What causes motion sickness—and how to avoid it

When our mind's eye meets tech, the result can be cold sweats or queasiness.
A car passenger appears to feel nauseous with her hand to her mouth.
Passengers are more likely than drivers to feel motion sick, probably because they're not in control of the vehicle. Depositphotos

Back in the late 19th century, some thrill-seekers got their kicks by riding what was called a haunted swing. This appeared to be a normal room, furnished with a table, chairs, and, in at least one case, a piano, but there was a trick: Suspended from an iron beam across its middle were several seats on a swing, a bit like the pirate-ship-shaped gondolas found at modern carnivals. After making the seats sway to-and-fro as expected, an attendant would stop the swing and spin the entire room around the riders (all the furniture was bolted to the floor). Part of the crowd was delighted; the rest wanted to puke. 

As one visitor to the 1894 Midwinter Fair in San Francisco put it: “Many persons were actually made sick by the illusion. I have met a number of gentlemen who said they could scarcely walk out of the building from dizziness and nausea.” What they were feeling was a form of motion sickness, brought on by the mismatch between the stillness of their seated bodies and the world whirling around them.

Motion sickness is an illness that’s exclusively triggered by technology. It hits when we feel at rest inside a vehicle in motion, making us carsick, seasick, or airsick—but can also happen with some amusements or optic devices. The haunted swing may have caused what today’s experts call visually induced motion sickness, or VIMS, a sensation that can occur while wearing a VR headset or sitting in the front row to watch Avatar or another 3D movie. Either version of the conditions can produce similarly nasty or gut-churning effects.

Symptoms and causes of motion sickness

The two most prominent effects of motion sickness are nausea and vomiting. Queasy sensations usually come first, but it’s possible to have one without the other—some motion-sick people throw up without much warning. Symptoms also include feeling flushed (without any actual increase in body temperature), dizziness, disorientation, headaches, loss of appetite, lots of salivating, and cold sweats.

Generally speaking, there are two main ideas for how this illness arises: the “postural instability theory” and the “sensory conflict theory.” The first proposes that, as we lose control over our posture, as when at the mercy of a wave-rocked boat, we’ll get sick. The second, more often cited in medical research, explains that we become unwell because of the discrepancies between our sensory systems and our brains’ blueprints for how things ought to be. The haunted swing is a “classic example of sensory conflict,” says John Golding, a professor of applied psychology at the University of Westminster, in London, who has been studying motion sickness since the late 1980s.

As our bodies move through different spaces, our brains save patterns of what that should feel like. When we twist our heads, for instance, our eyes give us visual cues, but there are other systems at work. Our muscles, joints, and vestibular system register the movement, too. That sensory network, which is responsible for maintaining balance and orientation, includes the brainstem and inner ear. 

[Related: How to fight motion sickness while gaming]

This is relevant for one important reason. Our brains are “like an archive,” able to “pick out and compare” what we’re experiencing now to past perceptions, says Behrang Keshavarz, who studies virtual reality and motion sickness as a senior scientist at the University Health Network’s KITE-Toronto Rehabilitation Institute in Canada. If our bodies’ sensations match each other—if the eyes and vestibular system line up—and our minds’ expectations follow along, great. If they’re slightly off, it’s probably fine. But when there are big differences in how they all sync up, the unpleasantries kick in. Surprisingly, the physical intensity of a movement doesn’t seem to influence the onset of this illness. “You don’t get horse-sick,” Golding says, no matter how vigorously the animal hoofs it. “You can get quite sick with more gentle types of motion.”

If we can become queasy so easily, is there an evolutionary explanation? It’s unclear, but some experts have proposed a “toxin theory” where “what we call motion sickness is simply the aberrant elicitation of a very ancient defense reflex,” Golding explains. Put another way, our dizzy brains think we’re being poisoned and force us to puke to expel the offending substance.

Some people are more susceptible to motion sickness than others. Golding’s research has found that those who experience migraines are more likely to experience the illness. There may be clues buried in our genetic material, but that research is in its early stages. One of the few DNA studies, conducted by genomics company 23andMe, identified at least 35 different genetic variants associated with car sickness. Golding likens this finding to the bell curve of height seen across human populations—there’s no one gene responsible for how tall we grow, but thousands of contributors

Age and biological sex could play a role, too. Babies under a year old rarely get motion sickness, but incidence peaks around 8, then decreases into adulthood. That could be different for VIMS, where people older than 65 are more likely to feel sick in a driving simulator, for instance. Meanwhile, some studies indicate that female individuals tend to experience motion sickness more than male individuals. But Keshavarz, who is also an adjunct professor in the Toronto Metropolitan University’s psychology department, says his work and other experiments have failed to consistently find a sex difference. 

Prevention and cures for motion sickness

The best way to handle motion sickness is to avoid what causes it, whether that means avoiding boat rides if you get seasick or helicopter tours if you feel airsick. The Centers for Disease Control and Prevention also recommend passengers stay hydrated in transit, have frequent light snacks, avoid smoking, limit alcohol or caffeine, sit at the front of a car or bus, pick a window seat, and lie down or close their eyes if possible. 

[Related: Does ginger ale work for motion sickness?]

As a more general strategy, it helps to anticipate changes in motion. Being in control of the vehicle reduces the likelihood of motion sickness: Drivers are less likely to get sick than passengers, for example. Or focus on getting your bearings. “On the whole, if you can get a stable horizon view, you’re better off,” Golding says. (Reading a book or scrolling on a phone, on the other hand, can worsen things, because we’re shifting our eyes to stationary objects that don’t indicate we’re in motion.) Finally, some techniques can remove the trigger that is causing the sickness. As a rider of the haunted swing wrote in 1895, “The minute the eyes were shut the sensations vanished instantly.” 

It’s possible to treat symptoms of motion sickness with medications like diphenhydramine (sold under the brand name Benadryl), dimenhydrinate (Dramamine), or scopolamine, but these can also cause unwanted drowsiness. Golding’s behavioral studies have also found that controlled breaths—when “you concentrate on keeping your breathing very, very regular”—can relieve motion sickness; it’s about half as effective as medication, though without any side effects. And while there’s not much evidence that acupressure bands actually prevent nausea, wearing one on the wrist could provide psychological relief, Golding adds. “Placebo effects can be quite strong.”

Keshavarz has studied whether pleasant scents or sounds can reduce VIMS, and has found that listening to a favorite genre of music can be helpful in some circumstances. He’s currently examining whether changes to body temperatures have an effect, based on previous experiments with increased airflow exposure. “My hypothesis is that it cools the body and makes you feel better,” he says, counteracting the sensation of being flushed. But, overall, Keshavarz expects motion sickness to remain a problem as our dependency on technology grows. With driverless cars, self-driving air taxis, and shiny new VR products coming down the pike, it could mean more opportunities to lose our lunches.