travel sickness

Nausea and vomiting caused by the motion of cars, boats, or other forms of transport. Constant vibration and movement may stimulate changes in the fluid of the semicircular canals (responsible for balance) of the inner ear, to which the individual fails to adapt, and to which are added visual and psychological factors. Some proprietary remedies contain antihistamine drugs.

Space sickness is a special case: in weightless conditions normal body movements result in unexpected and unfamiliar signals to the brain. Astronauts achieve some control of symptoms by wedging themselves in their bunks.