Time Is of the Essence: DST Up for Debate Again

Will Pass

March 25, 2021

Seasonal time change is now up for consideration in the U.S. Congress, prompting sleep medicine specialists to weigh in on the health impact of a major policy change.

As lawmakers in Washington propose an end to seasonal time changes by permanently establishing daylight saving time (DST), the American Academy of Sleep Medicine (AASM) is pushing for a Congressional hearing so scientists can present evidence in favor of converse legislation – to make standard time the new norm.

According to the AASM, seasonal time changes in either direction have been associated with a range of detrimental health effects; however, the switch from standard time to DST incurs more risk.

"Current evidence best supports the adoption of year-round standard time, which aligns best with human circadian biology and provides distinct benefits for public health and safety," the AASM noted in a 2020 position statement on DST.

The statement cites a number of studies that have reported associations between the switch to DST and acute, negative health outcomes, including higher rates of hospital admission, cardiovascular morbidity, atrial fibrillation, and stroke. The time shift has been associated with a spectrum of cellular, metabolic, and circadian derangements, from increased production of inflammatory markers, to higher blood pressure, and loss of sleep. These biological effects may have far-reaching consequences, including increased rates of fatal motor accidents in the days following the time change, and even increased volatility in the stock market, which may stem from cognitive deficits.

U.S. Senator Marco Rubio (R-Fla.) and others in the U.S. Congress have reintroduced the 2019 Sunshine Protection Act, legislation that would make DST permanent across the country. According to a statement on Sen. Rubio's website, "The bill reflects the Florida legislature's 2018 enactment of year-round DST; however, for Florida's change to apply, a change in the federal statute is required. Fifteen other states – Arkansas, Alabama, California, Delaware, Georgia, Idaho, Louisiana, Maine, Ohio, Oregon, South Carolina, Tennessee, Utah, Washington, and Wyoming – have passed similar laws, resolutions, or voter initiatives, and dozens more are looking. The legislation, if enacted, would apply to those states [that] currently participate in DST, which most states observe for eight months out of the year."

A Stitch in Time

"The sudden change in clock time disrupts sleep/wake patterns, decreasing total sleep time and sleep quality, leading to decrements in daytime cognition," said Kannan Ramar, MBBS, MD, president of the AASM and a sleep medicine specialist at Mayo Clinic, Rochester, Minn.

Dr Kannan Ramar

Emphasizing this point, Dr. Ramar noted a recent study that reported an 18% increase in "patient safety-related incidents associated with human error" among health care workers within a week of the spring time change.

"Irregular bedtimes and wake times disrupt the timing of our circadian rhythms, which can lead to symptoms of insomnia or long-term, excessive daytime sleepiness. Lack of sleep can lead to numerous adverse effects on our minds, including decreased cognitive function, trouble concentrating, and general moodiness," Dr. Ramar said.

He noted that these impacts may be more significant among certain individuals.

"The daylight saving time changes can be especially problematic for any populations that already experience chronic insufficient sleep or other sleep difficulties," Dr. Ramar said. "Populations at greatest risk include teenagers, who tend to experience chronic sleep restriction during the school week, and night shift workers, who often struggle to sleep well during daytime hours."

While fewer studies have evaluated the long-term effects of seasonal time changes, the AASM position statement cited evidence that "the body clock does not adjust to daylight saving time after several months," possibly because "daylight saving time is less well-aligned with intrinsic human circadian physiology, and it disrupts the natural seasonal adjustment of the human clock due to the effect of late-evening light on the circadian rhythm."

According to the AASM, permanent DST, as proposed by Sen. Rubio and colleagues, could "result in permanent phase delay, a condition that can also lead to a perpetual discrepancy between the innate biological clock and the extrinsic environmental clock, as well as chronic sleep loss due to early morning social demands that truncate the opportunity to sleep." This mismatch between sleep/wake cycles and social demands, known as "social jet lag," has been associated with chronic health risks, including metabolic syndrome, obesity, depression, and cardiovascular disease.

Cardiac Impacts of Seasonal Time Change

Muhammad Adeel Rishi, MD, a sleep specialist at Mayo Clinic, Eau Claire, Wis., and lead author of the AASM position statement, highlighted cardiovascular risks in a written statement for this article, noting increased rates of heart attack following the spring time change, and a higher risk of atrial fibrillation.

"Mayo Clinic has not taken a position on this issue," Dr. Rishi noted. Still, he advocated for permanent standard time as the author of the AASM position statement and vice chair of the AASM public safety committee.

Jay Chudow, MD, and Andrew K. Krumerman, MD, of Montefiore Medical Center, New York, lead author and principal author, respectively, of a recent study that reported increased rates of atrial fibrillation admissions after DST transitions, had the same stance.

"We support elimination of seasonal time changes from a health perspective," they wrote in a joint comment. "There is mounting evidence of a negative health impact with these seasonal time changes related to effects on sleep and circadian rhythm. Our work found the spring change was associated with more admissions for atrial fibrillation. This added to prior evidence of increased cardiovascular events related to these time changes. If physicians counsel patients on reducing risk factors for disease, shouldn't we do the same as a society?"

Pros and Cons

Not all sleep experts are convinced. Mary Jo Farmer, MD, PhD, FCCP, a sleep specialist and director of pulmonary hypertension services at Baystate Medical Center, and assistant professor of medicine at the University of Massachusetts, Springfield, considers perspectives from both sides of the issue.

"Daylight saving time promotes active lifestyles as people engage in more outdoor activities after work and school, [and] daylight saving time produces economic and safety benefits to society as retail revenues are higher and crimes are lower," Dr. Farmer said. "Alternatively, moving the clocks forward is a cost burden to the U.S. economy when health issues, decreased productivity, and workplace injuries are considered."

If one time system is permanently established, Dr. Farmer anticipates divided opinions from patients with sleep issues, regardless of which system is chosen.

"I can tell you, I have a cohort of sleep patients who prefer more evening light and look forward to the spring time change to daylight saving time," she said. "However, they would not want the sun coming up at 9:00 a.m. in the winter months if we stayed on daylight saving time year-round. Similarly, patients would not want the sun coming up at 4:00 a.m. on the longest day of the year if we stayed on standard time all year round."

Dr. Farmer called for more research before a decision is made.

"I suggest we need more information about the dangers of staying on daylight saving or standard time year-round because perhaps the current strategy of keeping morning light consistent is not so bad," she said.

Time for a Congressional Hearing?

According to Dr. Ramar, the time is now for a Congressional hearing, as lawmakers and the public need to be adequately informed when considering new legislation.

"There are public misconceptions about daylight saving time and standard time," Dr. Ramar said. "People often like the idea of daylight saving time because they think it provides more light, and they dislike the concept of standard time because they think it provides more darkness. The reality is that neither time system provides more light or darkness than the other; it is only the timing that changes."

Until new legislation is introduced, Dr. Ramar offered some practical advice for navigating seasonal time shifts.

"Beginning 2-3 days before the time change, it can be helpful to gradually adjust sleep and wake times, as well as other daily routines such as meal times," he said. "After the time change, going outside for some morning light can help adjust the timing of your internal body clock."

The investigators reported no conflicts of interest.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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