The symptoms associated with motion sickness are believed to be caused by conflicting signals to the brain. Normally, the sense of motion is determined by learned expectations of sensory signals to our brain from the inner ear, muscles, tendons, and joints of the body. In motion sickness, a discrepancy exists between expected sensory stimuli and those that are actually perceived by the brain. These unexpected signals translate into a confused message by the brain, leading to the development of symptoms. Generally, symptoms disappear once the brain adapts to the new pattern of motion.
Motion sickness can occur in just about any mode of travel.
Although travel by boat often produces the worst symptoms, motion sickness is also common in people who travel by car, train, or airplane. Symptoms can even occur when traveling on an animal. Motion sickness is more likely to occur when riding a camel than a horse. Children appear to be more susceptible to motion sickness than adults. And women are more likely to develop the symptoms than men.