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Should We Stop Changing the Clocks?

February 21, 2022

Most Americans will set their clocks ahead one hour on March 13 for the start of daylight saving time (DST). It’s a ritual that many people complain about and a growing number of lawmakers are trying to end. DST was first adopted in the United States in 1918 as a way to save energy by providing more daylight hours during the evening. It came and went a couple of times before Congress passed the Uniform Time Act in 1966. Since then, most states have been switching clocks twice a year.

In the past four years, 19 states have enacted legislation or passed resolutions to use DST all year—if Congress were to pass a bill to permit it. Last year, Senator Marco Rubio, Republican of Florida, introduced in the U.S. Senate the Sunshine Protection Act, which would make daylight saving time permanent in the U.S. year-round. A similar bill is in the House.

Two experts—a neuroscientist and an author of a book about daylight saving time—face off about whether the U.S. should end its current system of switching back and forth between standard time and DST.

Even though we change the clocks just two times a year, each time we do, the negative effects on our bodies can last for weeks, and they’re significant.

Over billions of years, life on Earth has evolved to operate in sync with the 24-hour cycle of day and night. This circadian rhythm—often referred to as our body clock—tells our bodies when to sleep and regulates many other physiological processes right down to the cellular level.

A one-hour time disruption is enough to throw our body clocks out of sync. And that has many bad health consequences: We lose our ability to regulate our blood sugar. We feel hungry when we’re not really hungry. Our immune systems function less efficiently, and cancer rates increase.

These changes disrupt our sleep, leading us to be less alert during the twice-a-year time change periods. Consequently, we consistently see an uptick in the number of traffic accidents that occur after we switch the clocks. We also see a higher number of heart attacks. These are not trivial effects, and they’re why most scientists oppose the current system of twice-a-year time changes.

The one-hour time change disrupts our body clocks and harms our health.

Changing the clocks is also very disruptive to people’s routines. A 2015 study found that high school students lost an average of 32 minutes of sleep per night in the weeks after the time change. That translates to a lot of groggy students and lost learning.

If we stop changing the clocks, we need to pick either standard time or daylight saving time (DST). While many politicians and lobbyists for the leisure industry would prefer to use DST all year round, using standard time year-round would be a better choice for our health. That’s because standard time keeps our body clocks better aligned to the rising and setting of the sun, and that helps all the systems in our bodies function optimally.

For these reasons, we should abolish daylight saving time, eliminate the damaging hassles of the twice-a-year time switch, and remain permanently on standard time.

—JOSEPH S. TAKAHASHI

Professor of Neuroscience, University of Texas Southwestern Medical Center

There are many advantages to the current time system: spring-to-fall daylight saving time (DST) and winter standard time. It’s an excellent compromise, providing the many benefits of DST most of the year and yet avoiding problems of winter DST during the darkest, coldest months.

Numerous studies show that spring-to-fall DST reduces deaths from traffic accidents, reduces crime, increases public health and quality of life by getting people outdoors, and reduces energy usage.

But using DST all year is a bad idea because it makes already-late winter sunrises an hour later. It’s also an idea we’ve already tried. In 1974, the federal government adopted DST year-round. The concept seemed popular when proposed but quickly lost favor. People disliked the pitch-dark winter mornings for going to work. They especially disliked sending children to school on very dark mornings—walking dark streets or waiting for school buses on dark roads. It was so unpopular that Congress discontinued a two-year trial after one year.

Changing the clocks gives us the advantages of both time systems.

If we used standard time all year, many spring and summer sunrises would be much earlier than 6 a.m.—while most people are sleeping—wasting daylight that’s better used later in the day. Since 1966, all states have been allowed to remain on standard time all year. But only two states choose to do that—for very specific reasons. Hawaii is near the equator, where daylight hours vary little throughout the year. With Arizona’s extreme summer heat, people don’t want more daylight; instead, they eagerly await sunset to go outdoors.

Since there are significant drawbacks with both permanent standard time and year-round DST, we should keep the beneficial compromise time system now in use. It’s true that some people find changing the clocks twice a year to be troublesome. But the effects last just a few days, and the annoyance is a small price to pay for a compromise solution that gives us the advantages of both time systems.

—DAVID PRERAU

Author, Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time