Skin wounds and burns heal fastest if they occur during the day

Humanity's reduced body hair slows down wound healing

Cuts to human skin take twice as long to heal compared to chimps and other mammals. Scientists argue this is due to the reduced number of hair follicles on human bodies. Hair follicles contain stem cells which help repair skin cells faster, so as humanity shed its hair over time, so to speak, it also slowed its wound healing.

Heart attacks are less harmful at night

When heart attacks occur during the day they typically do more harm to the heart tissue than if they occur at night. A 2025 study suggests that daytime heart attacks have higher levels of immune cells called neutrophils to contend with and they appear to worsen the injury. Scientists confirmed this same pattern in experiments with mice. (Some readers may experience a paywall.)

Firework or sparkler burns, even if they cover a relatively small area of skin, can significantly affect our range of motion.

World records are often broken later in the day—and scientists wonder if muscle clocks explain the difference

For reasons that are still not entirely clear, on average, people tend to lift more weight and achieve other exercise feats later in the day. Theories to explain this discrepancy include muscle clocks are at peak performance in the afternoon and that there's morning-to-afternoon variation in core body temperature, hormones, and neural activity.

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

Antiperspirants work better if they are applied at night

Dermatologists recommend applying antiperspirant at night for the best results. When applied to clean, dry skin at night, the active ingredient in most antiperspirants (aluminum salt), combined with the skin's natural moisture, forms plugs that block sweat glands, limiting sweat and related odors.

Laser skin treatments can promote the production of collagen

Skin resurfacing vaporizes the top layer of skin to reveal healthier, new skin, while collagen can give the skin structure and elasticity. Such procedures treat scars and burns, but may leave light spots on the skin.

Why Friday surgeries are (likely) riskier

Scheduling surgery on a Friday may lead to more complications—up to 5% more often—compared to surgeries performed after the weekend. The research was conducted by a team from the United States and Canada and analyzed data from over 450,000 patients who underwent common surgeries in Ontario between 2007 and 2019. Check out their findings here.

See images of medical cases of firework injuries shared on this 'Instagram for doctors'

Included photos include scans of missing or damaged digits, a chunk of missing flesh, a facial injury from a homemade firework in a glass bottle that exploded in the patient's hand before it was thrown, and an injury where a patient's finger bone flew into someone's leg.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak annually

If someone is exposed to one of these plants for the first time, it can take several weeks to develop a rash.

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

An analysis of five adults participating in a German reality program that tasked them with living in a Stone-Age-like settlement for 2.5 months, provided some insights into how modern conditions may have shifted our circadian rhythms. The participants slept about 90 minutes more under these conditions, and went to bed earlier and rose earlier, raising questions about how circadian rhythms, sleep, and sleep quality are affected by modern lifestyles.

Being struck by lightning has a mortality rate of about 10%

Near-immediate deaths are the result of electrical disruptions in the heart and nervous system, causing cardiac arrest, but severe skin burns, temporary paralysis, and blown eardrums are more common. About 74% of survivors are left with a long-term disability, which includes brain damage and changes in memory and mood.

Wind chill speeds up the loss of heat from the body

During cold weather conditions, strong winds against exposed skin can produce a sensation of temperature colder than the surrounding air temperature. The accelerated loss of body heat increases the risk of frostbite and hypothermia, with frostbite able to set in as quickly as five minutes.

Cold-blooded reptiles seek heat, and that behavior may help combat fungal infections

This Radiolab podcast episode takes on the idea that though our human bodies are too warm for the majority of fungal species to effectively replicate inside our bodies, that's not the case for reptiles. Yet when those species warm their bodies by basking in the sun on rocks, they can soak up heat and may also help keep fungal infections in check.

Self-care can't fix burnout on its own

Steps such as exercise, breathing, mindful eating, and spending time with friends, can help alleviate the fight-or-flight mode response of the body to alleviate stress, but they don't fix the stressors causing the burnout. To address those, workplaces may need to consider how to better manage workloads and duties.

Surgery before the dawn of anesthesia

The arc toward anesthetics was painfully slow, with early pain mitigation offerings ranging from analgesics—drugs that dim pain but don't block it—and numbing surgical sites with cold water to gassing patients with carbon dioxide or bashing or bleeding them unconscious. Such treatments and the torturous surgery they preceded led many to avoid even life-saving procedures, and those who survived often kept silent about the trauma.

Robert Louis Stevenson wrote ‘The Strange Case of Dr. Jekyll and Mr. Hyde’ in three days, then burned it

Stevenson woke from a dream and instantly got to writing the “fine bogey tale” he’d witnessed in his sleep. He finished a draft three days later and read it to his wife, who suggested it needed revising. Stevenson eventually agreed and threw the manuscript into the fireplace. He got back to work and emerged three more days later with another draft.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak each year.

Organ donation isn't usually logistically possible if you die at home

Since organs need to be well-preserved for organ donation, with oxygen flowing through the body, internal organs often aren't viable for organ donation if someone dies at home. But some tissues—like eye corneas and skin tissue—may still be donated since they remain usable for a longer period without oxygen flow.

The average cell's DNA is damaged thousands of times daily

In the case of radiation-induced distortions in a DNA strand, specialized proteins can cut out entire segments and rebuild them using the second strand as a complementary template. If both DNA strands are completely severed, proteins interlace undamaged DNA with the severed DNA and rebuild both using complementary base pairing.

Ticks must typically be attached to a person for more than 24 hours to transmit Lyme

Infected blacklegged ticks must typically be attached to a person for more than 24 hours—and often closer to 36—to transmit Lyme. That period is enough time for the bacteria that causes Lyme to migrate from the tick's gut into the person's bloodstream while it's latched on through its bite. (There are rare documented cases of transmission under 24 hours.) Rapid removal of the tick is key to disease prevention.

White patients waited 374 days for a kidney—Black patients waited 727 days

A 2022 congressionally mandated report highlighted racial inequities in the US organ transplant system, including disparities that made it more likely white people will be placed on organ wait lists than Black people. It spotlighted inequities such as racial differences in median kidney wait times identified in earlier research. The report, from the National Academies of Sciences, Engineering, and Medicine, recommended fixes including that the Department of Health and Human Services develop national performance goals for the system and achieve equity in the system in the next five years.

Stem cell therapies show promise in treating spinal injuries

Researchers have long hoped to use stem cells in regenerative medicine to help patients with spinal cord injuries restore sensation and movement. A 2024 clinical trial illustrates how stem cells derived from patients' fat tissue could help spur the creation of new cells in the spinal cord.

Autoimmunity is when the body attacks itself, causing inflammation

Inflammation is the body's way of healing itself, and acute inflammation saves our lives when we have injuries or infections. It increases blood flow to the affected areas to bring immune cells to fight off invaders. This often results in short-term swelling, redness, and pain.

What do vitamins actually do?

Vitamins are molecular tools the body needs to carry out regular cellular processes, such as wound healing. This 45-minute video dives into the science behind vitamins and their role in the body. There are 13 essential vitamins that must be...

The benefits of lucid dreaming

Lucid dreams happen when the dreamer knows they've stepped out of the bounds of waking life. Studies show it can help dreamers cultivate creativity, process grief, and work through trauma. A 2021 study found that 85% of participants with PTSD no longer qualified for the diagnosis after a week of trauma-informed lucid dreaming in which they intentionally witnessed (and therefore integrated) recurring nightmares or changed the outcome completely.

Watch a time-lapse of hard coral growth, which forms coral reefs

Over several weeks in an aquarium, these staghorn coral polyps grew and produced new polyps as they deposited calcium carbonate, which forms the basis of coral reefs. At the 0:28 mark, you can see coral growth healing a damaged branch.

Tattoos remain visible on your skin thanks to immune cells called macrophages

Why the sun's equator rotates once every 24.5 days, but the poles take over 34 days

Just like the Earth, linear speeds on the surface of the sun decrease from the equator to the poles. However, rotation time also appears to vary with depth, with the radiative zone beneath the convection zone rotating about once every 26.6 days. Measurement uncertainty has prevented measurement of the rotation of the solar core.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

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

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.

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

Before writing 'Walden,' transcendentalist Henry David Thoreau nearly burned down his hometown with a campfire that grew out of control.

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.

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

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in casualties, forces mobilized, and displacement of civilians.

Explore the archaeological treasures of Pompeii, the city buried under volcanic ash when Mount Vesuvius erupted in 79 CE.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

See the most iconic photos from four decades of LIFE magazine

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