25 Intriguing Facts About Daylight Saving Time

Whether you enjoy the longer daylight hours in summer or dislike the abrupt change in time, daylight saving time is unavoidable (at least in most regions of the United States). Here are 25 things you should be aware of before making the biannual time switch.

1. Benjamin Franklin wasn't entirely serious when he proposed daylight saving time.

More than a century before any major country implemented daylight saving time (DST), Benjamin Franklin proposed a similar idea in a satirical essay. Published in 1784, he argued that:

“The initial discomfort will only last for the first couple of days; after that, the change will feel as natural and easy as the current disorganization [...] Force a man to rise at four in the morning, and he will likely go to bed willingly at eight in the evening; and after eight hours of sleep, he will more readily rise at four the following morning.”

In a remarkably foresighted section, he suggested the plan could save money (though at the time, people were conserving candle wax rather than electricity). To enforce this bold idea, Franklin recommended taxing shutters, rationing candles, banning non-essential nighttime travel, and even firing cannons at sunrise to wake late risers. While his essay touched on some practical points, Franklin might have written it partly to mock the French for their laziness, mentioning that those unaware of the sunlight wasted each morning might be shocked to learn about it. He wrote that they “have never seen any signs of sunshine before noon.”

2. The official credit for the idea of daylight saving time actually belongs to an entomologist.

The initial serious push for DST came from an unlikely source. An entomologist, who worked at a post office by day and hunted insects at night, grew frustrated by how early the sun set during summer. He proposed advancing the clocks to provide more daylight for bug collecting—along with other evening pursuits. The clocks could then be turned back in the winter, when both people and bugs were less likely to be outside.

When the idea was presented to a scientific society in New Zealand in 1895, it was dismissed as impractical and overly complex. Just 20 years later, daylight saving time began to spread across the industrialized world.

3. Germany was the first to make daylight saving time a legal requirement.

In 1916, Germany became the first nation to officially implement daylight saving time. The move was driven by an effort to conserve coal during World War I, and Britain, along with many other European countries, quickly followed Germany's example. It wasn't until 1918 that the U.S. adopted the time change. A year after entering the war, the U.S. began using DST as a measure to conserve electricity. Most nations, including the U.S., discontinued official observance of the time shift after the war.

4. Daylight saving time saw a resurgence in popularity during the energy crisis.

In the 1970s, the U.S. revisited the idea of DST, once again focusing on energy conservation. The oil embargo of 1973 had sparked a nationwide energy crisis, and the government sought ways to reduce public energy consumption. Daylight saving time was implemented at the start of 1974 to conserve energy during the winter months. Not everyone was on board with the change: Some of the most vocal critics were parents, who had to send their children to school before sunrise.

5. Daylight saving time might actually be a drain on energy.

Despite daylight saving time’s origins as an energy-saving measure, research indicates it may actually be counterproductive. A 2008 study in Indiana revealed that the statewide adoption of DST two years earlier led to a 1 percent increase in total energy consumption. While it's true that shifting the clocks can reduce lighting costs, heating and air conditioning expenses tend to rise. That extra hour of daylight is only helpful if people are actually willing to spend time outside to take advantage of it.

6. Daylight saving time could also pose a health risk.

Even if daylight saving time were to lower your energy bills, it wouldn't eliminate the negative effects it can have on human health. Multiple studies suggest the lost hour of sleep when we spring forward can have harmful consequences: an increased risk of heart attack, stroke, vulnerability to illness, and seasonal depression have all been linked to the time shift. Researchers have also found a rise in traffic accidents and workplace injuries related to the transition into daylight saving time.

7. Daylight saving time can reduce crime rates.

Though it's common to gripe about daylight saving time, it's not all negative. One key benefit of the time change is a reduction in crime. A 2015 study found that the start of DST in the spring was linked to a decrease in robberies.

8. Daylight saving time is not a requirement under federal law.

Daylight saving time has been widely adopted across the U.S., but it’s still not mandatory by federal law. Residents who are tired of the time change each year might want to relocate to Arizona. The state doesn’t have much need for additional sunlight, so they skip the time shift every spring. However, this creates a unique situation for the Navajo Nation, which does observe DST. The Navajo Nation is entirely within Arizona, and the smaller Hopi reservation is entirely within the Navajo Nation. While the Hopi follow Arizona's lead and skip DST, the Navajo Nation ends up with a time anomaly, where half the year, it’s an hour ahead of the rest of Arizona.

9. Daylight saving time begins at 2 a.m. for a specific reason.

Daylight saving time doesn’t start exactly at midnight as you might think. Instead, the clocks are adjusted at 2 a.m., when most people are hopefully still asleep. This timing was chosen to avoid disturbing early shift workers and to ensure that bars and restaurants, which have already closed, won’t be affected by the change.

10. The candy industry pushed for a longer daylight saving time period.

Until recently, the candy industry faced a dilemma when daylight saving time ended in the fall. This usually happened on the last Sunday of October, right before Halloween. The industry lobbied for years to delay this shift. In one notable attempt, candy lobbyists placed small candy pumpkins on the chairs of every senator in 1985 to make their case.

In 2005, the National Association of Convenience Stores supported a proposal to extend daylight saving time to eight months. They argued that more daylight would boost candy sales, especially for Halloween trick-or-treaters. The law to extend DST into November was passed and took effect in 2007.

11. Different nations have various names for daylight saving time.

In the UK, when clocks are set forward by one hour, it’s referred to as British Summer Time (BST). When the clocks are set back, the country reverts to Greenwich Mean Time (GMT). Across Europe, different regions observe Western European Summer Time (WEST), Central European Summer Time (CEST), and Eastern European Summer Time (EEST). In Ireland, the standard time is called Irish Standard Time (IST).

12. Daylight saving time wouldn't be beneficial for countries close to the equator.

The main rationale behind daylight saving time—saving energy—seems outdated, as modern concerns have shifted from light bulbs and coal usage to other forms of energy consumption.

The California Energy Commission found that extending daylight saving time by one month in 2007 only resulted in a meager 0.18 percent energy saving. While we may reduce lighting use, the gain is offset by increased air conditioning use during the warmer evening hours. One study of 44 studies revealed a modest 0.34 percent electricity saving during DST, with the most significant savings in locations farther from the equator, while subtropical regions saw an increase in electricity consumption due to DST.

13. The correct term is daylight saving (not savings) time.

For those particular about the details, the correct term is daylight saving time, and it is not capitalized. The U.S. Government Publishing Office Style Manual specifies no plural 's' in the phrase [PDF]. The online Thesaurus clarifies that 'saving' is singular because it refers to saving time, not something like a savings account. However, it also acknowledges that the term 'daylight savings time' is widely used and accepted in casual conversation.

14. For many years, states had the authority to decide whether or not to observe daylight saving time.

The U.S. first adopted daylight saving time in 1918, abandoned it after World War I, and then brought it back in February 1942 during World War II. At that time, President Franklin Roosevelt introduced a year-round DST, known as “War Time.”

Following World War II, states and localities were free to choose whether or not to observe daylight saving time, creating confusion and chaos with time zones from 1945 to 1966. Industries like broadcasting, railroads, airlines, and bus companies struggled to maintain accurate schedules. For example, Iowa had 23 different start and end dates for DST, and St. Paul, Minnesota, began observing DST two weeks earlier than Minneapolis.

In 1966, Congress passed the Uniform Time Act, which required states observing DST to follow a uniform schedule for when it began and ended. The Energy Policy Act of 2005, effective in 2007, extended daylight saving time by a month, starting in March and ending on the first Sunday in November.

15. Less than 40 percent of the global population observes daylight saving time.

As of 2023, daylight saving time is observed in 71 countries. Nations near the equator experience minimal change in daylight throughout the year, so most of them do not adopt DST. For instance, 38 African countries have never implemented it.

Among the countries that do practice daylight saving time, many have alternated between adopting and abandoning it. Canada holds the record for the longest use of DST, with 111 years, while the United States has observed it for 106 years.

16. There is growing support for the idea of observing daylight saving time year-round.

The push to make daylight saving time permanent has gained momentum in recent years. In 2018, Florida made an attempt to establish year-round daylight saving time by passing the Sunshine Protection Act in its House and Senate. Since then, several other states have joined the effort.

States, however, cannot implement year-round daylight saving time on their own, as the federal Uniform Time Act mandates a synchronized schedule—meaning all participating states must adhere to the same start and end dates. As a result, state legislation can only request an exemption from the Uniform Time Act from the federal government.

In March 2021, a bipartisan group of U.S. senators co-sponsored the Sunshine Protection Act of 2021, a bill that would make daylight saving time permanent (currently, what is considered 'standard time' only lasts from November to March). The Senate approved the bill in 2022, and as of 2023, it still awaits approval from the House and the President.

17. Contrary to popular belief, most farmers actually oppose daylight saving time.

A widespread myth suggests daylight saving time was introduced to benefit farmers, but in reality, it was quite the opposite: farmers have long opposed the shift. The change disrupts their routines, forcing them to rush crops to market. Regardless of the clock, they still need to wait for the morning dew to evaporate off the hay. For dairy farmers, the time shift also confuses the cows and complicates the scheduling of their workers.

18. Department stores are big fans of daylight saving time.

While farmers were busy lobbying against daylight saving time, chambers of commerce and business leaders were backing it. Lincoln Filene, the department store mogul who founded Filene’s Basement, advocated strongly for DST and even created promotional campaigns that suggested the time change would be beneficial for farmers.

In 1986, while pushing for an extension of daylight saving time from six to seven months, the grill and charcoal industries reported a $200 million boost in sales thanks to an extra month of daylight saving time.

19. The duration of daylight saving time continues to increase.

Congress has lengthened daylight saving time three times: first with a temporary extension during the energy crisis of the early 1970s, again in the 1980s, and once more in 2007. It now lasts for eight months, while standard time only covers four.

20. Pets are aware of the changes in their humans' routines during daylight saving time.

Pets thrive on predictable routines, and nothing matters more to them than mealtimes and playtime. So when a pet's consistent feeding schedule gets disrupted—like when their owner wakes up an hour later, pushing back breakfast—they notice the change. Experts suggest a gradual adjustment, much like what benefits humans. This could involve shifting their feeding times by 10 or 15 minutes before the actual time change.

21. Daylight saving time comes with a hefty price tag for airlines and other transportation methods.

When daylight saving time was extended by a month in 2007, the airline industry voiced opposition. The Air Transport Association estimated that adjusting flight schedules to match international routes would cost the industry $147 million. Trains also face challenges, with Amtrak either recovering lost time in the spring or delaying an hour in the fall.

22. The Network Time Protocol enables devices like cell phones to automatically adjust to daylight saving time.

In the not-so-distant future, it may feel old-fashioned to manually turn clock hands forward or backward or reset digital clocks on appliances like microwaves or ovens to account for the time change. Thanks to the Network Time Protocol (NTP), devices like cell phones, laptops, and others update automatically. This protocol synchronizes the clocks within computer networks.

Connected devices such as cell phones and laptops receive time updates from a server that has obtained precise time from an atomic clock or another reliable source. These networks synchronize to universal coordinated time (UTC) within milliseconds. Since our devices are constantly in communication with cell towers and servers, they automatically adjust for the time change when it happens.

23. For many years, different regions of Indiana followed daylight saving time while others chose not to.

In April 2006, Indiana became the 48th state to adopt daylight saving time statewide. The state has had a complex history with time zones; it was part of the Central Time Zone until 1961, when the Interstate Commerce Commission moved the boundary west, splitting the state into two time zones: Central and Eastern.

Five years later, the U.S. Department of Transportation took charge of time zone boundaries and shifted them again. Most of Indiana moved to Eastern Standard Time, while areas like Gary and Evansville remained on Central Time and observed daylight saving time in the summer. This change was made official when President Nixon signed it into law in 1972.

In 2004, Indiana Governor Mitch Daniels campaigned for the state to observe daylight saving time. After much debate and several votes, the state legislature passed the law in 2005 with a narrow 51-49 vote.

24. Some believe that daylight saving time played a role in the decline of drive-in movie theaters.

At the peak of their popularity in the mid-1960s, over 4000 drive-in theaters could be found across the U.S. Theater owners united in 1966 to oppose the widespread implementation of daylight saving time, arguing that later movie start times would hurt business. Today, only about 330 drive-ins remain, and some enthusiasts blame the time change for their decline.

25. A study showed that most people lose 40 minutes of sleep when daylight saving time begins.

Christopher Barnes, an assistant professor of management and organization at the University of Washington, discovered that the time change in spring typically causes people to lose around 40 minutes of sleep, enough to disrupt our body’s circadian rhythms. Since recovery takes several days, the immediate effects are often most noticeable on the Monday after the shift. Barnes also found a significant rise in “cyberloafing,” or browsing the internet during work hours, on that Monday following the spring time change.