Sleep rhythms

Experts say year-round standard time better aligns with the human body’s natural circadian rhythms.

For years, most Americans have gotten up on the morning of the second Sunday of March largely feeling the same way: tired.

But the lingering fatigue that accompanies losing an hour of rest as we “spring forward” to make the jarring switch to daylight saving time is not just a mild inconvenience, sleep experts say.

According to the American Academy of Sleep Medicine, the switch to DST does more than temporarily throw our sleep schedule out of whack: Data shows it poses serious public health and safety risks. And now, members of the prominent sleep organization have made it clear that if they had it their way, the country would finally be rid of the decades-old system of shifting between standard time and DST, which is observed by 48 states and some U.S. territories.

A growing body of evidence prompted the academy to release its first position statement on the subject, recommending that the country eliminate the biannual switches in favor of year-round standard time, which it asserts better aligns with the human body’s natural circadian rhythms.

The statement was published in late August in the academy’s Journal of Clinical Sleep Medicine and received support from more than a dozen other organizations, including the National Safety Council and the National Parent Teacher Association.

While acknowledging it is only one of many voices on the issue, the academy hopes its statement will help reinvigorate debate on the matter.

“There’s been accumulating evidence over the last several years indicating that daylight saving time in general, but even more importantly, the switches between daylight saving time and standard time, are deleterious to health in various realms: cardiovascular health, motor vehicle accidents and crashes, psychological health,” said M. Adeel Rishi, vice chair of the AASM’s public safety committee. Rishi added that the AASM’s position is consistent with the views of other major sleep organizations.

In addition to increased risk of stroke and heightened mood disturbances, studies show a spike in traffic fatalities and medical mistakes in the days immediately following the switch in the spring. One recent paper from the University of Colorado at Boulder examined more than 732,000 accidents over two decades and found that fatal crashes rose by 6% during the first week of DST.

Another research abstract published in May studying the effects of sleep deprivation on health-care workers noted that an 18% increase in adverse medical events related to human error occurred the week after switching.

“The issue is that as a society, we’re so sleep-deprived to begin with that when you add even just one more hour of sleep loss on top of that, you’re pushing people into this zone” of risk, said Philip Gehrman, an associate professor of clinical psychology in psychiatry at the Hospital of the University of Pennsylvania. “It’s like the straw that breaks the camel’s back.”

Although it is widely understood that switching is not ideal for people’s overall health, divisions remain about which schedule should be permanent.

“Lots of people want to get rid of the switch,” said Gehrman, a member of Penn’s Center for Sleep and Circadian Neurobiology. “Whether we stay on permanent daylight saving time or permanent standard time, I think it depends on who you ask and ultimately comes down to when do you want the daylight.”

In recent years, there has been a growing nationwide effort supporting permanent DST. Though critics have cast doubt on the purported energy-saving benefits of DST, advocates argue that it promotes public safety, with evidence linking the extra daylight in the evenings to a decrease in crime.

This year alone, more than 30 states introduced legislation to make DST the new normal, joining eight other states that have already passed similar bills, CNN reported. Adopting permanent DST requires approval from Congress.

But as the academy noted in its position statement, the long-term effects of DST have yet to be thoroughly researched, leading to some disagreement among sleep experts about whether there is enough evidence to definitively say one time system is more beneficial.

“The evidence is very strong that we should get rid of one or the other, but which one, that I think is a little less clear,” said Jamie Zeitzer, an associate professor of psychiatry and behavioral sciences at the Stanford Center for Sleep Sciences and Medicine.

To support its recommendation of permanent standard time, the AASM cited the risk of “circadian misalignment” associated with DST.

“Standard time is going to be your best situation where your social clock, your internal biological clock and your sun clock are going to be more likely, for the most time, to be better aligned,” said Phyllis Zee, chief of sleep medicine at Northwestern University’s Feinberg School of Medicine. She added:

“It may not be true for every single person. It really depends on where you live, whether you’re an owl or a lark. All of these things matter. But I think overall, as a general policy, that would be the healthiest solution.”

Almost everything in the human body, down to the rate at which cells divide, follows a circadian rhythm, Gehrman said. A good circadian rhythm is critical to keeping people’s bodies synchronized internally, as well as with the environment.

“Having good, strong, regular rhythm, and as part of that, rhythms that are in sync with the schedule we’re keeping, . . . it’s just a pillar of good health,” he said.

If the country institutes permanent DST, Rishi said, that may put people at risk of a condition known as “social jet lag.”

“Social jet lag is basically the chronic misalignment between the timing of the demand of work, school or other obligations against innate circadian rhythm,” he said, using an example of a night owl who spends most of their life staying up late and waking up early to meet responsibilities.

“There is evidence that social jet lag is associated with obesity, with metabolic syndrome, with cardiovascular disease, with psychological problems like depression,” he added.

Other sleep experts, however, say more research is needed before the country settles on one time system.

“There’s so much variability in our schedules, and in our circadian rhythms as well, that a switch in either direction is going to help some people and hurt others,” Gehrman said. “To me, it’s not a clear, ‘Yes, this is going to benefit way more people than it’s going to hurt.’ I’m just not convinced that we have the science to say that.”

Meanwhile, Zeitzer questioned the AASM’s stance that standard time aligns better with the body’s natural rhythms.

“I don’t necessarily agree with the argument that it comports better,” he said. “The way our rhythm positions itself is actually quite flexible.”

Still, the experts emphasized the significance of the academy’s statement in bringing fresh attention to the issue of DST, focus that Zeitzer noted has lagged at times.

“We are but one voice in this discussion,” Rishi said. “We would hope that [the statement] would push this toward being a scientific and a public health debate, and that would be the primary concern when the final decision is made on this issue.”

Friday, September 18, 2020