popular science

motion sickness

You found yourself on a back of a car or a bus, traveling but sitting steadily, reading a comic book or scrolling trough endless wonders of Instagram.

All of a sudden, you feel nauseous.

Oh-oh! I’m afraid you’re caught by motion sickness, darling.

It’s kinda self-explanatory, but this kind of strange occuring nausea usually happens when you’re in mechanical motion, aka traveling by a car, boat, and in some cases even a train or a plane.


Basically, your body’s sensory organs send mixed messages to your brain, causing dizziness, lightheadedness, arghhhh vomiting! Remember those black bags they hand down to you during high school bus trips?


Some people (lucky bastards like me) learn early in their lives that they’re prone to this condition. Sigh.

But, the story is that motion sickness, kinetosis, simulation sickness, space motion sickness, space adaptation syndrome, Sopite syndrome (even seasickness — nausea in Greek, from naus meaning ship) slowly vanishes with your age. If that’s some kind of consolation.

At the moment, a “fully adequate theory of motion sickness is not available”. Hm.

But, contemporary sensory conflict hypothesis, referring to [big sciency words] “a discontinuity between either visual, proprioceptive, and somatosensory input, or semicircular canal and otolith input”, is probably the most thoroughly studied.

Let’s dig into it.

According to this hypothesis, motion sickness happens when the vestibular system (the sensory system that provides the sense of balance, spatial orientation and movement coordination in most mammals) and the visual system don’t present a synchronized and unified representation of your body and/or your surroundings.

In other words — You are motion sick the moment you visually perceive that your surroundings are relatively immobile, while the vestibular system reports to the brain that your body is in motion relative to its surroundings.

Space motion sickness, on the other hand, can occur when the visual system perceives that one’s surroundings are in motion while the vestibular system reports relative bodily immobility (as in zero gravity).

The defense mechanism hypothesis is holding that motion sickness functions as a defense mechanism against neurotoxins.

The area postrema in the brain is responsible for inducing vomiting when poisons are detected, and for resolving conflicts between vision and balance. When feeling motion but not seeing it (for example, in the cabin of a ship with no portholes), the inner ear transmits to the brain that it senses motion, but the eyes tell the brain that everything is still. As a result of the non-syncs, the brain concludes that the individual is rather hallucinating. And what does the brain do? It concludes that the hallucination is due to poison ingestion.

You vomit to get the supposed toxin out of your system.

Roughly one-third of the population is highly susceptible to motion sickness, and most of the rest may get motion sickness under extreme conditions. The incidence of space motion sickness has been estimated over the years at between forty and eighty percent of those who have entered weightless orbit. Children between the ages of 2 and 12 are most likely to suffer from motion sickness. Pregnant women also have a higher likelihood of experiencing this kind of inner ear disturbance. Statistics indicate that women are more likely to be affected than men, and that the risk decreases with advancing age. There is some evidence that people with Asian ancestry may suffer motion sickness more frequently compared with people of European ancestry, and there are situational and behavioral factors, such as whether a passenger has a view of the road ahead, and diet and eating behaviors.

Once again, huge kudos to astronauts, pilots and the rest of the terrestrial, aero and nautical superhumans.

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