How Motion Sickness Works

By: Melanie Radzicki McManus

You can get motion sickness in a car, on an amusement park ride, from watching a 3D movie or even looking through a microscope.
You can get motion sickness in a car, on an amusement park ride, from watching a 3D movie or even looking through a microscope.
Vincent Besnault/Getty Images

You're riding in the car, trying to get a little work done on your laptop, when you're hit by a sudden wave of nausea. You're going to become carsick. If you're lucky, you can simply look up from your laptop for a few minutes and you'll be fine. If not, you'll have to put it away for the rest of the trip. Maybe unroll the window, too, or have the driver pull over so you can get out and gulp some fresh air. You might end up puking no matter what you do. And if you're very unfortunate, your stomach might remain queasy for the rest of the day.

About 25 to 40 percent of people are susceptible to motion sickness, the term used to cover any kind of ill feeling resulting from movement, whether in a car, boat, airplane or amusement park ride [source: Reddy]. You can also develop motion sickness by watching a 3-D or IMAX movie, playing video games or looking through a microscope. Half of us who suffer from motion sickness will only succumb to an attack if the movement is quite noticeable — for example, riding in a boat when the water is rough as opposed to when it's calm.

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Here are some other risk factors for motion sickness [sources: University of Maryland Medical Center, Beck]:

Age: Motion sickness tends to strike kids the most, specifically those between the ages of 2 and 12. Once in their teens, many people outgrow motion sickness, but certainly not all. But if you suffer from motion sickness and make it to your 50s, you may finally get a reprieve, as this is when inner-ear function starts to decline. (We'll explain that connection on the next page.)

Gender and Race: Studies show women are more susceptible than men, and Asians more than whites or blacks.

Location: Sitting in the back of a car makes it worse than in the front (which is one reason some say children suffer more from motion sickness than adults.) Also, if the vehicle is not well-ventilated, that can also bring it on.

Certain illnesses and conditions: If you're pregnant, prone to nausea or vomiting, or are a nervous or anxious person, you're more likely to get motion sickness. Studies show that migraine-sufferers often develop it, as do those who sleep poorly.

Finally, research has also shown that experiencing this ailment could be genetic.

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The Science Behind Motion Sickness

Motion sickness happens when there's a discrepancy in your body's motion sensors. Your inner ear senses the way the waves are rocking the boat, but your eyes aren't detecting any movement.
Motion sickness happens when there's a discrepancy in your body's motion sensors. Your inner ear senses the way the waves are rocking the boat, but your eyes aren't detecting any movement.
Bonnie Schupp/E+/Getty Images

Scientists don't have all of the answers when it comes to motion sickness. What they widely believe is that the ailment strikes when there's a discrepancy between your body's motion sensors.

There are three different parts of the body that sense motion and relay that information to your brain: your eyes (they see motion), your inner ear (it senses motion, acceleration and gravity) and the sensory receptors in your skin, muscles and joints (they determine if you're moving your muscles and which parts of your body are touching the ground). If there isn't harmony between these sensors, motion sickness occurs [sources: WebMD, KidsHealth].

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So how can these sensors get scrambled? Let's say you're on a boat. Your inner ear senses the way the waves are gently rocking it, but your eyes aren't detecting any movement. This can cause motion sickness. Or perhaps you're watching the IMAX movie "Avatar." Your eyes are seeing motion as the movie makes it appear you're flying over the great land of Pandora. But your inner ear and sensory receptors are telling your brain you're sitting still. This causes confusion and can upset your body. Typical motion sickness symptoms include nausea, headache, dizziness, pale skin, cold sweats, increased salivation, fatigue and vomiting [source: University of Maryland Medical Center].

While scientists are pretty confident these sensory discrepancies cause motion sickness, they don't know why. The theory that our senses being at odds with one another is what causes these physical symptoms is mainly conjecture.

Some people are definitely more sensitive to motion than others. Studies indicate your heightened sensitivity could be genetic. Scientists also know motion sickness can only occur if we have our inner ear, the organ that senses motion. And while vision is often a major component in whether or not someone suffers from motion sickness, blind people can become motion-sick, so sight is not a critical factor [source: Kraft].

Another issue of study in the field of motion sickness is our stomachs. It appears reasonable that conflicting motion sensors can cause us to become dizzy. But why should that conflict cause us to feel nauseated and puke? One theory is that upchucking is tied into an evolutionary means humans developed to protect themselves from being poisoned. Some toxins that they consumed in the past attacked the inner ear. So, the theory goes, if our inner ear is feeling discombobulated, our bodies may have evolved to fear this means we ate something poisonous, so its built-in response is to make us throw up to get it out of our systems [source: Beck].

Besides the "senses out of harmony" theory, the other main idea as to what causes motion sickness is the "sway theory," which we'll look at on the next page.

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Preventing and Treating Motion Sickness

Put forth by Thomas Stoffregen, a University of Minnesota professor of kinesiology and director of its Affordance Perception-Action Laboratory, the postural stability theory, or sway theory posits that motion sickness has nothing to do with the inner ear. Instead, it's linked to our body's natural swaying and equilibrium.

Every person's body sways, or moves, to some degree when he or she is standing. It's impossible for anyone to remain perfectly motionless. Many of us don't realize we're swaying a bit, though, as the motion is generally just an inch or two in each direction. In addition, we've all learned how to maintain our balance — say, by pushing back with our toes if we're pitching forward a bit, or with our heels if we're moving backward.

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Now imaging putting your slightly swaying body on a ship or amusement park ride. You can't stabilize your body using the methods you've used all of your life — methods that normally work. That dissonance, that instability, is what causes motion sickness, says Stoffregen. So rather than motion sickness coming from conflicts among your body's motion sensors (eyes, inner ear, sensory receptors), it's occurring because you can't control your body's postural motion [sources: Beck, Stoffregen and Smart, Jr.].

Stoffregen also applies his theory to the fact that women are more prone to motion sickness than men. He notes males and females have similar bodies and swaying patterns before puberty. But once they mature sexually, their bodies become quite different, with women carrying more weight in their hips and men packing it in their chests. This difference in weight distribution makes them sway differently, with women swaying more slowly but farther. For women, that means an increased susceptibility to motion sickness. Stoffregen also claims a woman's tendency towards motion sickness can change along with her menstrual cycle. And with pregnancy. Pregnant women are at risk for motion sickness; Stoffregen says that's because pregnant women who suffered from morning sickness sway more [source: Smith].

Stoffregen published a study on the sway theory in 1998. For a long time, the idea was ignored but The New York Times reported in 2015 it is now gaining "grudging recognition."

It's unfortunate that so many of us succumb to motion sickness. But there are plenty of tricks for preventing and treating it. On the prevention side, one of the more common means is to take some kind of anti-motion sickness medication. Over-the-counter antihistamine pills (like Dramamine) are popular, as they make you drowsy which, in turn, makes you move less. The less you move, the better you feel.

You could also try scopolamine patches (brand name Transderm Scop); they can help by calming your inner ear's nerve activity. With any motion-sickness medication, the key is to take it well ahead of the time you travel. If you're popping pills when you start to feel queasy, it may be too late, as it's difficult to stop motion sickness once it's in, um, motion.

The best way to prevent illness if you're in a car is to be the driver, because then you can anticipate how the car is going to move, which enables your body to prepare for, say, a sudden, sharp curve to the right. If you can't be the driver, sit in the front seat, which also enables you to see looming movement changes. No matter what, don't sit in a seat that faces backward — because you need to see what's coming (rather than behind you) to feel better.

Also, don't read books, tap on your laptop or text on your phone in a car. The swaying words on the page or screen are sure to make you ill. It's also wise to eat something small before you travel so your stomach isn't empty. But no heavy meals, spicy or fatty foods or alcohol. Some people swear that downing gingery foods or drinks, or wearing an acupressure bracelet helps, although those measures haven't been scientifically proven effective. Finally keep your travel space well-ventilated and free of strong odors.

What if you forget to take your medicine, or can't resist poring over the latest copy of US Weekly, then suddenly start feeling ill? First, get some fresh air. Lying down might also help. If you can't do that, try to keep your head still. If you have access to food and drink, nibble on dry soda crackers or sip on a clear, fizzy drink (like ginger ale).

Another idea, especially if your motion sickness is on the mild side, is to chew gum. Or, actually, chew anything. It's the chewing action that helps, not the substance itself. Interestingly, motion sickness is rather suggestible. So if you see someone else becoming ill, look away. If a child appears to be getting sick, distraction often works.

Mind-body techniques, such as cognitive-behavioral therapy, biofeedback training and relaxation, and deep breathing can teach people who suffer from motion sickness how to avoid the condition or cope with it better [source: University of Maryland Medical Center].

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Author's Note: How Motion Sickness Works

I've suffered from motion sickness for as long as I can remember. My mom says it all started when I was an infant; I'd throw up anytime I was in the car. (Guess that means I was an early adopter; most people don't begin suffering until the age of 2.) Luckily, I've always been fine in planes. Boats, too, unless the water's exceptionally rough. I was fine on amusement park rides until recently — that may be more of an age thing than motion sickness.

I'm not sure what any of this means. But I'm suddenly looking forward to aging, in the hopes that as my inner-ear fluid dries up, or degenerates, or whatever, I've be provided with some relief.

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More Great Links

  • Beck, Julie. "The Mysterious Science of Motion Sickness." The Atlantic. Feb. 17, 2015. (Jan. 20, 20156) http://www.theatlantic.com/health/archive/2015/02/the-mysterious-science-of-motion-sickness/385469/
  • Gaskill, Melissa. "Motion Sickness Treatments Make Waves." Scientific American. Sept. 3, 2011. (Jan. 11, 2016) http://www.scientificamerican.com/article/motion-sickness-treatment/
  • KidsHealth. "What's Motion Sickness?" January 2014. (Jan. 10, 2016) http://kidshealth.org/kid/talk/qa/motion_sickness.html
  • Kraft, Sy. "Motion Sickness (Travel Sickness): Causes, Symptoms and Treatments. Sept. 8, 2015. (Jan. 10, 2016) http://www.medicalnewstoday.com/articles/176198.php
  • Paddock, Catharine. "Motion sickness effectively treated with mild brain stimulation." Medical News Today. Sept. 7, 2015. (Jan. 15, 2016) http://www.medicalnewstoday.com/articles/299132.php
  • Smith, Peter Andrey. "Rethinking Motion Sickness." The New York Times. Sept. 23, 2013. (Jan. 10, 2016) http://well.blogs.nytimes.com/2013/09/23/rethinking-motion-sickness/?_r=0
  • Stoffregen, Thomas and L. James Smart, Jr. "Postural instability precedes motion sickness." Brain Research Bulletin. Feb. 5, 1998. (Jan. 15, 2016) http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.541.1738&rep=rep1&type=pdf
  • University of Maryland Medical Center. "Motion sickness." (Jan. 10, 2016) https://umm.edu/Health/Medical-Reference-Guide/Complementary-and-Alternative-Medicine-Guide/Condition/Motion-sickness
  • WebMD. "How to Beat Motion Sickness." 2001. (Jan. 12, 2016) http://www.webmd.com/a-to-z-guides/features/how-to-beat-motion-sickness
  • WebMD. "Motion Sickness -- Topic Overview." Nov. 14, 2014. (Jan. 10, 2016) http://www.webmd.com/cold-and-flu/ear-infection/tc/motion-sickness-topic-overview
  • Williams, David. "Coping with travel sickness." The Telegraph. Aug. 10, 2011. (Jan. 10, 2016) http://www.telegraph.co.uk/motoring/caraccessories/8688774/Coping-with-travel-sickness.html