Human Body

Motion Sickness: What is it & Why do people get it?

What is Motion Sickness?

Motion sickness is the sense of unease you feel when the motion sensed by the inner ears is different from the motion sensed by the eyes. Most people experience motion sickness while traveling (car,bus,plane,boat) or in a roller coaster. The sense of unease gradually progresses to dizziness & nausea.

What causes motion sickness?

The brain senses motion through signals coming from three different pathways of the nervous system:

  • Inner Ears
  • Eyes
  • Body Surface

During intentional movements, for example, walking, the input from all three pathways is synchronized. In case of unintentional (as in a car or boat)  or complex motion (motion in multiple directions as in a roller coaster), there is a conflict in the inputs. The signals sent by inner ears don’t match with the ones sent by the eyes. As a result, the brain is not able to coordinate. This leads to change in levels of certain neurotransmitters that causes the symptoms of motion sickness to show. Experiments show that the inner ears have a greater contribution in sensing motion as compared to the ears & body surface. In the inner ear (which is also called the labyrinth), motion sickness affects the sense of balance and equilibrium. Hence the dizziness.

Body experiences motion in horizontal & vertical directions, leads to nausea
Complex motion in a giant wheel: Body experiences motion in horizontal & vertical directions.

How is motion sickness different from sea sickness?

There is no difference between motion sickness and sea sickness. Some people experience nausea when travelling in an airplane, automobile, or amusement park ride. This condition is referred to as motion sickness. Many people experience motion sickness when riding on a boat or ship. This is commonly called sea sickness , even though it is the same disorder.

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