Political Support of Permanent DST Concerns Sleep Scientists

Christine Kilgore, MDedge News

July 16, 2021

The reintroduction of congressional bills that aim to end seasonal time change and move permanently to daylight saving time (DST) – and action on the issue by 19 states in the last 4 years – signal political momentum and up the ante on sleep medicine to educate others and to more uniformly weigh in on the health consequences of such a change.

This was the message of several sleep scientists and physicians who participated in moderated discussions of DST at the virtual annual meeting of the Associated Professional Sleep Societies.

A position paper issued about a year ago by the American Academy of Sleep Medicine objected to the proposed switch and instead called for elimination of DST in favor of permanent standard time (ST). While there are detrimental health effects with time changes in either direction, there is "abundant" evidence that the transition from standard time to daylight saving time is worse, the AASM statement says.

Some experts have questioned, however, whether the evidence is weighty and comprehensive enough to drive a change in national policy. Others, such as SLEEP 2021 discussant Karin Johnson, MD, say there is unawareness outside of sleep medicine – and even within – of a growing body of literature on circadian misalignment and its associated health risks.

"There's an educational gap for what's out there [in the literature]," Johnson, medical director of the Baystate Health regional sleep program and Baystate Medical Center sleep laboratory in Springfield, Mass., said in an interview after the meeting.

Calls for more research, particularly on the chronic effects of DST and ST, are concerning because discussions of abolishing seasonal time change are "moving forward with or without us," Kenneth Wright Jr., PhD, director of the chronobiology laboratory at the University of Colorado in Boulder and professor in the university's department of integrative biology, said at the meeting.

"We don't have time ... to have the studies we'd need to prove unequivocally that permanent standard time [is best]. We need to consider the scientific evidence before us – what's known about human biology and health with respect to light and circadian timing," Wright said. "The argument that pushing our clocks later is going to be healthier is not tenable. We cannot support that given the vast amount of scientific evidence we have from circadian and sleep science."

Underscoring the sense of urgency to be engaged in the issue were the messages of Rep. Raymond Ward, MD, PhD, a Utah legislator in the state's House of Representatives who introduced a bill to permanently observe DST, pending the amendment of federal law to permit such a change, and provided that five other Western states enact the same legislation.

"I chose to support DST because I became convinced this is the only thing that's politically possible," said Rep. Ward, a family practice physician at the Ogden Clinic in Bountiful. National polls have shown a "strong preference" to end seasonal time change, he said, and a poll conducted in his district showed that nearly 80% "wanted to stop changing the clocks, and 65% wanted the summer time schedule."

"To me, the train seems to be moving in one direction," said Rep. Ward. "The bills open in Congress in both the House and the Senate don't have enough support yet, but every time another state legislature passes [legislation to establish permanent DST], they pick up a few more supporters."

The Sunshine Protection Act of 2021 introduced in the House in January by Rep. Vern Buchanan (R-Fla.) has 23 cosponsors, and a bill of the same name introduced in the Senate in March by Marco Rubio (R-Fla.) has 14 cosponsors. Both bills have bipartisan support and are reintroductions of legislation initially put forth in 2019. A press release issued by Sen. Rubio's office says that "extending DST can benefit the economy and our overall health."

According to the National Conference of State Legislatures, 19 states have enacted legislation or passed resolutions in the last several years to provide for year-round DST, if Congress were to allow such a change. And according to a Congressional Research Service (CRS) report on DST updated in September 2020, at least 45 states have, since 2015, proposed legislation to change their observance of DST.

These efforts include proposals to exempt a state from DST observance, which is allowable under existing law, and proposals that would establish permanent DST, which would require Congress to amend the Uniform Time Act of 1966, the CRS report says.

The State of the Science

Shifting from ST to DST has been associated with an increase in cardiovascular morbidity (heart attacks and atrial fibrillation), increased missed medical appointments, increased ED visits, increased mood disturbances and suicide risk, increased risk of fatal car crashes and medical errors – and sleep loss, said Elizabeth Klerman, MD, PhD, professor of neurology in the division of sleep medicine at Harvard Medical School, Boston.

These associations are covered in AASM statement, along with acknowledgment that most studies on the chronic effects of DST have "either been retrospective or addressed the issue indirectly."

For Johnson, who refers to DST as "sleep deprivation time," the most convincing data regarding the dangers of permanent DST come from studies comparing locations within time zones. "The farther you're off from the meridian, the more you have that 'social jet lag' or circadian misalignment [between the innate circadian rhythm, which is synchronized with solar time, and school or work schedules]," she said at the meeting.

Researchers reported in 2017, for instance, that the risk for all cancers and many specific cancers increased from east to west within a time zone, as solar time is progressively delayed. "They documented changes in risk for every 5 degrees west from the meridian," she said.

Johnson is a case in point of the "educational gap" that she believes needs attention. Two years ago, as chair of the sleep section of the American Academy of Neurology, she delved into the literature after the AAN asked the section whether it should endorse the AASM's position paper on DST. "I didn't know the literature even as a sleep scientist until I got into this," she said.

"If you're asked me 2 years ago," she added in the later interview, "I would have said that permanent DST is fine."

The sleep section recommended that the AAN endorse permanent ST, but the AAN ultimately decided it "didn't feel strongly enough to say that standard time is unequivocally the better option," Johnson said in an interview. "They agreed that there's science [in favor of it], but ... it's a big public policy decision."

Jamie Zeitzer, PhD, associate professor of psychiatry and behavioral sciences at Stanford (Calif.) University's Center for Sleep Sciences and Medicine, voiced similar concerns at the meeting about currently advocating a shift in either direction. It's "absolutely clear that switching clocks, especially since it's occurring at a population level, is deleterious and we need to get rid of it," he said. "But before we put forth dictates on public health [with a shift to permanent ST], I think we better be sure we're correct."

"I think we're getting close. I think the data thus far [are indicating] that permanent standard time is better for health," Zeitzer said. "But I don't think there's a cumulative amount of evidence to really say that we have to subvert all other interests because this is so important for public health. We need at least a few more studies."

There is not enough evidence, for instance, to conclude that the body clock does not eventually adjust to DST, he said, and it is not yet clear what roles electric light and sunlight each play in the body's circadian time.

"And we need to think about north-south. What may be important for the upper Midwest, and for Maine, and for Washington, may not be ... good for Florida and Texas and southern California," Zeitzer said. "You have very different patterns of light exposure, especially when it deals with seasons."

Historical Considerations

In his comments at the meeting, Muhammad Rishi, MBBS, the lead author of the AASM's position statement, added that circadian misalignment – that "asynchrony between the internal and external clocks" – is associated in studies with an increased risk of obesity, metabolic syndrome, and depression.

But he also emphasized that the "historical evidence" against permanent DST is at least as strong as the medical evidence.

"The U.S. has gone on permanent daylight savings time several times in the past, most recently in the 1970s during the OPEC [oil embargo], and it was so unpopular," said Rishi, of the department of pulmonology, critical care and sleep medicine at the Mayo Clinic Health System in Eau Claire, Wis. "England also did it in the 1960s and then abolished it, and most recently Russia did it ... it became so unpopular with increased depression and mood disorders that they abolished it."

Rep. Ward said that China has offered a large natural experiment with its move decades ago from five time zones to one time zone – Beijing time. "I don't think we've seen any sweeping changes in their health because they have one large time zone," he said.

Klerman took issue, saying she "knows someone in China who is trying to get that data about health outcomes and is unable to get it."

Arguments that DST saves energy hold little to no weight upon scrutiny of the data, Johnson said. Moreover, research other than oft-cited, older Department of Transportation studies suggests that "permanent DST is bad for energy and bad for the climate," she said. "This really needs to be more fully evaluated by the government and others."

Johnson said after the meeting that it's important for experts from the energy and climate sectors, education, and medicine – including pediatrics, oncology, and other specialties with "a stake in this" – to come together and share information so "we won't all be in our silos." She and other sleep experts in the neurology field are planning to host a summit in 2022 to do just this.

Johnson and Kin Yuen, MD, of the Sleep Disorders Center at the University of California, San Francisco, both expressed concern at the meeting that adoption of permanent DST would negate the benefits of delayed school start times in middle and high school students.

There is some evidence that delayed start times have led to decreased tardiness and absences, Yuen said. To have the same impact with permanent DST, "instead of starting at 8:30 a.m., you'd have to start at 9:30," Johnson added after the meeting.

The first discussion of DST at the SLEEP 2021 meeting was led by Erin E. Flynn-Evans, PhD, MPH, director of the Fatigue Countermeasures Laboratory at the National Aeronautics and Space Administration Ames Research Center. Yuen led a later second question-and-answer session. They and each of the eight participants reported that they had no relevant conflicts of interest.

Yuen and Flynn-Evans are both coauthors of the AASM's position statement on DST. Klerman is a coauthor of the Society for Research on Biological Rhythms 2019 position paper on DST.

The AASM's statement has been endorsed by 19 organizations, including the American College of Chest Physicians, the SRBR, the American Academy of Cardiovascular Sleep Medicine, the Society of Behavioral Sleep Medicine, the National PTA, and the American College of Occupational and Environmental Medicine.

This article originally appeared in Chest Physician.


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