March 6, 2020

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

Daily Briefing
    Editor's note: This popular story from the Daily Briefing's archives was republished on March 15, 2021.

    Every year, Americans spring forward into daylight saving time. But research shows the practice is unpopular—and potentially harmful—and now some health experts are calling for daylight saving time to be abolished.

    Cheat sheets: Evidence-based medicine 101

    The unpopular—and potentially unhealthy—time change

    Most Americans live in places that observe daylight saving time, meaning they set their clocks forward in the spring and back in the fall. Perhaps not surprisingly, a 2019 survey by the Associated Press and NORC Center for Public Affairs Research found just 28% of respondents were content switching their clocks back and forward in the fall and spring.

    There's also growing evidence that daylight saving time can negatively affect our health. Studies have found increased rates of ED visits and an increased risk of atrial fibrillation, depression, and suicide following daylight saving time.

    In addition, daylight saving time has been associated with an increased risk of heart attack and stroke, according to multiple studies. For example, one 2014 study found the risk of having a heart attack the Monday after a spring forward was about 25% higher than other Mondays.

    Muhammad Adeel Rishi, a pulmonologist and sleep physician at Mayo Clinic Health System, said, "It's a preventable cause of cardiac injury."

    There's also evidence that fatal car accidents increase following daylight saving time. A study published in Current Biology found that the risk of getting into a fatal car accident increased by 6% the week following a spring forward. The researchers did not observe a similar increase during the fall shift back to standard time.

    Celine Vetter, director of the Circadian and Sleep Epidemiology Lab at the University of Colorado Boulder who was senior author on the study, said although 6% is a small increase, daylight saving time affects "many, many individuals so we still think it's something that has quite a public health impact."

    Some health experts want to put daylight saving time to rest

    According to the Wall Street Journal, setting the clock forward forces a change on our "internal circadian clocks," which govern how our body runs, "from hormone levels to blood pressure."

    Till Roenneberg, president of the World Federation of Societies for Chronobiology, explained, "Most of our physiology is governed by a circadian clock. This body clock synchronizes to the sun time."

    For instance, if you travel to a different time zone, your circadian clock will adjust to a new cycle of darkness and light within a few days. However, with daylight saving time, "the dark-light cycle doesn't change but the time does," according to the Journal.

    As a result, there's a difference between your biological clock and social clock, resulting in what researchers call "social jet lag," according to Roseneberg.

    Roenneberg is among many health experts who want to see daylight saving time abolished, and last year was the lead author on a paper that argued in favor permanently moving the country to standard time. According to Roenneberg, a permanent standard time would be closer to the sun's natural time, which would mitigate social jet lag.

    Separately, Beth Ann Malow, a professor of neurology at Vanderbilt University Medical Center, argued in a JAMA Neurology opinion piece that the move back and forth during daylight saving time was unnecessary and harmful to the brain. "Going back and forth is ridiculous and disruptive, it makes no sense," she told the Journal.

    The movement to end the time changes is gaining traction in some states, according to the Journal. Nine states in the past three years have passed legislation to remain on daylight saving time all year, and more are considering similar measures to end it permanently, the Journal reports. However, states cannot end daylight saving time without congressional approval. Arizona is currently the only U.S. state that has federal approval to not observe daylight saving time.

    How to reduce health risks during daylight saving

    While daylight saving is still in effect, experts say you can mitigate the risks of entering daylight saving time. For instance, Robert Oexman, director of The Sleep to Live Institute, said individuals should try to expose themselves to as much light as early in the day as possible and decrease their "light exposure about one hour before [their] bedtime" to help maintain a proper wake-sleep cycle.

    Separately, Andrew Krumerman, a professor of medicine at Montefiore Medical Center/Albert Einstein College of Medicine, said, "People really need to pay attention to healthy sleep habits especially around this period of time" (Reddy, Wall Street Journal, 3/4; Vaidya, Becker's Hospital Review, 3/4; Resnick, Vox, 3/9/19; Pierson/Berkrot, Reuters, 3/29/14; Tate, Newsmax, 3/9/18).

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