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Daylight Saving Time Is Bad For Our Internal Clocks, Too

7 minute read

On a recent trip to Tucson, I heard zero complaints about a pending hour of lost sleep. On March 10, 2024—when most clocks across the country will advance one hour for daylight saving time—no one in that city will be scrambling to remember how to adjust the time on their microwaves or car dashboards. And as the leaders of nearby states, including my home state of Washington, hold hearings about whether to ditch the antiquated practice of springing forward and falling back—with fiercely opposing views about which way to lock the clock—Arizona leaders have no need. The state has run on standard time since 1968.

Most of the rest of us are set to repeat the biannual dance. Research tells us that changing our clocks burdens us with a host of health and safety problems, on top of the annoyances. The polls tell us that we widely agree we should stop. Congress even permits us, and scientific and medical experts beg us, to follow the lead of Arizona and Hawaii and opt out of daylight saving time in favor of full-time standard time. Yet, here we still are fiddling with our clocks, without an end to the practice in sight.

Over the last few weeks, Oregon and Washington fell shy of advancing respective permanent standard time legislation. Other states continue to debate similar bills—all of which seem to have been introduced out of impatience. Oregon and Washington are among more than a dozen states that have already passed legislation for the more publicly popular year-round daylight saving time. But that move is contingent on Congress changing federal law to allow for it. And momentum has waned. The latest iteration of the Sunshine Protection Act, which nearly passed in 2022, has fewer cosponsors. The question of “What time is it?’ has become a political hot potato.

It is time to break from this bickering and shift the conversation from the clocks on our walls and wrists to the clocks within us.

A symphony of tiny timekeepers tick—metaphorically, of course—throughout your body. Circadian clocks keep time everywhere from your liver and lungs to your nose and toes. They rely on the planet’s predictable patterns to stay harmonized and, in turn, to keep your brain and body running optimally. The most powerful of these cues is the rising and setting sun. Seeking bright mornings and dark evenings helps ensure your daily rhythms of alertness, metabolism, and strength, among other aspects of your physiology, peak at the right times. Standard time helps us accomplish both. It concentrates daylight hours earlier. Scientists have even estimated the impact of allocating that controversial hour to the morning versus the evening by comparing people who live at opposite edges of time zones. On the western side, where the sunrise occurs at a later clock-on-the-wall time, studies find lower wages and higher rates of cancer, suicide, and car accidents. That extra hour of natural light at night on the western side further robs people of an average of 19 minutes of sleep each night. Springing forward an hour mimics a move from the east to west edge of a time zone and exacerbates the deficits of those already there. Still, observing daylight saving time is far from the only wrench we throw in our biological clockworks.

Read More: Daylight Saving Time Is the Worst

On average, Americans and Europeans spend more than 90% of their time indoors—under artificial light that is orders of magnitude dimmer than sunlight and orders of magnitude brighter than moonlight. We eat, work, and play at all hours of day and night. Modern life dampens crucial time-telling signals, blurs the boundaries of day and night, and confuses our internal clocks. This disruption may be invisible to us, but the consequences can be profound. They range from poor sleep, reduced productivity, and altered mood to greater risks of weight gain, digestive disorders, and heart disease.

Thankfully, the burgeoning field of circadian science points to surprisingly simple fixes for our broken inner clocks. As individuals, we can get outside in the morning. Even 20 minutes under cloudy skies will do. We can gravitate closer to windows—or, if we have access, use novel lighting systems that aim to mimic natural daylight—while indoors throughout the day. We can dim our lights after the sun goes down and avoid late-night snacks or drinks. As communities, we can reorient schedules around natural cycles rather than an outdated social time architecture, with the ambitious goal of rendering alarm clocks obsolete. We can revise or relax when we require employees and students to arrive in the morning. Early start times are particularly problematic for teens whose circadian rhythms naturally drift later. Missing morning light, almost a given when school bells ring before sunrise, exacerbates teens’ predilection to stay up late. At the urging of the American Academy of Sleep Medicine and the American Medical Association, among other organizations, a growing number of middle and high schools are now changing their start times to 8:30 a.m. or later.

These same organizations recommend adopting permanent standard time. Because we tend to debate the concurrent issues separately, however, we may easily overlook how permanent daylight saving time would erase the published gains in attendance, grades, and test scores from delaying school start times. In Seattle, locking the clock on daylight saving time would push sunrise to after 8:30 a.m. for more than two months of the year—cancelling out the recent bell changes made by Seattle public schools. And we may easily have forgotten what it’s like to endure a winter without morning light. The last time Americans tried permanent daylight saving time was during the energy crisis in the 1970s. That change was short-lived. Concern over children’s safety during dark winter mornings quickly compelled the country to turn back the clocks. The promised energy savings never fully manifested anyway.

As we focus attention on our internal clocks, fixing our external clocks on standard time should become a more popular and achievable goal. We may not have far to go. In the same 2023 YouGov survey that showed Americans preferred permanent daylight saving time over standard time, people still ranked healthy circadian rhythms and not forcing kids to go to school in the dark as the most important values when “choosing the optimal system.” The phrasing of polls and bills likely bias responses. The Sunshine Protection Act is one case in point. Alberta, Canada also narrowly voted down a referendum in October 2021 in which voters were asked if they wanted to adopt “summer hours.”

Read More: Where the Push to Make Daylight Saving Time Permanent Stands

Unfortunately, there is no way to lengthen daylight hours in the winter to resemble blissful midsummer days and nights. We can’t offset the Earth’s tilt. But by correcting the mismatches in messaging and understanding, we can at least begin to fix the mismatches between our external and internal clocks. We can begin to recreate the consistency and the contrasts that our circadian rhythms crave.

Tucson’s geography is a boon for residents’ biological timekeeping. Its proximity to the equator—especially compared to my hometown of Seattle—keeps daylengths relatively consistent across the seasons. The days are also consistently bright, and the nights consistently dark. A friend who recently moved from Seattle to Tucson said he rarely veers from his new daily schedule of early mornings and early nights. In the summer, Tucsonans rise early to avoid the heat. The rest of the year, he told me, it's “out of habit.”

I bathed in the light-dark contrasts during my stay at an Airbnb on the outskirts of town, a welcome change from dreary Seattle. I was surprised at how effortlessly I awoke on my fifth morning to join my friend’s daily 7:30 a.m. breakfast meet-up group. While in Tucson, I also spoke with Jay Pea, president of Save Standard Time, a nonprofit advocating for permanent standard time. Arizona’s rejection of daylight saving time was a leading factor in his recent decision to relocate from California. As he reminded me, Arizona is not alone. Most countries around the world don't change their clocks twice a year.

“Let’s try to define time as objectively as possible,” he told me. “We can work it out from there.”

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