Germany became the first country to pass a Daylight Saving Time-style law, as an effort to conserve coal during World War 1.

Benjamin Franklin did not invent daylight saving time. But while living in Paris, he did pen a satirical letter to Parisians suggesting they could save money on lamp oil by changing their sleep schedules. Read it in full here.

Daylight saving time is supposed to help—but does it? Dive into the history, science, and consequences of this biannual aspect of American life (unless you're from Arizona or Hawaii).

Changing clocks twice a year disrupts circadian rhythms, which last an average of 24 hours and 12 minutes. Studies have shown that permanent daylight saving time provides fewer health benefits than standard time.

Messing with the amount of daylight each day has consequences, as America found out in 1974 when it first passed all-year daylight saving time. See why it was revoked less than a year later.

A 2025 study that examined time changes found that permanently changing to standard time would slightly reduce obesity and stroke risk more than switching to permanent daylight saving time.

Daylight saving time can interfere with a person’s sleep schedule, but it also has been linked to increased rates of depression, heart attack, stroke, cancer, and car accidents. UT Southwestern’s Dr. Joseph Takahashi explains why the time change is bad for your brain and health.

In contrast to telling time by physical signs like the sun or stars, cultural time relies on political agreement and standards. The convention of time zones arose due to transportation and communication advancements, and while many work just fine, some are pretty wild. Chief among those is the time zone of the uninhabited Baker and Howland Islands in the central Pacific, which results in a technical 26-hour day.

Printed Advent calendars originated in early-20th-century Germany, where printer Gerhard Lang created the first commercially produced versions. Inspired by his mother’s homemade countdowns, Lang added small doors in the 1920s, establishing the format that spread worldwide.

While most people accept a single seven-to-nine-hour nightly slumber is ideal, the approach is a relatively modern idea. For centuries, interrupted sleep was the norm, with historians uncovering descriptions of two periods of sleep during the normal 24-hour cycle.

Circadian rhythms were first observed in the 1700s, when French astronomer Jean-Jacques D'Ortous de Mairan put a plant in a dark room and watched it still respond to day and night cycles, setting off further studies about specific light-dark biological cycles, an area of inquiry that continues today with the human "clock proteins" at the molecular level.

Astrolabes also provided a person's latitude based on the height of the stars in the sky, thus aiding in navigation. Incense and candle clocks relied on the constant burning rate of fire to track the passage of time based on premarked locations with equal-interval spacing.

Chocolate Advent calendars began in 1958, when German companies first paired the traditional countdown with small pieces of chocolate behind each door. The idea spread slowly at first, but eventually became one of the most popular Advent calendar formats worldwide.

Clocks have revolutionized the way we live, structuring our days into abstract, regular units and providing quantification for those who are chronically late. The alarm clock was the next obvious step: clocks which not only tell you the time but...

On September 1, 1939, Nazi Germany launched a surprise invasion of Poland using blitzkrieg—coordinated air bombardments and armored assaults—to overwhelm Polish defenses within weeks. This lightning-strike strategy shocked the world and signaled both the start of World War II and a revolutionary shift in modern military tactics.

The practice of lighting Christmas trees with electricity didn’t begin until the late 1800s. Before that, families used wax candles on branches—a dangerous tradition that originated in 16th-century Germany.

Advent calendar production resumed in 1946, when German printer Richard Sellmer began issuing nostalgic winter-town designs that became classics, later exporting them to the United States. His company still operates today, producing more than 140 varieties.

While it’s hard to trace the origins of many New Year’s traditions, many of the norms for American New Year’s Eve celebrations come from German immigrants, who significantly influenced American culture in the 1800s. Below is an excerpt from an 1863 New York Times article describing a German New Year’s celebration.

Faced with the 1973 Arab oil embargo, the U.S. responded with bold innovation—enacting a 55 mph speed limit, pioneering daylight saving time, boosting solar research, expanding nuclear power, and pushing energy-efficient building designs and automotive technologies

From gatherings at Stonehenge in the UK to celebrations of the triumph of Mithra in Iran, cultures around the world have marked the shortest day of the year in a variety of ways for a very long time. Here are eight known to us today that endure.

Many of these, such as German Chancellor Otto von Bismarck's 1889 retirement system, emerged decades before America adopted them. This article dives into the modern history of economic security and the key legislation that created Social Security.

Gengenbach turns its 18th-century town hall into a 24-window Advent calendar attracting up to 220,000 visitors each December. Each night reveals new art, reviving winter tourism in the town.

Neolithic Chinese homes faced south for winter sun warmth, while overhangs shielded them from high summer sun. These efforts also influenced urban planning, with cities aligning streets east-west for optimal solar exposure.

Science suggests that early-morning exercise, later-morning peak work or social time, consistent exercise, and a "digital sunset"—starting to turn down the lights in the evening and avoid screens—are important for circadian health.

The movements of astronomical objects, measured in a day and a year, form the foundation of our sense of time. The Egyptians divided each day and night into 12 time eras, using arbitrarily selected stars as references rather than movements of specific celestial objects.

German for "time giver" or "time cues," common external zeitgebers include sunlight, food, and physical activity. The timing of these external influences can shift circadian clocks or lead to irregularities: A 2018 study, for example, found that later light exposure and meals were linked to later timing of peak activity and bedtimes.

Some of history's luminaries worked just four hours a day, including literary great Charles Dickens and biologist Charles Darwin. Observers suggest such a short period forces intense focus sustained by extended rest. In contemporary work, the high premium placed on the number of hours worked can overlook the importance of rest.

For many centuries, during which China was an imperial nation, the lunar/lunisolar calendar (aka the “rural calendar”) was the basis for organizing the year. Several attempts were made over the decades to switch to the Gregorian calendar—which begins Jan. 1—but it wasn’t until the People’s Republic of China was founded in 1949 that it stuck.

In Tuscany, Italy, Prince Piero Ginori-Conti of Trevignano established the plant nine years after creating a generator that powered five light bulbs using steam vents in the area. Within three years, a second plant was built with two generators, each with 10 times the energy output of the first.

In the mid-18th century, the legal system in England operated under the understanding that the New Year began March 25. However, the widespread custom remained a Jan. 1 celebration as the public had been practicing for years. Read along to discover the practical issues this discrepancy caused and how the English legal system ended up yielding to public belief.

England followed the Julian calendar, established by Julius Caesar, which had an inaccurate method of calculating leap years. Because of that, New Year’s Day eventually slipped into the spring and was linked with the Christian festival of the Annunciation, which was on March 25. That date carried over to the American colonies, which didn’t change the first day of the new year until 1752, after England adopted the newer Gregorian calendar.

Celebrating the seasonal change is rarely filled with as much relief and hope around the world as spring. This list compiles some famous and lesser-known springtime traditions from diverse cultures.

Luther lore claims he may have been the first to link tree decorations to Jesus, as he used candles to symbolize the Nativity star. However, German bakers had adorned evergreens with apples and sweets as early as 1419 for Christmas Eve displays.

During World War II, the Nazi regime banned printed Advent calendars because of religious messaging. Officials instead produced state-approved versions featuring swastikas, tanks, and Nazi symbols.

Edison strung electric bulbs outside his laboratory in 1880, and his business partner Edward H. Johnson first wrapped a tree in lights in 1882. It wasn’t until the lights were commercialized in 1917 that they became common in household Christmas decorations.

Time travel has fascinated humans for centuries. It appears in myths, literature, and science fiction. One of the earliest examples comes from the 400 BCE Hindu epic Mahabharata, describing time dilation long before Einstein’s Theory of Relativity. By the 19th century, stories introduced machines enabling time travel—setting the stage for modern sci-fi.

Founded in Germany in February 1920, the National Socialist German Workers’ Party (Nazi Party) attempted its first major power grab in 1923 with the Beer Hall Putsch—a failed coup in Munich that killed about 16 Nazis and four police officers, led to Hitler’s arrest and treason trial, but ultimately elevated his public profile.