For many people, summer means vacation, and vacation means travel. Travel usually involves some kind of locomotion -- whether by plane, train, automobile, or boat -- to get from home sweet home to a fun destination. Therein lies the rub for people with motion sickness.
"Nearly everything that moves will make me ill," says Andrea Messer, who has suffered from motion sickness since she was an infant. "Every instance of motion, except when I am in control of whatever is moving, makes me sick. So if I am the driver, that's fine; if I am rowing the boat, that's fine. Otherwise ..."
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Though most people aren't afflicted as severely as Messer, chances are good you've experienced some kind of motion sickness at one point or another. "All of us could get motion sickness under the right conditions," Robert M Stern, PhD, tells WebMD.
Stern, distinguished professor of psychology at Penn State University, has studied motion sickness for the past 15 years. He and colleagues think motion sickness is caused by a "sensory mismatch."
Normally, a million times a day the vestibular system, the body's system to help regulate balance and motion, and the vision system send corresponding signals to the brain, explains Stern. "Anything that disrupts that normal relationship is what we think leads to motion sickness," he says.
"In a car, in the typical American family, the father drives, the mother sits up front, and the kids are in the back," Stern says. "That poor little kid, all he can see is the back of the front seat. To the child's visual sense there is no motion involved -- the back of the front seat is always the same distance from him, but through the vestibular system in the inner ear, he's getting all the turns in the road, the acceleration, etc."
The same holds true for reading in the car. "Your eyes are seeing the page 10 inches in front of you -- that is never changing -- but your vestibular sense is picking up all of the movements," Stern says.
Interestingly, some ethnic groups seem to suffer from motion sickness more than others. Stern says that in his research, he found Asians are much more susceptible to motion sickness than whites or blacks. "That suggests there are genetic factors at work," he says.