This is also a very common problem and is caused by motion of the vehicle in which one is traveling. Moreover, this sickness occurs and starts when sensory organs (inner part of ear) are not able to provide balanced information to the brain.
Its nothing but a stress and our central nervous system react to it, which causes nausea in the brain.
Symptoms of this sickness are well noticed, sweating, dizziness, vomiting, or drowsiness. However, this is not a very serious problem and can be controlled by some common medicines or by getting used to the motions while traveling. Although this type of sickness is very commonly, seen in hilly areas where roads have lot of turns and twists.
While tension, stress, depression and other mental problems can aggravate it; this disorder can be cured easily.