Fear (and stress) can be contagious via pheromones secreted by the body

Stress can be contagious—and scientists want to learn more about it

Researchers have shown that being around someone who is stressed can trigger a stress response in your body, such as elevated cortisol levels and elevated heart rate. One way this was recently studied was by having people watch stressful activities, like a recorded job interview or solving challenging math problems, and then sampling hormones in observers' spit.

Why does the body have a stress response?

When encountering a stressful situation, the human body typically goes into what is known as "fight-or-flight" mode. Because it evolved as a survival mechanism, the biochemical response enables people and other mammals to react quickly to life-threatening situations. The carefully orchestrated yet near-instantaneous sequence of hormonal changes and physiological responses helps someone to fight the threat off or flee to safety.

Fear has a specific 'smell'—at least to machines

This excerpt from a Mythbusters episode takes on the smell-of-fear question, comparing the sweat composition of individuals exposed to snakes, rats, and scorpions with that of people exercising. Molecularly, the sweats are different to a gas chromatography machine, but to most noses would be indistinguishable.

Fearology, or the study of fear, explores the difference between stress and fear

Our brains involuntarily respond to our environment and signal alarm when that isn’t always needed, triggering responses that include goose bumps. But understanding fear and how to talk our brains into calming down can improve daily life.

Humans are wired to pick up on each other's emotion, making laughter contagious

The reaction plays a key role in establishing interpersonal connections and relieving stress by releasing endorphins—feel-good hormones. A 2021 study identified at least 65 animal species that produce playful sounds, such as laughter.

Stress affects different animals in different, but useful, ways

Animals feel stress when they experience actual dangers—such as a zebra chased by a lion. Humans often feel stress from worries, memories, or even thoughts about problems that may occur in the future. For this reason, animals tend to experience stress in short, intense bursts. Conversely, people can feel stressed for long periods, which can eventually be harmful to their health.

Goose bumps are often triggered by emotions

A physiologist and professor of zoology explains that the subconscious release of adrenaline, a stress hormone, causes a contraction of skin muscles. It’s released in several situations, including when humans are cold, afraid, or feel strong emotions. (Some readers may experience a paywall.)

The hormone that spreads love and helps fish share fear

Scientists consider emotions like fear and empathy to be among the oldest evolutionary behaviors observed in mammals. Yet to date, how these reactions are processed in the brain, regardless of species, is not well understood. A new study reveals how the chemical oxytocin—known as the "love hormone" in humans—helps let fish know when their friends are in danger.

Stress-induced hormones contribute to gray hair

When the body experiences stress, the sympathetic nervous system releases the hormone norepinephrine. This hormone prematurely activates pigment-producing cells (melanocytes) in hair follicles, which depletes the hair's ability to retain color over the long run.

Stress is a response to external triggers, while anxiety is persistent and internal

When distinguishing the two, stress is a reaction to identifiable situations like deadlines or conflicts, and its symptoms fade when the stressor is gone. However, anxiety may jump from one worry to another over time without any apparent cause.

Cold water swimming can induce positive stress

The tradition of cold water swimming (or taking a cold plunge, or even a cold shower) has been shown to release the same hormones triggered during a stress response. This can have the effect of increasing blood flow, improved mental acuity, and more.

Panic attacks are intense fear episodes that often occur without a clear trigger

Unlike typical fear responses to real danger, panic attacks can mimic serious health problems, such as heart attacks. Sweating during a panic attack may seem random, but it's a leftover survival mechanism that made it easier for our ancestors to escape by slipping out of an attacker’s grasp.

Consuming true crime media can increase stress and anxiety

Consuming true crime media can activate one's sympathetic nervous system, which controls the fight-or-flight response. Staying in this heightened state of vigilance can lead to stress-related illnesses, including hypertension, and mental conditions, including depression and anxiety. Additionally, people who actively consume crime news, whether they consider it to be entertainment or educational in nature, report being more fearful of crime, regardless of actual crime rates.

The science of spring fever

Researchers have confirmed what people have sensed for ages: Our emotions during the springtime can go a little wild. This piece breaks down the impact of the seasonal transition on our bodies and prescribes a few ways to mitigate the effects.

Touch deprivation can heighten anxiety and depression

Pacinian Corpuscles are pressure receptors just under the skin that send signals to the vagus nerve in the brain—that's the cranial nerve which regulates involuntary actions like breathing, heart rate, and the general "fight or flight" response. Activating those receptors can slow the heart, decrease blood pressure, and lead to the release of oxytocin and cortisol. The absence of touch, conversely, can promote negative feelings.

Most fungal pathogens can't survive the heat of our bodies

Fungal pathogens typically struggle to survive human body temperatures, but researchers hypothesize that global warming conditions will force fungi to adapt to hotter temperatures, with implications for their ability to also survive within our bodies. That type of evolutionary adaptation would lead to more dire health threats for humans.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

The word allergy is partly derived from the Greek word 'allos' for 'other'

For people with allergies, their immune systems recognize substances as a harmful "other"—cuing an inflammatory response. This podcast explores allergy details and related topics, including how scientists are interested in if the same allergic response mechanisms could underpin other health issues, including severe, painful symptoms around the time of menstrual cycles. Since estrogen acts on white blood cells called mast cells, which leads to the release of histamines—similar to what happens during allergic responses—an understudied question is whether the same process is fueling some of the uncomfortable symptoms around menstruation. An allergist guest notes this raises questions about if antihistamine medications like Pepsid might alleviate them, something that hasn't yet been explored in clinical trials.

Fame can trigger addictive, drug-like highs in the brain

Differences in the type of fame, such as movie stardom, sports, and internet virality, can produce varying degrees of dependence on individuals based on their age and background. Some individuals—particularly children—can develop drug-seeking behavior as they pursue continuous dopamine spikes if they lack an existing sense of fulfillment from elsewhere.

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

There are at least 6 fascinating examples of mind-controlling parasites

Parasitic organisms—including flatworms and barnacles, not just fungi—can modify animal behavior. They can give rise to dancing fish, pulsating snails, suicidal rats, and more. Though some of these pathogens can sicken humans, there is no strong evidence that any can control human behavior.

Major genetic shifts in flu viruses can spark global pandemics

Antigenic shift happens when two different influenza viruses infect the same host and swap genetic material. The result is a brand-new subtype of influenza which, if easily spread among people, can trigger a worldwide pandemic.

Diabetes is a hormonal disorder

Hormones are naturally produced in the body in concert with cell receptors, influencing how cells behave, but diseases that affect hormonal production, including those produced by the pancreas or the thyroid, can upend those processes.

The origin of chaos theory, colloquially known as the 'butterfly effect'

The theory explains that systems following well-understood physical laws can still produce unpredictable outcomes due to small variations in their initial conditions. Originally identified in weather data, elements of chaos have been observed in stock market fluctuations, cardiac arrhythmias, and the evolution of online social movements.

Measles is one of the most contagious preventable diseases

The virus’s ability to persist in the air for up to two hours means an infected person could enter a room, leave, and two hours later infect someone else entering the room. Its location in the body’s upper respiratory tract also makes it easy for viral particles to be sneezed or coughed into the air.

Some female fireflies mimic the signals of other species to lure in and eat them

The genus Photuris does not produce its own defensive pheromones to ward off predators, so it has developed mimicry to attract males of firefly species that do. Unsuspecting males are consumed after these chemicals—lucibufagins—are extracted.

Could all mental health disorders have a unifying 'p-factor'?

Some researchers have argued in the past couple decades that all mental health disorders may have a unifying dimension—a theoretical "p-factor" that is common across mental illness, but life experiences and behaviors influence if and how illness manifests. Proponents point to similarities across different disorders, while detractors argue that such connections are largely exaggerated.

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.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

When a Paris department store hesitated to sell Estée Lauder's perfume, she 'accidentally' broke a bottle, causing the smell to spread throughout the store and shoppers to start asking to buy the scent.

When caught in the mouths of cardinal fish, seed shrimp release glowing, bioluminescent chemicals, which alert predators of the cardinal fish, prompting the shrimp's ejection.

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

Poison ivy can cause rashes year-round since all parts of the plant contain urushiol, the oil that triggers our allergic response.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

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

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

After 25 people used virtual reality headsets to practice flying with virtual wings—flapping their arms—their visual cortex responded to the wings almost as if they were real arms, treating them as body parts.

Existentialist writer Jean-Paul Sartre coined the famous phrase 'Hell is—other people' in his play 'No Exit'

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.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

Fast-casual restaurant Chili's is experiencing a resurgence, with its parent company recently reporting a nearly 32% increase in sales, thanks to passionate Gen Z fans on TikTok.

After her fellow cult members tried to kill her with an LSD-infused hamburger, one member of the Manson Family, the murderous cult led by Charles Manson, decided to testify against the group's leader.