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March 22, 2022

Is permanent daylight saving time the best for our health?

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    The Senate last week unanimously passed the Sunshine Protection Act, which would make daylight saving time (DST) permanent—however, health experts have pushed back against the bill, arguing that permanent standard time is closer to people's natural circadian rhythms.

    Slide deck: Sleep services market trends

    The Senate makes a move towards permanent DST

    The Senate last week approved Sen. Marco Rubio's (R-Fla.) Sunshine Protection Act by unanimous consent. If enacted, the bill would make DST permanent year-round, although the House and President Joe Biden both must approve the bill before it can become law.

    A permanent move to DST would likely be supported by most Americans. An Economist/YouGov poll from last fall found that 63% of U.S. adults said they wanted to eliminate the current biannual time changes, and that more people supported implementing DST permanently over standard time.

    In addition, at least 18 states over the last four years have passed laws to permanently switch to DST, although federal law must be changed first to allow these state laws to be implemented.

    According to health experts, having a permanent time year-round would likely be beneficial to people's health. Switching the clocks twice a year often leads to sleep disruptions, which can impair health in several ways, leading to inattention, difficulty monitoring behavior, and decreased motor skills.

    The change to DST in the spring is particularly disruptive and has been associated with increased health risks and consequences. For example, multiple studies have found that the spring DST change is associated with an increased risk of heart attack and stroke. In addition, there is also evidence that fatal car accidents increase following a DST time change.

    However, there is currently no clear timeline for the bill. Rep. Frank Pallone Jr. (D-N.J.), who chairs the House Energy and Commerce Committee, said that "[i]t could be weeks—or it could be months" before the DST bill is scheduled for a vote in the House.

    America's previous attempt at permanent DST

    The Sunshine Protection Act is not the country's first attempt at moving to DST permanently. According to the Washington Post, the United States previously enacted permanent DST in 1973 as part of a two-year national trial. At the time, the country was in the middle of an energy crisis, and lawmakers believed more sunlight in the evening would help reduce Americans' energy consumption.

    However, this move toward permanent DST ended before the two-year trial was completed. During this time, many Americans were unhappy about going to work and school in the dark due to the later sunrises, and there were reports of increased traffic accidents in the darker mornings. In addition, there was little evidence that the change substantially reduced energy consumption as intended.

    "We have experimented with daylight saving time through one dark winter—and one winter is enough," said former Sen. Dick Clark (D-Iowa) in August 1974. A week later, the House voted 383-16 to repeal permanent DST, and the Senate agreed in a voice vote later in September 1974. President Gerald Ford quickly signed the repeal into law after that.

    Health experts urge permanent standard time instead

    Although health experts generally agree that a permanent year-round time would be more beneficial for people, some believe permanent standard time would be a better choice than permanent DST. According to The Atlantic, standard time is more aligned with the path of the sun, which is closely linked to natural human circadian rhythms.

    "Permanent standard time is better aligned to human circadian biology because the natural, daily cycle of light and darkness is a powerful timing cue that synchronizes with your internal body clock," said American Academy of Sleep Medicine's (AASM) spokesperson Shalini Paruthi of St. Louis University School of Medicine.

    "Daylight saving time increases morning exposure to darkness and evening exposure to sunlight, therefore disrupting the timing of our bodies' circadian rhythm, causing negative impacts on health and safety," Paruthi added.

    "Our internal clock is not connected to the clock on the wall. It's connected to the sun clock, because that's how it's been for millennia," said M. Adeel Rishi, a pulmonology, sleep medicine, and critical care specialist and vice chair of the AASM's public safety committee. "Regardless of what happens on the clock on the wall, it does not change the relationship between our internal clocks and the sun clock."

    Permanent DST, which would increase morning exposure to darkness and evening exposure to sunlight, may also negatively impact people's health. According to a 2017 study, people living in the western edges of time zones, which experience later sunrises and sunsets than the eastern edges, had an increased risk of several health issues, such as diabetes, sleep disorders, mental health conditions, and certain cancers.

    In addition, teenagers, who already have delayed circadian rhythms, as well as essential workers, are most likely to be disproportionately affected by a permanent DST time change since they would have to go to school and work in the dark, particularly during the winter.

    Overall, Karin Johnson, medical director of Baystate Health's regional sleep program and a board member of the nonprofit Save Standard Time, said the potential health impacts of permanent DST are not worth the slightly later sunsets in the winter.

    "The days are just so short, you actually aren't getting any meaningful light at the end of the day, and you're losing so much meaningful light that's even more important at the beginning of the day," she said. (Turgeon/Wright, The Atlantic, 3/18; Diamond, Washington Post, 3/19; Lotan/Fatima, Boston Globe, 3/16; Davis, NPR, 3/19; George, MedPage Today, 3/17)

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