From the aroma of fresh-cut grass to the smell of a loved one, you encounter scents in every part of your life. Not only are you constantly surrounded by odor, you’re also producing it. And it is so distinctive that it can be used to tell you apart from everyone around you.

Your scent is a complex product influenced by many factors, including your genetics. Researchers believe that a particular group of genes, the major histocompatibility complex^[1], play a large role in scent production. These genes are involved in the body’s immune response and are believed to influence body odor by encoding the production of specific proteins and chemicals.

But your scent isn’t fixed once your body produces it. As sweat, oils and other secretions make it to the surface of your skin, microbes break down and transform^[2] these compounds, changing and adding to the odors that make up your scent. This scent medley emanates from your body and settles into the environments around you. And it can be used to track, locate or identify a particular person, as well as distinguish between healthy and unhealthy people.

We are^[3] researchers who^[4] specialize in^[5] studying human scent through the detection and characterization of gaseous chemicals called volatile organic compounds^[6]. These gases can relay an abundance of information for both forensic researchers and health care providers.

Science of body odor

When you are near another person, you can feel their body heat without touching them. You may even be able to smell them without getting very close. The natural warmth of the human body creates a temperature differential with the air around it. You warm up the air nearest to you, while air that’s farther away remains cool, creating warm currents of air^[7] that surround your body.

Researchers believe that this plume of air helps disperse your scent by pushing the millions of skin cells you shed over the course of a day off your body and into the environment. These skin cells act as boats or rafts^[8] carrying glandular secretions and your resident microbes – a combination of ingredients that emit your scent – and depositing them in your surroundings.

Your scent is composed of the volatile organic compounds present in the gases emitted from your skin^[9]. These gases are the combination of sweat, oils and trace elements exuded from the glands in your skin. The primary components of your odor depend on internal factors such as your race, ethnicity, biological sex and other traits. Secondary components waver based on factors like stress, diet and illness. And tertiary components from external sources like perfumes and soaps build on top of your distinguishable odor profile.

Identity of scent

With so many factors influencing the scent of any given person, your body odor can be used as an identifying feature. Scent detection canines^[10] searching for a suspect can look past all the other odors they encounter to follow a scent trail left behind by the person they are pursuing. This practice relies on the assumption that each person’s scent is distinct enough that it can be distinguished from other people’s.

Researchers have been studying the discriminating potential of human scent for over three decades. A 1988 experiment demonstrated that a dog could distinguish identical twins living apart^[11] and exposed to different environmental conditions by their scent alone. This is a feat that could not be accomplished using DNA evidence, as identical twins share the same genetic code.

The field of human scent analysis has expanded over the years to further study the composition of human scent and how it can be used as a form of forensic evidence. Researchers have seen differences in human odor composition that can be classified based on sex, gender, race and ethnicity. Our research team’s 2017 study of 105 participants found that specific combinations^[12] of 15 volatile organic compounds collected from people’s hands could distinguish between race and ethnicity with an accuracy of 72% for whites, 82% for East Asians and 67% for Hispanics. Based on a combination of 13 compounds, participants could be distinguished as male or female with an overall 80% accuracy.

Researchers are also producing models to predict the characteristics of a person based on their scent. From a sample pool of 30 women and 30 men, our team built a machine learning model^[13] that could predict a person’s biological sex with 96% accuracy based on hand odor.

Scent of health

Odor research continues to provide insights into illnesses. Well-known examples of using scent in medical assessments include seizure and diabetic alert canines^[14]. These dogs can give their handlers time to prepare for an impending seizure or notify them when they need to adjust their blood glucose levels.

While these canines often work with a single patient known to have a condition that requires close monitoring, medical detection dogs can also indicate whether someone is ill. For example, researchers have shown that dogs can be trained to detect cancer^[15] in people. Canines have also been trained to detect COVID-19 infections^[16] at a 90% accuracy rate.

Similarly, our research team found that a laboratory analysis of hand odor samples^[17] could discriminate between people who are COVID-19 positive or negative with 75% accuracy.

Forensics of scent

Human scent offers a noninvasive method to collect samples. While direct contact with a surface like touching a doorknob or wearing a sweater provides a clear route for your scent to transfer to that surface, simply standing still will also transfer your odor into the surrounding area.

Although human scent has the potential to be a critical form of forensic evidence, it is still a developing field. Imagine a law enforcement officer collecting a scent sample from a crime scene in hopes that it may match with a suspect.

Further research into human scent analysis can help fill the gaps in our understanding of the individuality of human scent and how to apply this information in forensic and biomedical labs.

Uncommon Courses^[1] is an occasional series from The Conversation U.S. highlighting unconventional approaches to teaching. Title of course:Art & Science from Aristotle to InstagramWhat prompted the idea for the course?The idea for this course came out of my own research on intersections between art and science in the early modern period^[2], roughly 1400-1700. In this time, the division between the arts and sciences was not as stark as people perceive it to be today. Many natural philosophers – the scientists of their day – like Galileo Galilei^[3] made images in the process of conducting their studies. However, they also relied on artists and artisans to communicate their ideas to a wider audience – they needed engravers, draftsmen and other graphic arts practitioners to make the images that would go into their books and published works.In addition, throughout history the development of new technologies has affected artistic practices. The invention of the printing press and new photographic technologies allowed scientific ideas to be communicated in new ways to new audiences, but these inventions simultaneously created new artistic media. What does the course explore?In contemporary society, art and science are often characterized as diametrically opposed. However, knowledge making has been inextricably linked to image making since antiquity.

This image, made by Maria Sibylla Merian in 1705, is both a naturalist’s documentation and a work of art. Maria Sibylla Merian via Minneapolis Institute of Art^[4] One way we explore this relationship is by studying people from antiquity to the present who cross these realms. Leonardo da Vinci is a great example. People think of him as a master Renaissance painter, and he painted what is widely considered the most famous painting in the world, the Mona Lisa^[5]. But at the same time, he also pursued scientific questions about anatomy^[6], botany^[7] and motion^[8] and was an inventor^[9].But there were other examples of people who pursued science and art together. In the 19th century, Anna Atkins^[10] was one of the first people to use an early photographic technique – the cyanotype – to study British plants and algae. The images she created^[11] are aesthetically beautiful but also created new knowledge within botany.In the course, we also explore different technological developments that affected the arts, creating new materials and media. These include technologies such as the printing press^[12], camera obscura^[13], daguerreotype^[14] and digital art^[15].Why is this course relevant now?We live in a visually saturated world, yet we often take in these images uncritically. My students encounter images in every aspect of their lives, in greater quantity and at a greater rate than ever before. Yet, people frequently accept these images as true depictions of reality, even when they are not.Why do people assume a scientific image is divorced from the same aesthetic choices and manipulation that are applied to the image on a magazine cover? Why do people accept a scientific image as objective and not a created object like a painting? Issues like photoshopped images or AI-generated artworks may seem unique to the modern moment, but concerns about manipulation and deception have a long history. What’s a critical lesson from the course?Today, the perceived division between empirical and quantitative science and creative and qualitative arts is even more pronounced than in the past. In my classes, I find science students often think that a scientific image made today is strictly true or objective. Yet during the course they discover that many choices get made in constructing that image. What information should be included? What information should be left out? The art students in the class soon come to realize that many of the artistic materials and media they rely on, be it synthetic pigment or digital technologies, were developed for scientific or engineering purposes. What materials does the course feature?“The Republic^[16]” (fourth century BCE) by Plato, where we consider his skepticism of the arts due to their ability to deceive. “De Humani Corporis Fabrica^[17]” (1543) by Andrea Vesalius, an important book on human anatomy where the illustrations and text were equally influential. Images from the Hubble Space Telescope^[18], and how they can be considered both works of art and science. What will the course prepare students to do?It is my hope that after taking this course, students will have gained the skills to be more discerning in how they think about the ways the visual information around them is created. They will not only have a greater appreciation for the processes of creating artistic and scientific knowledge but also have gained a critical lens for assessing the images they see around them.

When 17 people^[1] were in orbit around the Earth all at the same time on May 30, 2023, it set a record. With NASA and other federal space agencies planning more manned missions and commercial companies bringing people to space, opportunities for human space travel are rapidly expanding.

However, traveling to space poses risks to the human body. Since NASA wants to send a manned mission to Mars^[2] in the 2030s, scientists need to find solutions for these hazards sooner rather than later.

As a kinesiologist who works with astronauts, I’ve spent years studying the effects^[3] space can have on the body and brain. I’m also involved in a NASA project that aims to mitigate the health hazards^[4] that participants of a future mission to Mars might face.

Space radiation

The Earth has a protective shield called a magnetosphere^[5], which is the area of space around a planet that is controlled by its magnetic field^[6]. This shield filters out cosmic radiation^[7]. However, astronauts traveling farther than the International Space Station will face continuous exposure to this radiation – equivalent to between 150 and 6,000 chest X-rays^[8].

This radiation can harm the nervous and cardiovascular systems^[9] including heart and arteries^[10], leading to cardiovascular disease. In addition, it can make the blood-brain barrier leak^[11]. This can expose the brain to chemicals and proteins that are harmful to it – compounds that are safe in the blood but toxic to the brain.

NASA is developing technology that can shield travelers on a Mars mission from radiation by building deflecting materials such as Kevlar and polyethylene into space vehicles and spacesuits^[12]. Certain diets and supplements such as enterade^[13] may also minimize the effects of radiation. Supplements like this, also used in cancer patients on Earth during radiation therapy, can alleviate gastrointestinal side effects of radiation exposure.

Gravitational changes

Astronauts have to exercise in space to minimize the muscle loss they’ll face after a long mission. Missions that go as far as Mars will have to make sure astronauts have supplements^[14] such as bisphosphonate^[15], which is used to prevent bone breakdown in osteoporosis. These supplements should keep their muscles and bones in good condition over long periods of time spent without the effects of Earth’s gravity^[16].

Microgravity also affects the nervous and circulatory systems. On Earth, your heart pumps blood upward, and specialized valves in your circulatory system keep bodily fluids from pooling at your feet. In the absence of gravity, fluids shift^[17] toward the head.

My work and that of others has shown that this results in an expansion of fluid-filled spaces in the middle of the brain. Having extra fluid in the skull and no gravity to “hold the brain down” causes the brain to sit higher in the skull^[18], compressing the top of the brain against the inside of the skull.

These fluid shifts may contribute to spaceflight associated neuro-ocular syndrome^[20], a condition experienced by many astronauts that affects the structure and function of the eyes^[21]. The back of the eye can become flattened, and the nerves that carry visual information from the eye to the brain swell and bend. Astronauts can still see, though visual function may worsen for some. Though it hasn’t been well studied yet, case studies suggest^[22] this condition may persist even a few years after returning to Earth.

Scientists may be able to shift the fluids back toward the lower body using specialized “pants^[23]” that pull fluids back down toward the lower body like a vacuum. These pants could be used to redistribute the body’s fluids in a way that is more similar to what occurs on Earth.

Mental health and isolation

While space travel can damage the body, the isolating nature of space travel can also have profound effects on the mind^[24].

Imagine having to live and work with the same small group of people, without being able to see your family or friends for months on end. To learn to manage extreme environments and maintain communication and leadership dynamics, astronauts first undergo team training on Earth.

They spend weeks in either NASA’s Extreme Environment Mission Operations^[25] at the Aquarius Research Station^[26], found underwater^[27] off the Florida Keys, or mapping and exploring caves with the European Space Agency’s CAVES program^[28]. These programs help astronauts build camaraderie with their teammates and learn how to manage stress and loneliness in a hostile, faraway environment.

Researchers are studying how to best monitor and support behavioral mental health^[29] under these extreme and isolating conditions.

While space travel comes with stressors and the potential for loneliness, astronauts describe experiencing an overview effect^[30]: a sense of awe and connectedness with all humankind. This often happens when viewing Earth from the International Space Station.

Learning how to support human health and physiology in space also has numerous benefits for life on Earth^[32]. For example, products that shield astronauts from space radiation and counter its harmful effects on our body can also treat cancer patients receiving radiation treatments.

Understanding how to protect our bones and muscles in microgravity could improve how doctors treat the frailty that often accompanies aging. And space exploration has led to many technological achievements advancing water purification^[33] and satellite systems^[34].

Researchers like me who study ways to preserve astronaut health expect our work will benefit people both in space and here at home.

Online shopping isn’t just a convenient way to buy batteries, diapers, computers and other stuff without going to a brick-and-mortar store.

Many Americans also use the internet to quietly acquire illegal, fake and stolen items^[1]. Guns^[2], prescription drugs no doctor has ordered and checks^[3] are on this long list, as well as cloned credit cards^[4], counterfeit passports and phony driver’s licenses^[5].

Because buyers and sellers alike realize that the authorities can detect illegal online transactions, criminals and their customers prefer covert online platforms that protect user anonymity, such as Tor^[6], or encrypted messaging applications like Telegram and WhatsApp^[7]. Buyers and sellers also use digital wallets^[8] and cryptocurrencies to further conceal^[9] their identities.

As scholars of^[10] high-tech crime^[11], we were eager^[12] to solve a riddle. Having these items shipped to the buyers’ homes or offices would make it easy for authorities to catch them. So how do people who buy these illegal items maintain their anonymity when they take possession of items they purchased on the dark web^[13]?

They mostly use vacant residential properties, called “mule addresses^[14]” or “drop addresses^[15].” Once the illegal goods or phony documents get delivered – presumably without the owners’ knowledge – to the doorstep of the uninhabited home, the buyer or a middleman picks it up. This practice makes it very hard to trace these transactions.

Penchant for sharing

To discover where these items change hands, we took advantage of the inclination of some of the criminal vendors to share images on Telegram of the parcels they send, along with the illicit items.

They use this strategy to build their reputations, earn the trust of buyers and market their services.

Not all users of online underground markets do this, but we still spotted thousands of packages delivered this way over a period of two years.

In one case, we found a photo of a forged or stolen check alongside the mailed envelope used for its delivery on a Telegram channel dedicated to trading stolen and counterfeit checks.

The label on the envelope bears not only the shipping date but also the Wyoming address where it was sent. Armed with this information, anyone can retrieve related details by searching online. We found an apartment complex at that address with several units for rent.

Guns, drugs and rentals

We also found that criminal vendors use mule addresses as their sender address. In one example, we found a video, uploaded in April 2023, of an assault rifle shipped from an Arizona address. At the time, that property was for sale.

The video displays an assault rifle apparently shipped from that address after being purchased online on an underground gun market. At the time, that property was for sale.

We found a similar video documenting the punctual delivery of what we believe to be illegal drugs. Considering that the video has been circulating in illegal drugs markets that we monitor, it’s reasonable to assume that the package contains narcotics or prescription drugs.

The footage portrays a satisfied customer who has just gotten the drugs. We looked up the recipient’s address, which is discernible in the video.

It’s a property in North Las Vegas, Nevada, which was listed for sale at the time of delivery – although it seems to have later been sold. The anticipated delivery date, March 28, 2023, coincided with the day the package in the video was received.

One of the illegal digital marketplaces we identified is a hub for prescription- sales of OxyContin, Viagra, Adderall and Valium. It’s linked to an administrator who presides over several Telegram channels.

The administrator has shared photos on those channels that allowed us to see tracking numbers associated with packages they’d mailed. By collating the tracking numbers from April 20 to May 23, 2023, we compiled a comprehensive database of those addresses and the statuses of those properties when the packages were delivered.

We found that 72% of the 650 deliveries in this database were to properties listed for sale, and the rest were to properties unoccupied for other reasons. The average time that elapsed between a property listing and an illicit package being delivered there was nine days.

Be on guard

We haven’t yet learned of any criminals who were convicted of criminally using mule addresses to deliver illegal packages.

Because criminals take advantage of vacant residential properties listed for sale or rent by unsuspecting homeowners to protect their anonymity, we believe that it’s important for landlords and people who are selling or renting homes to protect themselves from these crimes of commerce.

Some of the same strategies that enhance safety in other regards can help, such as installing surveillance cameras and employing property managers.

Disasters can happen anywhere.

Some places are more prone to hazards such as earthquakes, flooding and hurricanes, but there’s nowhere where the risk is zero. The good news is that humans can make good decisions to lower the odds of such hazards turning into disasters. Technology can help determine where to make investments to save the most lives.

The terrible devastation caused by a 6.8 magnitude earthquake^[1] in Morocco on Sept. 8, 2023, is the result of the presence of centuries-old historic buildings and the continued use of old construction methods^[2] such as clay bricks and unreinforced masonry. These building materials are prevalent worldwide^[3], particularly in developing countries^[4].

Engineers like me^[5] tend to focus on tangible decisions related to how buildings are constructed – for example, the amount and location of steel reinforcement. Over the last several decades, I’ve conducted the world’s largest shake table tests^[6], placing a full-size apartment building on a platform that simulates seismic activity, and I’ve led teams of experts to investigate earthquakes, hurricanes, tornadoes and floods – but I’ve never become used to devastation like we are seeing in Morocco now.

As we are reminded by each disaster, mitigation is needed to make our homes, offices and schools safer and more resilient to earthquakes. Retrofitting buildings is expensive – and that cost represents a daunting challenge for developing nations like Morocco and Syria^[7], as well as developed nations like Turkey – all three of which were devastated recently by major earthquakes.

And yet, I am optimistic because I know thousands of engineers around the world are working and collaborating to make earthquakes less deadly.

How earthquakes devastate buildings

Before we can discuss how to make people safer in earthquakes, it helps to understand the forces at work during these destructive events.

The extent of the damage done by an earthquake is determined by several factors, including magnitude – or how much energy the earthquake releases from the fault – depth of the fault^[9] and how far the building is from the epicenter of the quake.

An epicenter is the location on the surface of the Earth above the fault. Essentially, it is ground zero for the quake, where shaking is most intense and buildings are more likely to collapse.

If the columns and walls of a multi-story building are not stiff and strong enough to resist the forces of an earthquake, gravity takes over. The building usually collapses at the bottom floor level, causing the stories above to follow. Anyone inside can be trapped or crushed by falling debris. Stopping this requires modern design codes^[10], significant investment and enforcement of those design codes. There are always challenges – but that doesn’t mean there haven’t been some success stories.

California plans ahead

Consider the city of San Francisco. More than a decade ago, this densely populated Northern California city realized it had thousands of apartment buildings with parking at the ground level. These are known as “soft-story” buildings and are more prone to collapse because they lack the strength and stiffness of reinforcing^[11] at the ground level. Many are likely to collapse in a moderate-to-major earthquake, while many more would require months to repair.

Through a self-study completed in 2010^[12], San Francisco recognized that even if nobody was killed or injured in an earthquake, damage to these multi-unit residential buildings would result in a significant number of people losing their homes and leaving the city, changing the its character forever. In 2013, the city began a mandatory retrofit program^[13]. So far, more than 700 soft-story buildings^[14] have been retrofitted. Federal grants of up to US$13,000^[15] that became available in early 2023 are expected to accelerate this progress.

Los Angeles^[16] followed suit in 2015, passing a law that required retrofitting of both soft-story wood-framed and older concrete buildings prone to collapse. As of 2023, 69% of soft-story buildings in LA^[17] had been retrofitted. Progress on the concrete structures was slower but is moving ahead.

Retrofitting the larger multi-unit apartment buildings in San Francisco and LA costs between $60,000 and $130,000 – but the investment for a typical single-family home in the U.S. starts as low as $3,000^[18].

Communities outside the U.S. have also built back better after earthquakes.

In 2005, Kobe, Japan, was rocked by a major earthquake that resulted in more than 5,000 fatalities and $200 billion in damage. As the city rebuilt, officials took the opportunity to improve their building code using updated strengthening and stiffening techniques^[19].

Christchurch, New Zealand, was devastated in 2011 by two earthquakes that destroyed much of the downtown area. While many buildings didn’t collapse – a sign that the building code worked to some degree – many were damaged beyond repair. Demolishing them presented an opportunity to focus on resilient construction^[20].

Focusing efforts

So how can people and governments figure out where best to invest to decrease our exposure to natural hazards?

The center I co-direct brings together specialists from 14 universities^[22] to determine how to measure a community’s resilience to natural hazards to enable them to plan for, absorb, and recover rapidly from hazards. A policy directive^[23] during the Obama administration resulted in funds being focused on improving resilience throughout the U.S.

To improve resilience, we have to be able to quantify and measure it. To do this, we’ve developed a computer model called IN-CORE^[24] that communities can use to measure the short- and long-term effects of “what if” scenarios on their households, social institutions, physical infrastructure and local economy. Each interacting algorithm that makes up the model is based on scientifically rigorous research documented in the teams’ almost 200 peer-reviewed publications over the last eight years^[25]. Our system allows stakeholders to make resilience-informed decisions and measure the impacts on vulnerable populations. For example, we know that it is vital that social institutions such as schools and hospitals remain intact^[26] after a hazard event.

One example of utilizing IN-CORE is the center’s engagement with Salt Lake County, Utah. The county is planning for a major earthquake – an event that is inevitable according to experts from the U.S. Geological Survey^[27]. Understanding where investment will have its biggest impact is critical because time and money are limited. Our system will help Salt Lake County determine which building retrofits will provide the most return on investment based on physical services, social services and economic and population stability.

One goal of the IN-CORE Project^[28] is to assist communities recently identified by the Federal Emergency Management Agency as Community Disaster Resilience Zones^[29], or areas in the U.S. most at risk from the effects of natural hazards and climate change.

More broadly, we plan to partner with communities and regions worldwide, always keeping our eye on ensuring socially equitable solutions. For example, as the earthquake in Morocco shows, it is important to consider not just urban centers, but rural communities – like those in the Atlas Mountains that have suffered so much loss^[30].

Curious Kids^[1] is a series for children of all ages. If you have a question you’d like an expert to answer, send it to This email address is being protected from spambots. You need JavaScript enabled to view it.^[2].

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What happens if you have to go to the bathroom in your sleep? – Calleigh H., age 11, Oklahoma

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As you drink water during the day, your body turns extra liquid it doesn’t need into pee. Your bladder stores the urine and eventually alerts you when it’s time to take a trip to the toilet.

But what about at night? How does your body know not to pee while you’re asleep?

Just because you’re snoozing doesn’t mean your body is totally offline – continuous processes like breathing, digestion and, yes, making pee, still happen while you’re asleep. Your bladder and your brain work together to know what to do with that big glass of water you drank before bed.

Using the bathroom every day is routine for many people, so it’s something you might not pay much attention to. But as a pediatric urologist^[3], understanding how the brain and bladder work together – and sometimes miscommunicate – is an important part of my job.

The bladder and the brain

The bladder has two main jobs: to safely store urine and to empty it out. While it seems simple, these two tasks take a lot of complex coordination^[4] of muscles and nerves – that’s the brain’s job.

For babies and young kids, the bladder has reflexes, meaning it automatically knows when to squeeze the muscles to empty the urine. Since babies can’t control this consciously, they typically wear diapers. But as kids grow^[5], the bladder muscles and nerves also grow, which gives a youngster more control over their bladder.

During toilet training^[6], which usually happens by the age of 3 or 4 in the U.S., kids learn how to use the toilet voluntarily. This means that they can feel when the bladder is getting full and their brain can receive and understand that signal. The brain can then tell the bladder to “hold it” until they’ve made it to the toilet and it’s safe to pee.

What happens in sleep mode?

Most children first learn how to use the toilet during the day. Using the bathroom overnight can be more difficult^[7] because the sleeping brain doesn’t receive signals in the same way as when awake.

While awake, if there’s a loud noise or a bright light, the body senses it and reacts. But during sleep, the body may not hear that noise or see that light because the brain is in sleep mode^[8]. Imagine sleeping through an overnight thunderstorm that you didn’t realize happened until you hear people talking about it in the morning. Your brain didn’t process the loud noises because it was focusing on sleep.

The same thing can happen with bladder signals. The bladder fills with urine 24 hours a day, even while you’re snoozing, and it sends signals to the brain when it’s full. In order to help you get enough sleep, your brain will tell your bladder to hold it until morning.

Sometimes, if you really need to go, your brain will tell your body to wake up so you can go empty your full bladder. While it’s normal to wake up to pee sometimes – especially if you drank a big cup of hot chocolate right before bed – most older kids can usually sleep through the night without needing to use the toilet.

When the brain and bladder are working together well, your bladder gradually fills up overnight and hangs on til morning when you stumble into the bathroom to empty it.

Nighttime accidents

But there are many ways the communication between the brain and the bladder can break down. For one, the brain may not get the bladder’s message that it’s time to go. Even if the brain gets the message, it may not be able to tell the bladder to hold on. Or, when the bladder can’t wait, the brain might not tell your body to wake up. If the signals and messages aren’t sent, or are received incorrectly, the bladder will go into reflex mode^[9] – it squeezes to empty itself of pee, even though you’re fast asleep in bed.

Wetting the bed at night, which doctors call nocturnal enuresis^[10], is more common than you might think. About 15%^[11] of kids between ages 5 and 7 wet the bed sometimes. Even some teenagers experience it. It’s more common in boys, and often there’s a family history, meaning parents or relatives may have dealt with nighttime accidents too.

There are a few reasons why nighttime wetting happens. Since kids’ brains are growing and developing, nighttime communication between the brain and bladder can take longer.

Some bodies make more pee at night, making it more likely the bladder will get full during sleep. Some people have smaller bladders that fill up fast. Sometimes having difficulties with sleep or being a deep sleeper can make it harder^[13] to wake up at night if you really need to pee.

Most kids who wet the bed at night outgrow it as their brains and bodies continue to develop. At that point, they can sleep through the night without needing to pee, or their bodies are able to wake up at night to use the bathroom when they need to.

If wetting the bed is an issue, there are some things that can help^[14], like drinking less liquid in the evening or using the bathroom right before you go to bed. These precautions make it less likely that the bladder will be too full during sleep. There are also bedwetting alarms that can help train the body to wake up when the bladder needs to be emptied. If there are concerns about nighttime accidents, or if accidents start happening in older children, I recommend consulting a doctor.

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Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to This email address is being protected from spambots. You need JavaScript enabled to view it.^[15]. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.