What changes will happen to people who hug frequently? You will never expect the last one!

Hugging, this simple yet powerful physical action, is a way of expressing love that we often overlook in our daily lives. In order to encourage everyone to hug their family and friends more often, American Kevin Zaborney initiated the National Hugging Day in 1986, which is held on January 21 every year. Why can this simple action of hugging bring such a wonderful experience? Where does its magic come from?

"Pleasant touch" makes us fall in love with hugs

For humans, the tactile system is not only the most widely distributed sensory system, but also the earliest sense that allows humans to feel cared for, loved, and safe. While the sense of touch creates a unique sensory experience for humans, it also makes humans fall in love with hugs.

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In 2022, a study published in the journal Science found that if you touch the back of a mouse with a brush, the mouse's heart rate will drop, its tolerance to pain will increase, and the level of stress hormones in its plasma will also decrease. The researchers speculate that this is because animals have a special sensory system that can be activated by positive social touches such as gentle stroking and hugging, which they define as: pleasant touch. They found that when mice enjoy "fur-stroking", the PROKR2 neurons in their spinal cords are activated. When scientists destroy this neuron, the mice become indifferent, unwilling to stick to their companions, and do not like to be fur-stroking. A year later, another study published in the journal Cell once again proved the existence of "pleasant touch" and found special neurons used to feel this touch-Mrgprb4 neurons. This is a type of neuron distributed on the skin. When the skin feels hugged and caressed, this group of neurons sends signals to the brain, which are transmitted step by step to the brain areas related to reward and pleasant experience, and promote the brain to release "happy hormones"-dopamine. Under this mechanism, the brain interprets a hug as a reward signal that can bring happiness.

When we hug, our bodies...

The simple action of hugging awakens not only the "pleasant touch" but also a series of physiological changes. Some studies on married couples have found that hugging increases the level of oxytocin in their bodies. Oxytocin, also known as the "cuddle hormone", is a hormone that can enhance intimacy and trust and reduce anxiety. Because of this, hugging can make people feel safe, and couples can deepen their feelings by hugging each other frequently. Oxytocin also has an important function - activating the sympathetic nervous system, switching the body's working mode from "movement" to "stillness", from tension to relaxation. Therefore, a large number of studies have reported that hugging can reduce heart rate, blood pressure, and calm mood. A warm hug before going to bed can bring higher quality sleep. Hugging can also make the brain secrete endorphins and serotonin. Endorphins are a hormone secreted by the pituitary gland and are natural analgesics in the body. Therefore, hugging when you feel uncomfortable can have a physiological analgesic effect. Serotonin is the "happiness hormone" in our body. It can constantly send positive emotional signals to the body and can bring us a positive attitude and a feeling of happiness. So, when we are in a bad mood, a big hug can really cheer us up.

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Hugging can also expel negative energy from the body. When you hug tightly, the level of cortisol, a "stress hormone", in your body will decrease, and your ability to resist stress will increase. However, this study showed differences between men and women. The men who participated in the experiment did not show a significant decrease. The researchers said that this may be due to social factors. Hugging is an embarrassing behavior for many men.

Can hugging often improve immunity?

Modern people live a fast-paced life and are often in a high-pressure environment. They are not only prone to negative emotions such as anxiety and depression, but also have a lower resistance. In this regard, the research team of Carnegie Mellon University proposed a very simple method - hug others more often to improve resistance!

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The team surveyed 404 healthy adults, asked them about recent interpersonal conflicts to assess their recent social stress, and recorded the frequency of their hugs to understand their social support, and then exposed them to the influenza virus. The results showed that among the infected volunteers, those who had more social support (more frequent hugs) had milder symptoms. The researchers explained that the social stress caused by interpersonal conflicts can lead to a decrease in the immune system's ability to fight disease. Being hugged by trusted people is a strong social support that helps relieve stress and prevents stress from weakening the immune system. If you are under stress, try this method and get close to the people you love!

References

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Planning and production

This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Hardy, PhD in Neurobiology, Zhejiang University

Reviewer: Li Jingjing Professor and Chief Physician, Department of Neurology, Beijing Tiantan Hospital