During his medical residency at a local hospital, San Antonio doctor Camilo Gonima always hated when the clock struck 2 a.m. on the last night of daylight saving time. It’s the only time of year a 7 p.m. to 7 a.m. shift lasts 13 hours instead of 12.

“The most painful thing in the world is being on a busy night shift at the hospital, or anywhere, and having to start the whole hour over again,” Gonima said.

Some people might welcome the extra hour of sleep when clocks change on Sunday, Nov. 7. But every year, the ritual sparks a debate about why most of the U.S. does daylight saving time in the first place.

The issue has come up repeatedly in the Texas Legislature, where San Antonio has become a hotbed of bipartisan anti-daylight-saving-time legislating.

Since at least 2015, Democratic state Sen. José Menéndez and Republican state Rep. Lyle Larson have repeatedly introduced bills that would end March and November clock-switching for good.

“The dumbest collective human experience we exercise twice a year is switching our clocks back one hour — and then forward one hour four months later,” Larson wrote in an op-ed published this week.

What’s blocked these bills so far? It turns out that Texans have a difficult time agreeing which time zone the state should choose and stick with — Eastern, Central, or Mountain — according to an explainer by the Texas Tribune. Currently, all of Texas falls within Central time, except for parts of Far West Texas: El Paso and Hudspeth counties and the northwest corner of Culberson County, which lie in the Mountain time zone.

“Whenever a daylight saving time bill comes up for a committee hearing, a number of Texans testify against the legislation solely because they don’t like the time zone … the bill would set as the state’s standard,” the article states.

States are allowed to opt out of daylight saving time, though the only two that have done so are Arizona and Hawaii. Most people say the practice hearkens back to a more agrarian American past.

“I always thought it had to do with farming,” Gonima said.

But the idea that farmers are to blame is one of daylight saving time’s most common myths. In fact, early daylight saving time policy was a matter of war and energy scarcity that originated in the early 20th century.

During World War I, the German Empire was the first national government to impose hours meant to maximize productivity during daylight hours to save fuel. Weeks after April 30, 1916, when Germans first set their clocks forward one hour, other European countries began following suit.

In the U.S., the change came in 1918 under the Standard Time Act, also the first attempt to set an official national policy on time zones. It included a measure that allowed states to enact daylight saving time.

Farmers were generally opposed to the practice, according to Michael Downing, a Tufts University lecturer and authority on American daylight saving time lore who died in February. Many complained it left them gathering eggs and milk cows in the early morning darkness.

“People thought they were wasting these early morning hours of sunlight by keeping their blinds closed during the summer hours at say, 5 o’clock when the sun rose,” Downing said in a 2015 video.

After decades of sporadic use throughout the U.S., the federal government standardized daylight saving time in 1966 with the Uniform Time Act. A measure in the 2005 Energy Policy Act extended it by four weeks per year.

That allowed scientists to finally calculate how much energy it actually saves. In a 2008 analysis presented to Congress, U.S. Department of Energy researchers found the extra time shaved off 0.03% of the country’s annual electricity usage. That’s enough to power approximately 92,000 Texas homes for a year.

These energy savings “generally occurred over a three- to five-hour period in the evening” when people used less during later daylight hours, the report states. But some of that savings was eroded by “small increases in usage during the early-morning hours.”

For decades, the biggest advocate for keeping daylight saving time has been the U.S. Chamber of Commerce, according to Downing. Early on, retail lobbyists realized that “if you give workers daylight when they leave their jobs, they are much more apt to stop and shop on their way home,” he said.

“Daylight saving is a loser as an energy plan, but it’s a fantastic retail spending plan,” Downing said.

Brendan Gibbons

Brendan Gibbons is the San Antonio Report's environment and energy reporter.