Why some people get motion sickness—and others don’t
Popular Science...
A couple of years ago, I found myself traveling along the Drake Passage to Antarctica when our ship encountered a patch of 15-foot-tall swells. Waves were slamming against the exterior of our vessel, causing nauseated passengers to run to their rooms and stay there. By the end of the afternoon, at least two-thirds of us were suffering from motion sickness. The others? To them, it seemed that all of the rocking and rolling was just another fine day at sea.
“Everyone is capable of motion sickness,” Dr. Kristen K. Steenerson, a clinical associate professor at Stanford University School of Medicine who specializes in inner ear and balance disorders, tells Popular Science. “It’s just that everyone has different thresholds for how much motion exposure is stimulating enough to make them sick.”
For some people, it might be the simple movement of an iPhone camera when FaceTiming with your 83-year-old father. For others, it’ll take the pounding waters of one of the world’s most turbulent seas. Still others might need seven days crossing Atlantic waters to even feel slightly seasick (a form of motion sickness). Popular Science turned to Dr. Steenerson to find out what makes one person more susceptible to motion sickness than another, and learn how we can mitigate the effects.
What is motion sickness, and what causes it?
Motion sickness is a temporary condition that can come on quickly, and is typically triggered by the movement of cars, boats, planes, trains, and amusement park rides, such as roller coasters and Tilt-a-Whirls. Some people can get motion sick on a playground swing; others might feel it on a surfboard. Symptoms include everything from nausea, cold sweats, and headaches, to vomiting, pale skin, and dizziness.
When a person feels motion sickness coming on, it’s usually because they’re experiencing a sensory conflict or neural mismatch. That is, when the brain receives conflicting signals from three peripheral sources which are essential for maintaining balance. These are the eyes, the inner ears, and body sensors in our joints, muscles, and tendons. The latter is known as proprioception, or a body’s ability to sense its own movements and actions. For example, the ability to type without looking at the keys or discerning how much pressure to use when holding an egg.
“The brain takes different sensory bits of information from all three and then combines those together,” says Steenerson, “integrating them, if you will, into one cohesive message.”
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When what your eyes see matches with what your ears detect and your joints feel, things tend to run smoothly. Your body feels oriented and you have a normal sense of motion. It’s when they’re not lining up perfectly that your brain, and in turn your nervous system, starts stressing out.
“The brain gets conflicting signals and it doesn’t know what to do so it acts as a sort of cascade effect, irritating neighboring structures in the brainstem and throwing everything off balance,” says Steenerson. Your body then reacts to this sensory confusion accordingly, trying to purge any perceived toxins.
“There’s a theory that motion sickness evolved from people being poisoned,” says Steenerson, “because poisoning causes a sensory mismatch as well. The brain gets confused and says, ‘you know, let’s try and get rid of everything just in case.’”
How common is motion sickness?
It’s actually very common. About one in three people are considered highly prone to motion sickness, though some people undoubtedly have it worse than others.
Age, genetics, and environmental factors like poor ventilation and strong odors, like cigarette smoke, all play a role in the severity of motion sickness. In fact, some studies show that up to 70 percent of the variation in motion sickness susceptibility is inherited.
“Kids are much more susceptible,” says Steenerson, “and then us lucky women who are premenstrual, perimenopausal, or post-menopause can also become more susceptible,” as well as pregnant women, thanks to fluctuating hormone levels, specifically estrogen.
Generally speaking, you experience more motion sickness when you’re young (children between the ages of seven and 12 are the most susceptible), and less as you grow into adulthood. The chances of dealing with motion sickness increases again in our later years, due to the fact that the inner ears’ motion sensors degenerate with age. People prone to high anxiety or migraines can also be at a higher risk for motion sickness.
There’s also a form of motion sickness known as sopite syndrome, which is characterized by intense drowsiness, mood changes like depression, irritability, and apathy. It often affects people such as sailors, astronauts, and aviators who are exposed to long and repetitive motions: those who have seemingly adapted to motion sickness (e.g. they don’t get nauseated or dizzy), but can’t seem to shake the fatigue.
What can help mitigate the effects of motion sickness?
While motion sickness is a tough pill to swallow, there are numerous ways to reduce symptoms.
“A lot of people avoid eating because they think ‘I’m gonna get nauseated, I don’t want to throw up.’ It’s actually the opposite,” says Steenerson. Eat a little bit of food, but avoid heavy meals—particularly spicy ones—because they could upset your stomach. Avoid drinking alcohol, which can leave you dehydrated and worsen the effects of motion sickness.
Try focusing on a stationary object if you’re in a moving vehicle to reduce any sensory mismatch, or find ways to minimize the feel of movement. For example, sit in the front of a car as opposed to the back seat—where the rear wheels can feel jarring—or choose a seat looking out over an airplane’s wing, which is closer to the plane’s center of gravity. If you’re traveling on a ship, situate yourself in the middle of the vessel on a deck closest to the water. It’s one of the steadiest spots onboard. Backward-facing seats can also cause sensory mismatch: opt for front-facing seats on buses and trains.
If you do want to take medication for motion sickness, says Steenerson, it should be taken an hour to several hours before, depending on what you’re taking. “If you’re already motion sick, you’ve missed your window,” she says. Fresh air, ginger chews, and ginger ale (ginger can alleviate upset stomachs by blocking nausea-inducing signals in the brainstem) are also helpful when it comes to curbing motion sickness. Another trick is having touch points, such as laying on a bed or pushing your head against the seat when you’re on the airplane, to help offset any confusion between your eyes and ears.
Oddly, listening to music can be really helpful. “There’s a study showing an over 50 percent decrease in motion sickness if you’re playing soft music,” says Steenerson.
You can also try and train your brain through habituation, the process of doing something over and over again until you build up tolerance. For example, reading for five minutes in a car and slowly increasing the length of time each time you do it.
Managing, adapting, and adjusting
Whether you’re slightly dizzy when stepping out of a car or ready to puke during rough Antarctic seas, motion sickness is very real and very common. But don’t let it keep you from embarking on that road trip or scoring your seventh continent.
“Most motion sickness is probably coming from your brain,” says Steenerson, “so healthy brain habits do matter.” Rest up, stay hydrated, and arm yourself with Dramamine, ginger chews, and ample acoustic tunes.
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