Motion sickness: what are the causes?

Do you ever feel sick during a car trip after looking at your smartphone or a book for a few minutes, while the person next to you seems to be able to do it without difficulty? What causes motion sickness?

Motion sickness, also known as "kinetosis", can quickly turn even the smallest trip into an unpleasant experience, and affects between 25 and 30% of people. The most common symptoms are nausea, dizziness, headaches, and vomiting. Depending on the person, these signs appear during trips with all or only certain means of transportation, and they usually stop shortly after exiting the vehicle.

But what are the causes? The best known hypothesis is that of sensory conflict. Indeed, during a trip, the information transmitted by the inner ear and by the eyes are discordant because the body does not move while the visual system perceives a movement. Of course, some factors favor motion sickness, such as inner ear disorders (Meniere's disease for example), fatigue, alcohol and tobacco abuse, and being a passenger. Children between the ages of 2 and 12 and women also seem to be more frequently affected.

This phenomenon is not limited to real journeys, as the term "cyberkinetosis" has appeared since the appearance of virtual reality helmets. Indeed, the gap between the sight and the sensory system is increased in this situation. But again, some individuals are affected while others are not, and the reason why is still not clear…