President-elect Trump proposed ending daylight saving time. Here's what that could look like in Illinois

Just over a month after clocks "fell back" to standard time upon the ending of daylight saving time across much of the United States, President-elect Donald Trump proposed ending the practice of springing forward and falling back.

In a post on TruthSocial, Trump wrote, "The Republican Party will use its best efforts to eliminate Daylight Saving Time, which has a small but strong constituency, but shouldn’t! Daylight Saving Time is inconvenient, and very costly to our Nation."

While Trump's position seemed to garner an endorsement from advisers Elon Musk and Vivek Ramaswamy, the president-elect's son, Donald Trump Jr., appeared to back the opposite position.

The younger Trump's position is consistent with a bill the Senate passed in 2022 that would have made daylight savings time permanent beginning the following year.

The Trump campaign did not immediately respond to questions from NBC News clarifying whether Trump seeks to eliminate daylight savings time or make it permanent.

Here's what to know about daylight saving time and how a switch back to full standard time would impact Illinois and the Chicago area.

What is daylight saving time?

Daylight saving time is a changing of the clocks that typically begins in spring and ends in fall in what is often referred to as "spring forward" and "fall back."

Under the conditions of the Energy Policy Act of 2005, daylight saving time starts on the second Sunday in March and ends on the first Sunday in November.

On those days, clocks either shift forward or backward one hour.

But it wasn't always that way.

Clocks used to spring ahead on the first Sunday in April and remained that way until the final Sunday in October, but a change was put in place in part to allow children to trick-or-treat in more daylight.

In the United States, daylight saving time lasts for a total of 34 weeks, running from early-to-mid March to the beginning of November in states that observe it.

Some people like to credit Benjamin Franklin as the inventor of daylight saving time when he wrote in a 1784 essay about saving candles and saying, "Early to bed, early to rise makes a man healthy, wealthy and wise." But that was meant more as satire than a serious consideration.

Germany was the first to adopt daylight saving time on May 1, 1916, during World War I as a way to conserve fuel. The rest of Europe followed soon after.

The United States didn't adopt daylight saving time until March 19, 1918. It was unpopular and abolished after World War I.

On Feb. 9, 1942, Franklin Roosevelt instituted a year-round daylight saving time, which he called "wartime." This lasted until Sept. 30, 1945.

Daylight saving time didn't become standard in the US until the passage of the Uniform Time Act of 1966, which mandated standard time across the country within established time zones. It stated that clocks would advance one hour at 2 a.m. on the last Sunday in April and turn back one hour at 2 a.m. on the last Sunday in October.

States could still exempt themselves from daylight saving time, as long as the entire state did so. In the 1970s, due to the 1973 oil embargo, Congress enacted a trial period of year-round daylight saving time from January 1974 to April 1975 in order to conserve energy.

When will DST resume?

In 2025, daylight saving time will resume on March 9, with clocks springing forward then.

Which states observe daylight saving time?

Nearly every U.S. state observes daylight saving time, with the exceptions of Arizona (although some Native American tribes do observe DST in their territories) and Hawaii. U.S. territories, including Puerto Rico, American Samoa, Guam and the U.S. Virgin Islands, do not observe daylight saving time.

Which is better for your sleep?

According to Dr. James Rowley, a professor of medicine at Rush University and the immediate past president of the American Academy of Sleep Medicine, the changing of the clocks could actually do more harm than good.

The topic of daylight saving time vs. standard time has been hotly debated, particularly in recent years. Sleep experts have advocated in some cases for a permanent standard time. But some experts say switching to permanent daylight saving time, as some lawmakers previously suggested, would be worse.

"Permanent standard time would basically mean that we were on what is, I guess, biologically the correct time all year round. And I'm going to say biologically correct because our bodies are more used to and have evolved to be on what would be considered standard time over the years," Rowley told NBC Chicago in an interview. "Permanent daylight savings time, the particular problems come in at winter. It is great to have 'the extra hour of sunlight' in the evening, although I always remind people, we have the same amount of sun, you know, in the summer, whether it's daylight or standard time, but just that seems to be an hour later. But in the winter time, sunrise is much later, and that's very problematic biologically, because we need sunshine in the morning to set our circadian rhythms for the day."

The American Academy of Sleep Medicine has pushed for a switch to permanent standard time for several years.

“By causing the human body clock to be misaligned with the natural environment, daylight saving time increases risks to our physical health, mental well-being, and public safety,” Dr. M. Adeel Rishi, who is chair of the AASM Public Safety Committee and a pulmonary, sleep medicine, and critical care specialist at Indiana University Health in Indianapolis, said in a statement. “Permanent standard time is the optimal choice for health and safety.”

Experts cited a "growing body of evidence" in recent years.

“Permanent standard time helps synchronize the body clock with the rising and setting of the sun,” Dr. James A. Rowley, president of the AASM, said in a release. “This natural synchrony is optimal for healthy sleep, and sleep is essential for health, mood, performance, and safety.”

It also mirrors similar takes from other organizations, including the National Sleep Foundation, which said "seasonal time-changes are disruptive to sleep health and should be eliminated."

How would it affect the Chicago area?

As daylight saving time is observed in Illinois from March to November, sunsets will get as late as 8:29 p.m. under daylight saving time on June 20, which comes with a 5:15 a.m. sunrise, according to timeanddate.com.

If Chicago and the rest of Illinois continued to observe standard time after the early March switch, both the sunrise and sunset times at the peak of summer would be an hour earlier, with a 4:15 a.m. sunrise and 7:29 p.m. sunset.

Maintaining standard time would mean earlier sunsets overall, which would include a 6:03 p.m. sunset on March 20, as opposed to a 7:03 p.m. sunset that Chicago will see on that date next year under the observance of daylight saving time.