Why do people get carsick?

You may have experienced this yourself during a drive through the mountains with sharp cornering; you start feeling unwell dizzy, and tired. After a while, you may even feel nauseated and, during a worst-case scenario, feel the need to vomit. Yet, as a driver, you usually don't feel sick at all during similar drives. Why is that?

Being carsick can be a great nuisance - Image Credit: Nicoleta Ionescu via Shutterstock - HDR tune by Universal-Sci

Being carsick can be a great nuisance - Image Credit: Nicoleta Ionescu via Shutterstock - HDR tune by Universal-Sci

Carsickness is a form of motion sickness. If you suffer from carsickness, you may also suffer from other forms of motion sickness like seasickness or VR motion sickness. Motion sickness has been studied extensively for years as it can be quite a problem in sectors like the shipping industry and the aviation industry. It is a more complex matter than you would initially think, and there are still a few open questions.

What causes carsickness?

To understand motion sickness, we need to take another look at the vestibular system, just like we did in our article: Why do you get dizzy when you're drunk? 

Motion sickness is triggered when signals arriving in the brain from your eyes, the inner ear (which forms the base of the vestibular system), and the otolith (which identifies mechanical motion/acceleration and converts it to electrical signals) contradict one another

A schematic overview of the vestibular system. Each inner-ear has one of these. - Image Credit: Designua via Shutterstock / Edited by Universal-Sci - (click to enlarge)

For a real-world example of when these conflicting signals may occur, you can think of a situation where you are looking at a motionless object like a book while sitting in the back seat of a car. 

Your eyes will notify your brain that the book you are looking at is motionless from your perspective. Meanwhile, the signals arriving in your brain that stem from your vestibular system convey conflicting information when the car accelerates or takes a turn as the g-forces generated by these actions indicate motion. 

Why don't you get carsick when you drive yourself?

One might ask why most people who get carsick don't become nauseated when they drive themselves. 

This phenomenon can be attributed to the fact that when someone has control over the wheel, they are in control of the direction the car is moving. There is no puzzle in your brain stemming from confliction signals; the person driving knows what is happening and what is going to happen.

Image Credit: mimagephotography via Shutterstock - HDR tune by Universal-Sci

Image Credit: mimagephotography via Shutterstock - HDR tune by Universal-Sci

How can you prevent carsickness?

According to Dr. Herman Kingma, vestibulologist at Maastricht University, one of the simplest things you can do to prevent carsickness or motion sickness in general is to trick your brain a bit and focus on something other than the fact that you are moving.

You won't be able to do that by reading a book because it remains evident that you are moving while reading. Kingma recommends doing something that demands your attention in a more immediate fashion, like playing a video game. 

A video game tends to emerge you quite quickly as it typically requires your constant input, making you quickly forget the fact that you are sitting in a moving car.

According to Kingma, there has been a steady decline in carsickness in children since the general emergence of handheld games.

Why is seasickness worse than carsickness?

A phenomenon that may even be worse than carsickness is seasickness. Being on a boat exposes you to a unique combination of translational motion and tilts. 

These types of movements are particularly challenging for your vestibular system to process. On a boat, you will typically lose your orientation to gravity very quickly. Research shows that the vestibular system has the most difficulties with repeating motions at a frequency of about 5 seconds.

At the moment you lose your orientation, a kind of warning signal will reach your brain, cautioning you that things are escalating. You will feel nausea coming on slowly, especially if you have a well-developed connection between your vestibular system and the vomiting center in your brain. 

Image Credit: Maridav via Shutterstock - HDR tune by Universal-Sci

Image Credit: Maridav via Shutterstock - HDR tune by Universal-Sci

How to deal with seasickness?

If you are exposed often enough to the typical motions of a boat at sea, you can actually get used to it. Your brain will eventually save these typical motion patterns creating a new reference frame. Sadly, 10% of people will never get used to it even after extensive exposure. 

Kingma stated that sleep medication can help you sustain a boat trip as it lowers your brain's concern with orientation. However, this is, of course, not an ideal solution.

So what can you do? First, it is a sound strategy to have a proper rest before departing on a boat trip. When you are tired, you are more prone to motion sickness. 

When you are on board and start to feel queasy, it may also be beneficial to get some fresh air and keep your eyes on the horizon, helping you to keep your bearings. Try to relax and focus on your breathing, taking your mind off things. It goes without saying that you should avoid activities like reading. 

Sources and further reading:

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