It’s that time of year again — one of the two biannual time changes, this return to standard time. While Americans dislike the “fall back” change less than the “spring ahead” to daylight saving time (DST), both are unpopular. More than half of the Americans would prefer an end to these changes, in fact.

But beyond the inconvenience and annual loss of an hour of sleep in the spring, there’s the potential for health consequences associated with the time changes. These can range from minor issues, such as a lower ability to concentrate at work, to more serious ones, such as car accidents. One of the long-held beliefs — stemming from old research — is that time changes lead to a spike in myocardial infarctions. New research suggests that’s not the case.

Jennifer Rymer, MD, of the Division of Cardiology at Duke University Hospital in Durham, North Carolina, led a study on the association of DST with incidence and outcomes of myocardial infarction. Her findings? There is no significant association between DST and the outcomes of patients presenting with myocardial infarction. “Many of us wonder if there was truly a link, and so we looked at the numbers from a large database,” said Rymer.

The database included nearly 170,000 patients from the Chest Pain MI Registry from 2013 to 2022. Rymer’s team looked at patients who presented 1 week before DST, during the week of DST, and 1 week after DST. But it went a step beyond just the period surrounding the time change.

“We separated out those places like Arizona that don’t change their clocks,” said Rymer. “Again, we saw no increases, which is an important finding.”

According to Rymer, there are several reasons why this study differs from prior findings. For one, its size is much larger and more heterogeneous than that of previous studies. This study is also the first to consider the data without the inclusion of states that don’t change time. There’s also the theory that the transition to remote work since the pandemic has meant that time changes have a lower impact on people’s health.

But perhaps the biggest reason for the differences in the older research and Rymer’s is that improvements in medicine have helped change the math when it comes to heart attacks. “There’s been an overall decrease over time in the number of heart attacks, so now we don’t see the increased association with the time change,” said Rymer.

That’s not the end of the story, however. There are other health considerations that suggest that an end to time changes could be helpful.

Stroke and Obesity Risks

While myocardial infarction impacts during time changes could now be a nonissue, researchers have uncovered other issues worth your attention. A new study out of Stanford University says that the prevalence of obesity and stroke would be reduced if the nation stuck to one time year-round. The key here is lessening the burden on the circadian system, according to bioengineering PhD candidate Lara Weed in the Zeitzer Circadian Research Project. “We look at circadian rhythms and models and try to understand how that internal clock is regulated in terms of synchronization with the external world,” she said.

In a perfect world, the body gets to predict its needs across a given day. Hunger at lunch, for instance, or the urge to exercise at the beginning of the day. This bleeds over into sleep, too. Going to bed when tired in the evening and rising again in the morning after a full night’s sleep is ideal. Modern life, however, often gets in the way, time changes included.

“We run into health problems when we disrupt our circadian rhythms,” said Weed. “This can happen acutely when the time changes. We see higher incidents of car accidents or a decrease in workplace engagement.”

When this carries over to more chronic sleep disruption and deprivation, as with swing shift workers, the issues get bigger and more impactful. But when it comes to the biannual time changes, there is still an argument for a permanent switch to standard time, according to Weed. “Ranking from worst to best is the biannual change, then daylight savings, and then standard time,” she said. “From a circadian rhythm perspective, permanent standard time is most helpful.”

Using a CDC dataset and modeling, the Stanford team determined that the drop in obesity and stroke incidents would be small by transitioning to 1 year-round change. “But in the United States, that can have an impact,” she said.

There are calls for the end of the time change, not just from this research or a sleepy public. The Coalition for Permanent Standard Time, for instance, is a group of organizations — many of them medical — that advocate for this change. Members include the American Academy of Sleep Medicine (AASM), the National Sleep Foundation, and the American College of Chest Physicians.

Emerson Wickwire, PhD, a professor and section head of sleep medicine at the University of Maryland School of Medicine in Baltimore and a spokesperson for the AASM in Darien, Illinois, is deeply in favor of a permanent switch. In the meantime, he counsels doctors to tune into their patients around the time changes. Shift workers, patients with sleep disorders, or those who work in safety industries like transportation can be particularly affected.

“If they’re starting at a baseline of sleep loss, losing that hour in the spring can be significant,” he said. “Those are your highest-risk patients.”

But also use the time changes to educate your patients on the importance of good sleep routines and hygiene, said Wickwire. “Make sure they’re obtaining 7-9 hours in bed each night,” he said. “Too often, physicians don’t ask patients about their sleep habits, and the patients don’t share that information. You can improve their quality of life and health outcomes by helping them get the sleep they need.”

Science is ever evolving, which is why awareness of the most up-to-date studies on time changes is essential. Armed with this information, as a primary care physician, then, how should you approach your patient’s health in the weeks following time changes? “You should always be mindful and be on the lookout when it comes to your patients’ cardiovascular health,” said Rymer. “But when it comes to daylight savings time, you can breathe a little easier.”