Common Core: RH.6-8.1, RH.6-8.2, RH.6-8.4, RH.6-8.6, RH.6-8.8, WHST.6-8.1, WHST.6-8.4, RI.6-8.1, RI.6-8.2, RI.6-8.4, RI.6-8.6, RI.6-8.8, RI.6-8.10, W.6-8.1, W.6-8.4, SL.6-8.1

NCSS: Power, Authority, and Governance • Science, Technology, and Society

Illustration by James Yamasaki


Expert vs. Expert

Should We Stop Changing the Clocks?

Illustration by James Yamasaki

Get ready for some extra Zzz’s! Before bed on November 5, most Americans will turn their clocks back one hour. If you’re one of them, you’ll end up with 60 more minutes to snooze the next day. 

The clock switch marks the end of daylight saving time (DST), a time system that most states use for part of the year. DST starts in March, when Americans move their clocks ahead one hour. That shifts 60 minutes of sunlight from morning to evening during spring and summer, when daylight lasts longest. DST ends in November, with standard time resuming as daylight hours shorten. 

Not everyone likes switching back and forth from DST though. Critics say changing the clocks is harmful to people’s health. Some of them want to get rid of DST entirely, while others want it to last year-round. 

Members of the U.S. Senate, for example, passed a bill this year to make DST permanent. To become law, the bill would need approval by the U.S. House of Representatives and President Joe Biden. 

Still, some people think the current time setup works best. They say using DST only in the spring and summer encourages people to be more active during those seasons, while still maximizing daylight hours in the fall and winter. 

Two experts—a neuroscientist and an author—weigh in.


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 controls other physiological processes such as breathing. 

A one-hour time change throws our body clocks out of sync. And that can have negative health consequences: We think we’re hungry when we’re really not, our immune systems function less efficiently, and our risk of certain cancers goes up.

Using standard time all year is better for our health.

The time change ritual also disrupts our sleep. A 2015 study found that high school students lose an average of 32 minutes of sleep per night in the weeks after the time change. That translates to groggy students and lost learning. 

Being less alert is dangerous for everyone. In the days after we switch the clocks, we consistently see an uptick in traffic accidents. We also see a higher number of heart attacks. These are not trivial effects, and they’re why most scientists oppose the current system. 

Using standard time year-round would be a better choice for our health. It would keep our body clocks better aligned to the rising and setting of the sun. That would help all the systems in our bodies function optimally.

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

—Joseph S. Takahashi
Investigator, Howard Hughes Medical Institute


The current time system is 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 changing our clocks to DST from spring into fall reduces crime, lowers energy usage, and encourages physical activity and quality of life by getting people outdoors. 

Changing clocks helps us maximize daylight.

But using DST all year is a bad idea because it makes already-late winter sunrises an hour later. In 1974, the U.S. government tried adopting DST year-round. During the winter, children had to walk to school in the dark or wait for school buses in the dark. The change was so unpopular that it was discontinued after one year.

If we were to use standard time all year, many spring and summer sunrises would be much earlier than 6 a.m. That would waste sunlight that’s better used later in the day. Since 1966, states have been allowed to use standard time all year. But only two states do. Hawaii is near the equator, where daylight hours vary little throughout the year. Arizona has extreme summer heat, so people there eagerly await sunset to go outdoors. 

There are significant drawbacks with both permanent standard time and year-round DST, so we should continue to change the clocks twice a year. The negative effects last just a few days, and the annoyance is a small price to pay for a solution that gives us the advantages of both time systems.

—David Prerau
Author of Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time

SKILL SPOTLIGHT: Evaluating Arguments

How do the authors support their claims? Underline two reasons each author gives. Then decide who makes the stronger argument. Write a brief explanation for that choice. Include details from the text in your answer.

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Skills Sheets (2)
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