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Motion Sickness & Nausea

Frequently Asked Questions (FAQs)

 

Will self-driving cars cause motion sickness for most people?

I didn't see anything in this report the explained how self-driving cars differed from being in a taxi.

They seemed to compare to buses, trains and driving yourself. But the 'small vehicle subject to more lateral motion and acceleration' sounds very much like riding in a taxi.

But sure, some people shifting from driving themselves, regardless of what sort of driver is operating it, will be a major shift for everyone.

 

How do fighter pilots not get motion sickness?

Motion sickness typically occurs when the eyes disagree with the vestibular organ; in other words, when the movement you feel is different from the movement you see. This is much less likely to happen when you keep your eyes outside the vehicle. Pilots spend most of their time looking outside the cockpit, so it's usually not a problem. Also, a cockpit has an expansive, open canopy with few obstructions to view, unlike cars and commercial airliners where you are afforded a much smaller view of the outside world. This also helps prevent motion sickness.

 

Do insects get motion sickness?

I recall reading in "Fly: The Unsung Hero of Twentieth-Century Science," by Martin Brooks (I think that was the book) about a gene that makes adult fruit flies spin in circles...forever. All their motion is in a circle, the fly can only spin. He said the flies eventually die of "advanced motion sickness."

I haven't been able to verify that or remember the name of the gene. Also, a big problem: motion sickness is caused by a mismatch between what you see and your sense of balance, or other cases where two stimuli send conflicting signals. Insects don't have the same sense of balance that we do: they don't have an inner ear. Without that, I don't think motion sickness is possible for an insect, although they certainly can detect their body position and have a sense of balance. It's possible that they get motion sick, or get dizzy, but it would be very hard to test.

 

Is it possible to overcome motion sickness? How?

If it's in the car, it generally helps to keep your eyes on the horizon or the road ahead. This helps the brain correlate the movement of the body with the surroundings, and anticipate its movements.

In my experience, reading in the car or the bus will make you motion sick every time, because the brain cannot correlate the movement of the car, the acceleration, deceleration, and turns, with the non movement of the printed page in front of you.

What's worse, reading in a moving vehicle is actually dangerous to your eyesight. Because the printed text is jerking and moving, the eyes have to move a lot more to keep track of the text, which places additional strain on the orbital muscles. According to anecdotal evidence this can possibly cause myopia.

 

Can a person suffering from motion sickness turn out to be a good/decent driver? If so, then how?

I get carsick when sitting in the back seat, or when facing the opposite way (looking backwards when going forward, looking forward when going in reverse). I have experienced this since I was a child. It's instantaneous nausea, and it takes much longer for the feeling to go away than it did to come on. I also get violently ill on boats.

However, I have never gotten sick as a driver. I've been driving for almost 20 years and I've never experienced motion sickness from the driver's seat. I think it has something to do with my focus forward, eyes always on the road.

 

How do I train myself to overcome motion sickness when I'm reading in a moving vehicle?

I've had car sickness on long trips since childhood. I find nibbling on something plain and dry like pretzels will help. Also don't try to read. Listen to music or an audio book.

 

What is a scientific explanation for motion sickness?

Motion sickness happens when what your vestibular sensory organs detect doesn't match up with the motion that your brain expects to happen. The vertical vector (moving up and down) of car/boat/air travel is believed to be involved the most in producing motion sickness. When the sensory information does not match what the brain expects to happen, some complex neurotransmitter release happens, including dopamine and serotonin, which stimulates the emetic centre in the brain. It's this stimulation of the emetic centre that produces the nausea of motion sickness.

 

Why are some people more prone to motion sickness than others?

While there is no concensus as to why motion sickness arises, there are two hypotheses that have been proposed. These are:

1. 'Toxin Detector' hypothesis - proposes that motion sickness evolved as a backup mechanism by which toxins can be identified. According to this, motion sickness is the natural response to novel and abnormal sensory stimuli resulting from a change in physical environment as experienced through vision and force sensation. As proof, it cites experimental results that suggest that people who are more sensitive and susceptible to toxins also experience motion sickness more.

2. 'Vestibular-Cardiovascular Reflex' hypothesis - proposes that motion sickness arises from a need to retain a stable internal environment in the face of unnatural forces and stimuli, necessitating the activation of certain vestiubular-cardiovascular reflex actions. As supporting evidence, it cites experimental results which indicate that certain neuronal networks begin to function in an abnormal manner prior to experiencing the pangs of motion sickness.

It's believed that every individual possesses three independent qualities that determine their sensitivity and susceptibility to motion sickness, these being:

a) Initial sensitivity to motion

b) Adaptation rate

c) Retention rate of protective adaptation

Research has identified a host of factors that might impact the above three parameters. Some of those deemed to be the most important are:

1. Age - Motion sickness is reportedly absent below the age of 6 years and susceptibility is at a maximum around the age of 9-10 years. Since this is pre-puberty, the observation has been explained by suggesting the inherently plastic nature of the neural sensory-motor map below the age of 7 years. At older ages, susceptibility is proposed to decline as a result of behavioral habituation.

2. Sex - Women appear to be more susceptible than men on the average, an observation that is hypothesized to be due to the menstrual cycle. Another hypothesis posits that this is advantageous on evolutionary grounds to reduce susceptibility of the fetus to toxins.

3. Medical problems - People who suffer from migraines or Ménière's disease are believed to be more susceptible to motion sickness. The molecular mechanisms by which these are inter-related has also seen a lot of study, though that is not very relevant in this context.

4. Genetic makeup - It is thought that genetic predisposition could affect motion sickness risk by altering the neural networks in place for vestibular reflex actions though details are still sketchy.

5. Habituation - Studies have reported the reduction in motion sickness as the time for which it has been experienced increases. However, since there are many types of stimuli which can cause motion sickness and many are believed to be independent of each other, habituation to one stimulus would likely not generalize to any others.

As can be seen, these factors help to explain differences at a very gross 'average' level. We are still far from elucidating susceptibility differences at the level of distinct individuals, and it is felt that a molecular theory for the cause of motion sickness would be the best method to proceed towards this goal.