I have vivid memories as a kid, sitting in the backseat of our station wagon in the rear-facing seat (why was there a seat that faced backwards? How was that a good idea?) of our many family road trips, opening up a good book ... and then promptly throwing up. And I know I’m not alone. I actually have a friend who keeps a plastic bag next to her son’s seat for every car trip, just in case he gets sick. So what gives? What happens to us when we experience car sickness?

Car sickness falls under the general umbrella of motion sickness (of which sea sickness and the less common air sickness are other subcategories). The reason we get nauseated and feel like we need to throw up when we’re not moving in a moving car relates to our ability to process motion and our sense of equilibrium.

We have two ways to process signals that affect our equilibrium – through our eyes and through our ears. When we are sitting in a moving car, and looking at a book, for instance, or looking at one point in the car, our eyes are sending the message to the brain that we are not moving, because the book and the inside of the car are both stagnant items that don’t move. The problem lies in that our inner ear, the part of the ear responsible for maintaining our sense of equilibrium, is sending a different message to the brain because it experiences movement each time the car jerks or the driver steps on the brake, presses on the gas, or goes over a bump in the road. That part of our body is sure that we are, in fact, in motion.

These mixed signals wreak havoc on our brain. Are we moving or are we not moving? Our brain isn’t sure, and as a result, it inevitably sends the signal to our stomach to send back our lunch from whence it came.

To resolve the imbalance, there are two things you can try: Either align the mixed signals by looking out the window — since your eyes will see that you are actually moving, you won’t have the same conflicting signals and your brain will get it together. (Incidentally, this is why the driver doesn’t get car sick, because his eyes are always focused outside the car…or so we hope.) You can also try tuning out one of the signals by closing your eyes. It can also help to open the window and get some fresh air. Of course, if you know this kind of thing happens to you, you can ward off a possible queasy feeling (and icky mess) by not reading in the car, and making sure to look out the window (that’s cracked open, of course). Or, if you’re prone to these kinds of things, you can always volunteer to drive.

As the old proverb goes, “Better to drive and not be sick, than not to drive and be sick.” Or something like that.

Related on MNN: