The inner ear perceives the up and down motion of the body riding on the ship, while the eyes perceive the random forward movement of the waves. Another type of conflicting message occurs when the inner ear perceives movement while the eyes detect no movement. This can occur while standing or sitting still inside a moving ship or vehicle with no windows to visually explain the movement. It can also happen when a person is trying to read when traveling in a car. The inner ear perceives the movement of the car but the eyes detect no movement.
Motion sickness is a normal response to an abnormal situation.
It indicates that the feedback system of the eyes, inner ear, and the brain is healthy. The most common symptoms of motion sickness are nausea and vomiting . A person may also turn pale in color, and break out into a cold sweat. An increase in oral secretions, yawning, fast breathing, headache , and drowsiness may also occur. Motion sickness, like that experienced on a ship, usually ends within 3 days of traveling.