Artificial lighting and modern practices like working late are linked with sleep shifts

Studies suggest when you sleep is as important as how much you get

"Molecular clocks" made of timekeeping proteins and genes help regulate the body and its processes, meaning the disruption of one cog will impact another. Those who live in sync with their circadian rhythms report less fatigue, clearer thoughts, greater medication benefits, and better long-term health outcomes.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

The lost medieval habit of 'two sleeps'

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 shift as we age—making older adults want to go to bed earlier

Throughout our lives our internal biological clocks shift. Early-to-rise toddlers become hard-to-wake teens and eventually early-to-sleep seniors. Circadian rhythm fluctuations throughout our life cycle explain some of these changes.

Emulating Earth’s light-dark cycle is important for astronaut health and safety

Astronauts aboard the International Space Station experience 16 daily sunrises, but scientists have learned to try to promote circadian rhythms by phasing through several light settings aboard the ISS to improve astronauts’ sleep and productivity.

Lack of sunlight during Arctic winters can fuel a winter slump and a circadian disconnect

Sunlight typically tells our brain to stop producing melatonin, a hormone that makes us sleepy, but in dark Arctic winters humans must adapt to life without much sunlight. Scientists in this video provide tips that include trying to increase the amount of light around you, even if it’s just table lamps.

'Zeitgebers' like light are external cues for the circadian clock

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.

Humans may have evolved to need less sleep

Humans sleep less than most primates—but more efficiently. Chimps sleep 9.5 hours with 5% in REM, while humans get seven hours with 25% in REM. Some predict we may one day need just five hours, but for now, our sleep patterns balance rest and function, shaped by evolution and environmental stability.

Light pollution is giving oysters insomnia

Oysters, bivalve mollusks that have light-detecting cells along their skin, can't sleep with all this artificial light. According to a 2022 study, oysters' sleep cycles are disturbed by light dimmer than that provided by the full moon. As with humans, it's possible that these bouts of insomnia could have adverse health effects and contribute to the development of disease over time.

Sleep deprivation leads to buildup of danger molecules in the gut

Fruit flies genetically engineered to be awake for as long as they live tend to live half as long as their well-rested brethren. Analysis shows these modified flies suffer from a buildup of DNA-destroying reactive oxygen species in their guts. When enabled to sleep, the flies live as long as their counterparts.

Olympians view sleep as a performance tool, prioritizing routine and environment

Elite athletes emphasize consistent sleep routines, dark and cool environments, the well-placed nap, and tools like eye masks, white noise machines, and supplements like melatonin (particularly for jet lag). This priority belies a core principle: recovery and performance are inseparable. Read more ways Olympians "sleepmaxx" here.

Scientific advances have transformed understanding of Stonehenge’s builders

Techniques such as radiocarbon dating, DNA analysis, and isotopic testing have revised scholars' understanding of Stonehenge. This article presents evidence suggesting that societies were more cooperative and less violent than earlier theories had suggested.

How new research sheds light on why we dream

The theory of where dreams originate began shifting from ancient mystical explanations to modern scientific ones at the beginning of the 20th century. Now, scientists have the ability to track electrical activity in the brain, solidifying some of the field's softer science into observable data and giving rise to sleep labs.

Muslims fasting in Iceland face more than 20 hours of daylight during summer Ramadan

In countries near the Arctic Circle, Ramadan's rule of fasting from sunrise to sunset can cause some unique challenges for the extended periods of daylight in the region. Icelandic Muslims have developed pragmatic workarounds—some follow the hours of Mecca, others adjust locally. It's an edge case that illuminates how a 7th-century practice gets negotiated across radically different geographies.

SAD uniquely affects people with attention-deficit hyperactivity disorder

Those with ADHD—chronic issues with attention and executive function—are primed for SAD. Many are disproportionately evening chronotypes (more awake in the evening), have a delayed sleep phase, and have low sensitivity to light in the morning. This podcast explores the overlap between these two groups.

Modern workplaces were engineered for efficiency, not work-life balance

Modern work organization traces back to 19th-century scientific management, an approach that optimized output by viewing workers as machine components. That logic still persists today and contributes to burnout, stress, and disengagement. Researchers propose a "circular work" model that combines effort with recovery, learning, and renewal, suggesting productivity and well-being should align rather than compete.

The lifestyles of early humans

For 2.5 million years, humans lived on Earth without leaving a written record of their lives—but they left behind other kinds of remains and artifacts.

Visualizing how American men and women spend every hour of the day, by decade of life

Drawing on three years of Census time-use data, the tool tracks 12 activities—sleep, work, housework, caregiving, TV, and more—across age groups from the 20s through 70s. One persistent gap: women spend 45 more minutes per day on housework than men on average.

Some dinosaurs evolved night vision and acute hearing for nocturnal hunting

Paleontologists analyzed the fossilized eye and ear structures of 16 theropods, finding that some had owl-like hearing and huge pupils. These characteristics are consistent with modern-day nocturnal species, including nightjars and geckos.

How did ancient cave painters manage to see what they were doing?

As ancient artists made their way deep into caves and created massive works of art that continue to inspire awe today, they would've required light sources to see what they were doing. This gallery details some of the light sources that cave artists...

Rising sea levels due to climate change may be slowing Earth's rotation

A 2024 PNAS study found that from 2000 to 2020, the length of a day increased at a rate of 1.33 milliseconds per century, an unprecedented amount in the 3.6 million years of day-length changes reconstructed from an analysis of benthic foraminifera fossils. Researchers suggest the slowing comes from changing ice sheets redistributing planetary mass.

Dangers of a record-breaking, sleep-skipping stunt

In 1963, 17-year-old Randy Gardner decided to stay awake for as long as it took to break the current world record. He managed to stay awake for 11 days. In 2017, the then-71-year-old Gardner told NPR that his experience had come back to haunt him as insomnia. The challenge has since been removed from the Guinness Book of World Records due to its dangerous consequences.

Bright light therapy involves basking in 10,000 lux of light for 30 minutes each morning

Nothing is better than going outside and soaking up real sunlight. However, this is harder in winter, especially in very cold and cloudy regions. SAD lamps are designed to project 10,000 lux—a unit of illuminance, or how much light actually hits a surface (rather than how much is produced, like watts). This video discusses product options and practical considerations.

The Aztecs synced their solar calendar with a complex 260-day ritual cycle

Researchers have uncovered how the Aztecs aligned their agricultural solar calendar with a symbolic 260-day ritual calendar, utilizing celestial tracking and monuments. Evidence from ruins and writings explains why their new year corresponded to February 23 on the Gregorian calendar.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

A medieval warm period reshaped agriculture across parts of the world

Between 750 and 1350 CE, some regions experienced temperatures that rivaled or exceeded late-20th-century averages, likely due to shifts in El Niño–La Niña cycles. The warmer, wetter climate in Europe and northeast North America boosted agriculture, while causing droughts elsewhere.

Limited battery life and increasing discomfort prevent extensive use of mixed reality headsets

Spending 24 hours wearing Apple's Vision Pro highlights some of the challenges facing MR technology, which are compounded by an increasing number of bugs when software is run in nonideal conditions. However, practical and entertainment benefits include placing multiple midair timers when cooking and experiencing immersive multimedia, such as astronomical flythroughs.

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

Scientists testing how climate change affects plants found, in a years-long simulation study, that poison ivy grew 70% faster with the resulting extra carbon dioxide.

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

In recent years a child anxiety expert has created and tested a novel phobia and anxiety treatment approach for children, focused on changing how parents respond to the fears.

Watch how algorithms can be designed to train themselves and self-improve without human input, to the point where the optimized code is too complex for programmers to understand.

Planeterrellas create artificial auroras that mimic the atmospheric displays of light by setting up an electric field between two metal balls in a jar filled with a small amount of air.

Stanford built a Google Maps for the Roman Empire, revealing how much it cost to travel in the ancient world

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

Cultural norms about how to handle the bodies of loved ones in communities in West Africa have hampered Ebola responses.

NBA superstar Victor Wembanyama spent the 2025 summer training with monks in central China to enhance his body and mind.

The distributor behind 'Rocky Horror' pulled the film from its scheduled national release, believing it would be a failure, though it eventually amassed a dedicated fanbase through midnight showings, a trend that continues over 50 years later.

A vending machine run with Anthropic's AI went out of business after it was convinced to give away items for free and sell a video game console.

The Brothers Grimm were lawyers before they were storytellers, but became interested in fairy tales as they began investigating how rules and customs had been passed down through cultures.

About 2,000 US babies are born annually without some portion of their limbs, potentially leading to a lifetime of pricey prosthetics.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

A researcher recently discovered an interview from 1967 between groundbreaking journalist Joan Didion and the Grateful Dead, years before the band became an institution.