Reduced inflammation from cold plunges lacks scientific support

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.

Some data shows cold showers can help with depression

An icy water exposure can lead to the release of norepinephrine, cortisol, dopamine, and other stress hormones that are beneficial, among other potential effects. Some data shows that this type of exposure can help combat depression symptoms among some patients, but more research is still needed. (Some users may encounter a paywall.)

Heatstroke treatment guidelines were built almost exclusively on research in men

Protocols for the standard treatment recommendation for heatstroke—whole-body cold water immersion—were built based on studies almost entirely in men. The research wasn't replicated in women, who typically cool faster than men during cold water immersion, raising questions about standard protocol safety for women, due to the risk of overcooling.

Health workers may cool body temperatures with convection cooling

That's spraying a patient with water and putting fans over them. Cooling the body by removing clothing and placing cold water and ice packs—and not blocking evaporation—are essential cooling steps.

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.

How water pressure affects the body

The extreme conditions of the deep sea include increasing amounts of pressure as explorers and organisms descend into its depths. The major danger for both fish and humans is the way pressure changes how body tissues absorb chemical molecules...

How to survive hypothermia

Hypothermia is a deadly risk for those living in cold areas, causing around 1,500 deaths a year in the United States. Stay safe with tips from this article, which cites research papers to help prevent and treat the condition. Take note of the best fabric to wear when cold weather hits—not cotton but wool.

Heat-related complications are of greater concern for distance runners than cardiac threats

Analysis of more than 130,000 runners in Tel Aviv events during a seven-year period indicated that the runners were 10 times more likely to experience heatstroke than serious cardiac problems. Scientists suggest that runners should take 10 to 14 days to acclimate to a hot climate before tackling a serious run.

Certain medications that affect blood flow or mood boost the risk of heatstroke

Drugs that narrow blood vessels, beta blockers that regulate blood pressure, diuretics, antidepressants, and antipsychotics can all affect the body's ability to regulate its internal body temperature, and so individuals taking these medications need to take special care in extreme heat and when exercising in hot conditions.

Bears may have evolved natural mechanisms to prevent blood clots during hibernation, an important development, since inactivity typically leads to blood clots in other animals.

Why hibernating bears don't get blood clots

For mammals, long periods of inactivity can lead to health problems—blood flow slows and pools, veins kink and distort, and clots potentially form. Hibernation takes this risk to the extreme, yet for decades why animals like bears did not exhibit...

Some research suggests that the gut microbiome influences our risk of heatstroke, with elevated exercise levels raising body temperature to unsafe levels and increasing gut permeability—causing a "leaky" gut.

Heatstroke occurs when the body reaches 104°F or higher and can't cool itself

Untreated, this medical emergency can result in permanent disability or death. Someone suffering from heatstroke—defined as a core temperature of 104 degrees Fahrenheit but sometimes as high as 106 degrees Fahrenheit—may appear confused and require immediate cooling, ideally with an ice bath.

Korey Stringer, of the Minnesota Vikings, died of heat-related illness in 2001

In response, the NFL overhauled its heat approach and no other player has since died from heat-related illness. Even at the high school level, research suggests safety measures should include: mandating water breaks, keeping a cool tub available, and having athletes acclimate to high-temperature playing conditions for a week or longer before donning the full set of protective equipment.

Surfer's ear, from repeated cold water exposure, leads to new bony protrusions in the ear

Frequent exposure to icy cold water, typical in surfing, can cause tiny bony growths to develop in the ear canal, informally called surfer's ear. While the exact cause for these growths is unknown, it may be the body's protective response to shield the ear drum from the cold. These protrusions can heighten the risk of swimmer's ear, lead to wax buildup, and result in hearing loss.

Michael Phelps used cupping at the 2016 Olympics, a traditional Chinese medicine approach thought to bring blood to the skin to boost muscle recovery.

Why do you shiver when cold?

Humans are warm-blooded creatures, so our bodies like to maintain internal temperatures separate from and typically above those in their environment. This is made possible by a process known as thermoregulation. When the brain's hypothalamus senses a drop in the body's core temperature, skeletal muscles may be ordered to shiver, sending out waves of muscle contractions and exothermic biochemical reactions whose byproduct includes heat and energy.

A history of treating frostbite

Amid Napoleon's invasion of bitterly cold Russia, soldiers succumbed to frostbite by the thousands. Nineteenth century doctors recommended walking and rubbing snow around the affected area. Fast forward to recent years, and the FDA has approved its first ever drug to treat frostbite. Listen to this podcast to learn the history of this wintry affliction.

If the temperature of water continuously decreases but it is not given room to expand, it will eventually contract and form exotic forms of ice that sink in liquid water.

Supplements ahead of exertional heatstroke helped protect mice against brain damage

In the lab, mice dosed with probiotics prior to inducing exertional heatstroke, had better cognitive outcomes. This evidence underscores the links between the gut microbiome and the brain, at least in rodents.

Bath bombs can produce endothermic reactions that cool water

In bath bombs containing citric acid and sodium bicarbonate, water facilitates the reaction between the bicarbonate and acid, providing energy as the salt dissolves. The loss of energy in the water reduces the average speed of the water molecules, reducing the temperature of the bath.

Heatstroke is when the body's core temperature becomes dangerously high—and needs to cool

Warning signs that the body is overheating include rapid breathing, cramps, heavy sweating, nausea, and feeling lightheaded. Drinking plenty of fluids, seeking shade, and cooling the body down as quickly as possible with icepacks can help reduce the risk of heatstroke.

We can get food poisoning from spending time in swimming pools, lakes, rivers, and ponds

Some of the same pathogens that may sicken us in food or water may also sicken us in recreational swimming environments. Bacteria can rub off of people’s (or animal’s) bodies or contaminate the water through a diarrheal episode. Washing your hands for at least 20 seconds before eating food if you are at the beach, pool, or other similar environments and being sure not to swallow the water are ways to help keep safe.

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.

Laundry detergents designed for cold-water washes rely on proteins isolated from microorganisms native to cold climates, such as Iceland.

How specialized oxygen mixtures like heliox enable deep diving without feeling drunk

Beyond a depth of about 30 meters (98 feet), if divers are breathing surface air, which is about 78% nitrogen, underwater pressure forces more nitrogen into the bloodstream and induces nitrogen narcosis, whose symptoms resemble alcohol intoxication. Through saturation diving, where nitrogen is replaced with helium—an inert gas—deep divers can maintain cognitive function while working for extended periods.

Heatstroke can reprogram your DNA, putting survivors at risk of future health problems.

Some claim breathwork can improve mental health, help process trauma, and more

Research shows people who practice breathing exercises see a decrease in depression and stress levels, and that such exercises are about as effective at treating PTSD as conventional approaches. Even something as simple as extending exhales can slow one's heart rate and activate the parasympathetic nervous system.

Exertional heatstroke is a leading cause of death among athletes and soldiers in training, and typically occurs when someone sweats intensely while exercising in the heat.

Heatstroke—from overexertion or extreme heat—drives core body temperature to 104 degrees Fahrenheit or higher, setting off a cascade of problems in the body.

Listen to why extensive ear rinsing can create problems

The clinician who hosts this podcast discusses how his patient developed swimmer's ear after he flooded his ears with water during his daily showers, ostensibly to clean them. The resulting itchy, painful ears were the result of removing protective earwax in the ear and also altering the typical pH of the ear.

Heatstroke is sometimes missed because the patient is really sweaty

Since the condition involves losing the ability to cool oneself, clinicians sometimes see someone who has exertional heatstroke—like a high school athlete who is really sweaty—and don't realize the heat-related illness has already progressed to heatstroke. Classic heatstroke typically occurs among the very young or the elderly. (Some users may encounter a paywall.)

Red light therapy—a treatment harnessing a specific form of energy that penetrates the top layers of skin—is marketed for skincare and wellness, but has its roots in NASA plant growth research.

Extreme heat puts people at risk of developing kidney stones

It's essential to remain hydrated in summer weather to keep your body healthy, but one reason is to help dilute minerals that naturally build up if they aren't excreted in our water-fueled urine. Doctors recommend people generally drink 64 ounces of water a day and also eat foods with salt to help ward off dehydration.

Researchers have investigated the benefits of extreme pain rituals, exploring how and why we engage in these events when humans generally naturally avoid pain and perceive it as a negative experience.

Watch a server submerged in a fluid continue to run and stay cool by boiling the liquid away.

Can coral live in cold water?

Dive deep beyond the sunlit coral reefs, and you'll discover a world of deep-sea corals. This article from the National Oceanic and Atmospheric Administration (NOAA) explores the ecosystems of deep-sea corals found way below the water's surface....

Batteries are likely to stop working sooner in cold temperatures

The electrolyte separating the cathode and anode of a battery can thicken, impeding ion flow. Lower temperatures also slow the rate of chemical reactions, further reducing battery capacity. Large draws of power, such as when using heaters, heated seats, etc., in a car during winter, exacerbate battery drain further.

Ear infections can arise from chlorinated water, too

Any water remaining in the ear can lead to swimmer's ear. Chlorinated water, however, can also strip the skin of the oils and wax that would otherwise protect the ear.

High-powered red light therapy—delivered directly to nerve fibers via a fiber optic needle—has been used in recent experimental research to suppress pain.

Extreme temperature resilience appears to be temporary for tardigrades

Although often considered indestructible, scientists observed these creatures could endure temperatures near 150°C for only a few minutes in their tun state. Outside this state, only half the samples in a Danish study survived 37.1 degrees Celsius (98 degrees Fahrenheit) for 24 hours, making tardigrades extremotolerant rather than extremophiles.

Watch how to safely remove water from your ears without increasing your risk of infection.

Can humans delay or reverse old age?

We're not sure yet. Researchers at the University of California San Francisco are studying why some conditions and behaviors, such as low-oxygen environments and exercise, benefit the aging process, hoping to reveal potential health applications. Some of this research focuses on klotho, a naturally occurring age-regulating hormone named after the Greek Fate Clotho. Animal studies on klotho brain injections found subjects had improved memory recall and age-related degeneration resistance.

Short-term cortisol spikes can boost the immune system

Elevated acute levels can enhance the immune system's ability to fight off infection or respond to injury. Chronic heightened cortisol levels, however, can lead to inflammation that harms cells and tissues over time.

This 1440 Original video dives into what the science says about phototherapy and its various potential applications.

13 unconventional ways to stay cool during heat waves

While air conditioning is the default solution for many in a heat wave, it can get expensive while requiring the consumption of fossil fuel energy. So, how else can you stay cool during a heat wave? This list compiles some practical, at times quirky, suggestions, including an ice-pack-filled aubergine hat.

To survive underwater hibernation, some freshwater turtles perform cloacal breathing—blood vessels absorb dissolved oxygen from water drawn into the organism's cloaca, or rear orifice.

Over 200 known species hibernate, allowing them to lie dormant and survive harsh periods when water and food become scarce, such as frigid winter months or scorching summer periods.

An overview of extremophiles and the biochemical adaptations employed by various types

These organisms thrive in environments that would normally be inhospitable to most living things by using molecules that help counter deadly environmental factors. These include antifreeze-like proteins that prevent psychrophiles from freezing and rupturing in polar regions, and osmoprotectants that prevent some extremophiles from losing water to salty environments.

Humans have used geothermal resources for thousands of years

In North America, Indigenous peoples viewed hot springs as sacred places and used them for medicinal purposes, cooking, and surviving cold weather. The ancient Greeks and Romans also viewed them as sacred, partaking in hot mineral baths to relieve ailments and using them for space heating.