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November 5, 2021

Why daylight saving time may be bad for your health

Daily Briefing
    Editor's note: This popular story from the Daily Briefing's archives was republished on Nov. 4, 2022.

    On Sunday, clocks will "fall back" in most of the country to mark the end of daylight saving time. But research shows that clock-switching is unpopular and may have adverse health consequences—leading some public health experts to argue for abolishing daylight saving time.

    Is it time to abolish daylight saving time? These experts say yes.

    What evidence suggests about the health effects of daylight saving time

    Most Americans live in places that observe daylight saving time, meaning they set their clocks forward in the spring and back in the fall. But studies show seven in 10 Americans would prefer not to switch back and forth each year, ABC 11 reports—and the American Academy of Sleep Medicine in 2020 endorsed switching to a year-round standard time.

    There's also growing evidence that daylight saving time can negatively affect human health. Multiple studies have found increased rates of ED visits and an increased risk of atrial fibrillationdepression, and suicide following shifts related to daylight saving time.

    In 2020, a National Institutes of Health (NIH) study found that roughly 150,000 Americans experienced physical health issues as a result of daylight saving time changes, including strokes, heart attacks, mood changes, and accidents. And in a 2015 study published in Sleep Medicine, researchers in Finland found that the overall risk of having a stroke was 8% higher in the two days following a time change for daylight saving from 2004 to 2013; that risk was 20% higher for people over the age of 65 and 25% higher for people with cancer.

    Some experts argue daylight saving time should end   

    Experts believe the negative health effects that accompany daylight saving time are caused by a mismatch between the body's "biological clock," or circadian rhythm, which guides when people feel inclined to sleep or wake up, and the "social clock," which governs work or school schedules.

    The resulting disruptions in sleep can impair health in many ways. For instance, experts have linked getting a good night's sleep with improved cognitive function and decision-making abilities, increased creativity, and more successfully regulated emotions, while a lack of sleep has been linked to inattention, poor focus, difficulty monitoring behavior, and decreased motor skills.

    In addition, while sufficient sleep allows the body to heal and repair heart and blood vessels, decreased sleep has been linked to an increased risk of heart disease, kidney disease, high blood pressure, diabetes, obesity, and stroke.

    "[Sleep is] one of the pillars of good health," Bhanu Kolla, a consultant for the center for sleep medicine at the Mayo Clinic, said.

    Separately, citing the link between poor sleep and inattention and poor focus, Judith Owens, co-director of the pediatric sleep program at Boston Children's Hospital and professor at Harvard Medical School, explained that "[i]ndividuals who don't get enough sleep are more likely to take risks because they perceive less consequence." She added, "For example, a child in elementary school darts out into the road because they are more impulsive and less vigilant."

    Ultimately, "[s]leep impacts how healthy you feel and how happy you feel because of its influence on those hormones and the shared areas," said Melisa Moore, assistant professor of clinical psychiatry at the Children's Hospital of Philadelphia's division of pulmonary medicine and sleep center.

    And speaking of daylight saving in particular, Erin Flynn-Evans, a consultant to the American Academy of Sleep Medicine's public safety committee, added, "There's really no reason we should continue to do this back and forth. The negative health consequences and the negative effect on multivehicular crashes in the spring are just not worth it."

    How to stay healthy during daylight saving

    Experts said people can mitigate the risks of entering daylight saving time by slowly altering their sleep schedules in advance of the change to soften the "blow," ABC 11 reports.

    Jennifer Ashton, ABC News' chief medical correspondent, advised people to get extra sunlight, eat lightly over the course of the day, and minimize screen time to keep circadian rhythms in balance.

    She also suggested paying attention to mood changes. "This can really affect people, and I think it's important not to dismiss those changes," she said. (Rodriguez, USA Today, 11/1; ABC 11 /AP/CNNWire, 11/1; Yoo, Kare11 News, 11/2)

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