• Published on: Jul 24, 2023
  • 2 minute read

Stomachs Growl, Noses Run, And Yawning Is Contagious: The Science Behind These Peculiar Human Reactions

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Have you ever found yourself in an awkward situation when your stomach growls loudly in a quiet room, or your nose starts running uncontrollably on a chilly day? And what about that moment when you see someone else yawn, and suddenly, you find yourself yawning too, even though you're not sleepy? These peculiar human reactions have fascinated scientists and puzzled us for years. In this blog post, we'll explore the fascinating science behind why stomachs growl, noses run, and yawning becomes contagious.

1. Why Do Stomachs Growl?

Stomach growling, also known as "borborygmi," is a common phenomenon that often occurs when we're hungry. But why does our stomach make such a loud noise when it's empty? The answer lies in the process of digestion. When our stomach and small intestines are empty, they contract and move air and fluids, which can produce the rumbling or gurgling sounds we hear.

During digestion, the stomach and intestines break down food and extract nutrients to provide energy for our body. When the stomach is empty, these contractions continue as a way to sweep away any remaining food particles and prepare for the next meal. As a result, we hear those familiar grumbling sounds. It's worth noting that stomach growling can also occur after we've eaten, but it's usually less noticeable due to the presence of food in the digestive tract.

2. The Runny Nose Dilemma

A runny nose can be annoying, especially when you least expect it. But this bodily reaction is actually an important defense mechanism. When we encounter irritants like dust, pollen, or viruses, our body activates its immune response to protect the respiratory system.

The lining of our nasal passages contains specialized cells that produce mucus, acting as a sticky trap for foreign particles. When irritants are detected, the body increases mucus production to catch and remove them from the nasal passages. This excess mucus, along with the fluid from swollen blood vessels, leads to the all-too-familiar runny nose.

While it may be bothersome, a runny nose is a sign that your body is actively defending itself against potential threats and keeping your respiratory system healthy.

3. The Contagious Yawn

Yawning is one of the most contagious and intriguing human behaviors. Just witnessing someone yawn can trigger the same response in others, even if they are not tired. Scientists have found that contagious yawning is linked to social and emotional factors.

Yawning is associated with empathy and social bonding. When we see someone yawn, our brain recognizes the action as a sign of fatigue or drowsiness. In response, our brain releases chemicals like oxytocin, also known as the "love hormone," which enhances our ability to connect with others. This neurological reaction is why we often find ourselves yawning in response to someone else's yawn, as our brains interpret it as a signal to empathize and strengthen social bonds.


Stomach growling, nose running, and yawning becoming contagious are all fascinating physiological phenomena with underlying scientific explanations. Our bodies are intricate and sophisticated, and these reactions serve essential purposes in maintaining our overall health and well-being.

Next time you hear your stomach growl or find yourself yawning in response to someone else, remember that it's all part of the incredible complexity of being human. Embrace these quirks and appreciate the wonders of our bodies and the intricate ways they respond to the world around us.

Read FAQs

A. Stomach growling, also known as borborygmi, is caused by the movement of gas and fluids in your gastrointestinal tract. When your stomach and intestines contract and move food and air, it can create these rumbling noises. This is a normal bodily function and usually occurs when your stomach is empty, signaling that you may be hungry.

A. A runny nose is often a sign of the body's immune response to irritants, viruses, or allergens. When your nasal passages are exposed to these substances, the body releases histamines, which cause the blood vessels in the nose to dilate, leading to increased mucus production. The excess mucus flows out of the nose, causing it to "run."

A. Yawning is considered contagious because of social and psychological factors. When we see someone else yawn, it triggers a phenomenon known as "social yawning." The human brain is wired to imitate the behavior of others, and yawning is no exception. It is believed that contagious yawning may be linked to empathy and social bonding, as it often occurs in response to seeing someone else's fatigue or boredom.

A. While stomach growling can be associated with hunger, it's not always the case. The digestive system continues to contract and move even when you are not hungry, so you might experience stomach growling even after a meal. Other factors, such as consuming certain foods, anxiety, or stress, can also contribute to stomach growling.

A. In many cases, a runny nose is a common symptom of allergies or viral infections like the common cold. However, persistent or chronic runny nose, especially accompanied by other symptoms like facial pain, headaches, or loss of smell, could indicate other health issues such as sinusitis or nasal polyps. If you have concerns about your runny nose, it's best to consult a healthcare professional for a proper diagnosis and treatment.

A. Yawning serves several physiological functions. One of the primary purposes of yawning is to regulate brain temperature and increase oxygen intake. Yawning is believed to cool down the brain, enhancing alertness and mental clarity. Additionally, yawning may help stretch and relax facial muscles, providing a quick moment of relief and relaxation.

A. Contagious yawning is an involuntary response triggered by seeing someone else yawn. While it is difficult to consciously prevent contagious yawning, some studies suggest that focusing on the person's eyes instead of their mouth may reduce the likelihood of "catching" a yawn. However, more research is needed to fully understand the mechanisms behind contagious yawning and how to control it.

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