Why do some people get carsick? Maybe they are poisoned

Motion sickness, scientifically known as motion sickness, is essentially motion sickness, just like seasickness and airsickness. As early as more than 2,000 years ago, the ancient Greek doctor Hippocrates discovered that sailing on the sea would affect the human body, causing dizziness and vomiting.

Although motion sickness has been discovered for a long time, the physiological causes of motion sickness are still unclear.

"Sensory conflict" is the most commonly hypothesized cause of motion sickness.

Specifically, humans perceive their position and state mainly through two systems: one is vision, which is the direct vision of the eyes, and the other is the vestibule in the inner ear, which can sense the state of movement and position changes of the human body. If you close your eyes and plug your ears, you can still know whether you are walking, standing, or sitting down, thanks to the vestibule. Under normal circumstances, the two work together, and you can successfully complete various movements.

However, when the signals they receive are inconsistent, people will experience symptoms such as dizziness (a sound), nausea, and vomiting.

The picture comes from Tuchong.com

Take motion sickness as an example. When the car moves forward, the vestibular system will keenly sense that you are moving forward, but the eyes will see that the surrounding environment has not changed, and will tell the brain that you are not moving. The brain is confused, and motion sickness occurs. Following this idea, when riding in a car, pull over, look out the window, and don't lower your head to read a book or play with your phone, etc., which can alleviate motion sickness, because they are actually letting your eyes know that you are moving rather than standing still, avoiding conflicts with the vestibular system.

In addition to "sensory conflict", some people believe that motion sickness may be caused by people's own defense mechanism. A 1977 study showed that after a person is poisoned, the vestibular system may be affected, and vomiting is one of the fastest ways to expel toxins. Therefore, during the long process of evolution, humans gradually formed this set of defense mechanisms, that is, vomiting occurs when the vestibular system encounters problems.

Coincidentally, as mentioned before, when you are carsick, the vestibular system and the visual system have different cognitions, so the brain will mistakenly think that you are poisoned, and then vomit quickly...

Two papers published in 2014 and 2016 further explored the "poisoning hypothesis" based on this. According to these two papers, when people get carsick, they will sweat and their body temperature will drop, which happens to be a common symptom of poisoning. Therefore, researchers believe that a series of symptoms of motion sickness may be caused by the wrong activation of the body's own defense mechanism.

Although motion sickness is just a minor problem, as people study it in depth, they will gradually uncover the secrets of their own bodies.

This article is a work supported by Science Popularization China Starry Sky Project

Author: The Nutcracker

Review: Tao Ning

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

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