief period it settled back down to average.

They believe a disruption in the body’s natural cycle is behind the rise in strokes. Here’s more from a press release:

“Previous studies have shown that disruptions in a person’s circadian rhythm, also called an internal body clock, increase the risk of ischemic stroke, so we wanted to find out if daylight saving time was putting people at risk,” said study author Jori Ruuskanen, MD, PhD, of the University of Turku in Turku, Finland....

People with cancer were 25 percent more likely to have a stroke after daylight saving time than during another period. The risk was also higher for those over age 65, who were 20 percent more likely to have a stroke right after the transition.

Hospital deaths from stroke did not increase in the week after a daylight saving time transition.

The researchers will share more information when they present the final study in April at the American Academy of Neurology’s annual meeting in Vancouver.

Top image: Puwadol Jaturawutthichai/Shutterstock.com

About the Author

  • John Metcalfe
    John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.