The body is actually doing something behind the brain's back!

During the holidays, you are busy visiting relatives and friends, eating, drinking and having fun. Have you noticed that in daily life, our bodies produce some small movements that are beyond our control? The most common ones are eyelid twitching, leg shaking, sudden muscle twitching, etc. It's strange, shouldn't people be able to control their own behavior? Then how to explain these sudden shivers?

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#1 Eyelid twitching

As the saying goes, if your left eye twitches, you will get rich, but if your right eye twitches, you will get bad luck. Ancient people liked to use metaphysics to rationalize natural phenomena that they could not explain. The eyelids are responsible for closing the eyes, and this action is completed by the orbicularis oculi muscle surrounding the eyes. Muscle movements are controlled by nerves, and eyelid twitching is medically called "eyelid tremor", which is the abnormal excitement of the nerves that control the eyelid muscles. The nerves are excited for no reason, and some of the orbicularis oculi muscle fibers cannot continue to contract autonomously in a short period of time, which affects the skin covering these muscles, thus causing eyelid twitching.

It is not entirely accurate to say that there is no reason. Under normal circumstances, when the eyes are stimulated, the eyelids close, which is a natural behavior to protect the eyes. For example, strong light, stimulation caused by drugs, foreign objects blown into the eyes, frequent smoking and drinking, etc., may irritate the eyes and cause this movement. When people are overly tired, use their eyes for too long, or lack of sleep, although they are not subjectively aware of these stimuli, eye fatigue may frequently cause eyelid twitching.

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In addition, some diseases may also cause pathological eyelid twitching. For example, elderly people with cardiovascular and cerebrovascular diseases have hardened and twisted blood vessels in the brain stem, and the facial nerve that controls the eyelid muscle movement is compressed by the blood vessels, resulting in persistent abnormal nerve excitement, causing the muscles to contract continuously and the eyes to blink continuously. This is eyelid spasm, which is difficult to heal on its own. Generally speaking, pathological eyelid twitching lasts for a long time and the blink amplitude is large, so it is easy to distinguish.

#2Shake your legs

There is a medical term called "restless legs syndrome", the main symptom of which is uncontrollable shaking of the legs, which is similar to our daily shaking behavior. However, this restless legs is a neurological disease, which is related to abnormal dopamine metabolism and iron deficiency, and has certain genetic factors.

Patients with restless legs syndrome cannot control their shaking legs, and they experience intense pain, burning sensations, and leg cramps. Late at night, patients often cannot fall asleep due to the hyperactivity of their muscles. However, the shaking legs in our daily lives are not so terrible, as they are all controllable and most of them are not diseases, but just a habitual action.

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Daily leg shaking is not a disease, nor does it help your health. Although some people say that leg shaking can relieve the problem of poor blood circulation in the lower limbs caused by long-term sitting, if it is caused by long-term sitting, the best solution is to get up and walk around. Some people also say that leg shaking can relieve tension and anxiety, which is just like some habitual actions in people's lives, such as spinning pens and snapping fingers, which is just a psychological dependence. What's more, leg shaking is considered an indecent behavior, so it's best not to develop this habit.

#3 Sleep Twitching

This type of muscle twitching is medically called "muscle twitching". It is a rapid involuntary muscle twitching, similar to the action of electric shock. Physiological muscle twitching also includes hiccups, muscle twitching caused by fatigue or tension. These movements also occur in normal people's daily lives and have little to do with physical health.

So, what exactly causes this phenomenon of suddenly kicking one's legs while falling asleep?

This can be divided into two situations. When you are about to fall asleep and are half asleep, you may suddenly twitch, sometimes accompanied by a feeling of free fall or even a vague dream, and you may wake up because of it. This is called "hypnic twitching". This twitching generally does not affect sleep. There are many different opinions about its cause. Some people think that when people fall asleep, their heart rate slows down, their body temperature drops, their breathing slows down, and their muscles relax accordingly. The system responsible for this conversion process occasionally makes some small mistakes.

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Another interesting explanation is that the human brain evolved from the reptile brain, so it still retains some of the reptile stress response patterns. When the muscles are completely relaxed, the brain thinks we are falling freely. In order to protect ourselves, the brain commands the muscles of the whole body to act immediately, trying to catch something during the fall. As a result, the already relaxed muscles will suddenly tighten, causing sleep twitching.

The twitching that occurs after you fall into a deeper sleep is called "muscle twitching". It is caused by a special brain wave "sleep spindle" in the thalamus and cerebral cortex. Specifically, the brain wave suddenly oscillates violently, which may be accompanied by sudden twitching of local muscles in the body.

Since this type of muscle twitching during sleep is common in infants, some researchers believe that this process is the brain learning or consolidating the correspondence between nerves and muscles, and this learning is easier to complete during sleep without external stimulation. This can also explain why infants seem to sleep all day long. It turns out that they are diligently carrying out "twitch sleep learning".

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Moreover, this occasional brain wave oscillation can help us sleep well and protect our sleep when there is a sudden external sound stimulation. A study by the Department of Sleep Medicine at Harvard Medical School showed that the more frequent the occurrence of sleep spindles in brain waves, the stronger the individual's ability to resist external interference and maintain sleep, and the better the sleep quality.

#4 What you don’t know…

The human body is not as easy to control as you think. For example, your cardiac muscle and smooth muscle are moving silently without your noticing.

Myocardium begins to contract and relax without complaint from the third week of embryonic development, making the heart beat. Even an isolated heart will still show autonomous contraction and relaxation activities for a short period of time.

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The smooth muscles that are widely distributed in the esophagus, stomach, intestines, bronchi, urethra, bladder, the inner wall of blood vessels, and even in the skin are under the dual control of the autonomic nervous system and the endocrine system, and can remain tight for a long time. Even if we temporarily neglect it subjectively, the smooth muscles will continue to work consciously to make the organs move or maintain their original shape.

Therefore, your body is already performing some small movements that you are not aware of, so it is not surprising that some sudden physical reactions occur for no reason.

Source: Chongqing Science and Technology Museum

Author: Tao Zhi, PhD student in ecology

Review experts: Huang He, Li Chunli, Chen Tao, Xu Xiaoping

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