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Should daylight saving time be made permanent? Why health experts say no

Efforts are underway to "lock the clock" and stick with one time all year long. Doctors say it shouldn't be DST.
Photo Illustration/Getty Images
/ Source: TODAY

In a few weeks, we’ll once again “fall back” one hour to standard time, ushering in more light in the morning and earlier darkness at night as winter nears.

Or will we?

There’s a new entry in the push to “lock the clock” — the effort to stop the country from moving in and out of daylight saving time, which is currently in place from mid-March until early November.

Two U.S. senators from Florida, Marco Rubio and Rick Scott, have introduced a bill to keep DST in place through the fall of 2021, noting the nation “could use a little more sunshine” after months of staying inside amid the coronavirus crisis.

The bill has been placed on the Senate calendar.

“More daylight in the after school hours is critical to helping families and children endure this challenging school year,” said Rubio, who last year also introduced legislation that would make daylight saving time permanent across the country.

President Trump has also expressed support for making the move.

But sleep experts worry that’s the wrong way to go and could pose health risks.

Can daylight saving affect your health?

There is no biological need for humans to change the time twice a year, though the health impact can be concerning, sleep experts said.

“There is no great reason to switch back and forth… it is disruptive in a lot of different ways,” Dr. Meir Kryger, a sleep researcher and professor at the Yale School of Medicine in New Haven, Connecticut, told TODAY.

“We have evidence accumulating that it’s dangerous to do this,” added Dr. Charles Czeisler, chief of the division of sleep medicine at Brigham and Women’s Hospital in Boston and professor at Harvard Medical School.

The effects are particularly evident in the spring, when people face a greater risk of heart attack and stroke in the days after losing one hour of sleep. There are also more car accidents, medical errors and hospital admissions.

The change causes a phase shift of our circadian rhythm — the body’s internal clock — and exacerbates the chronic sleep deficiency Americans already experience.

“Many people in our society are living on the edge in terms of the amount of sleep that they’re getting,” Czeisler said.

The fall time change has consequences, too, potentially increasing symptoms of depression in people whose depression is linked to darkness, Kryger said.

What are the negative effects of daylight saving time?

Beyond the question of whether we should stop changing the time twice a year, there’s the issue of which time should be made permanent: standard or daylight saving time.

In August, the American Academy of Sleep Medicine called for the seasonal time changes to be abolished in favor of year-round standard time, noting it most closely matched our sleep-wake cycle.

“The standard time is more standard as far as the body is concerned,” Kryger noted.

Daylight saving time, on the other hand, is less aligned with human circadian biology because it means more darkness in the morning and more light in the evening, disrupting the body’s natural rhythm, the academy cautioned.

The Society for Research on Biological Rhythms also advocated for permanent standard time based on studies that found that the further west people lived within a time zone — thus experiencing a later sunrise that would also come with DST — the more health problems they had, including increased rates of cancer.

“It affects when you are exposed to light and light impacts the release of the sleep-promoting hormone melatonin,” Czeisler said. “Melatonin is also an oncostatic agent, meaning that it slows the growth of cancer.”

Beyond health, there are also safety concerns, especially when it comes to children waiting for school buses on dark mornings.

If daylight saving time were permanent, the sun would not rise in December and January until after 9 o’clock in major cities like Detroit, Indianapolis and Seattle, and about 8:30 a.m. in New York and Chicago, according to David Prerau, author of "Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time."

Why do we have daylight saving time?

The concept of extending daylight hours to conserve power has been around since World War I. It was thought a later sunset would lead to less lamp use in the evening, but the savings have been underwhelming — about 0.5% in total electricity per day.

DST became law in the U.S. in 1966, with the start and end dates extended twice since, leading to the current eight-month span.

States can opt out of daylight saving and stick with standard time permanently — which is the case with Arizona, Hawaii, the U.S. Virgin Islands and Puerto Rico.

But making daylight saving time permanent year-round is not currently allowed by federal law and would require an act of Congress to make a change, according to the National Conference of State Legislatures.

Are we going to stop changing the clocks?

So far this year, at least 32 states have considered legislation to establish DST as the official time year-round — and in the last three years, 13 states have enacted it if Congress were to allow such a change, the group noted.

Scott Yates, a “lock the clock” activist in Denver, advocates following the European Union, which plans to stop the clock changes by 2021 and let member countries decide whether to permanently stick with winter or summer time.

Yates believes it should be up to each state in the U.S., even though that might result in a patchwork of times.

“Once the states are locked into their time zone, we'll know what their relationship is to our home states, and that won't change, so less confusion overall,” he said.

“I am hopeful that a combination of state legislative action and real bipartisan efforts in Washington will end (seasonal clock changes) in the next year or two. When we see that Europe can do it, we'll know that we can do it, too.”