We become sea-sick because our balancing organs, the labyrinthine portions of the inner ear, are disturbed by out-of-level movements, by sudden turning movements, or by sudden changes in movements in a straight line, either horizontal or vertical.
The ear has three semicircular canals, filled with fluid and set on different planes in the ear. When sudden movements occur, each canal is affected differently. As a result, nerves in the canals send conflicting information to the brain, so giddiness is likely to occur.
Nowadays, seasickness comes under the general heading of motion sickness a name invented by Sir Frederick Banting in 1939, which include the discomfort people feel while travelling in all kinds of vehicles.
Sea-sickness may vary with individuals from slight uneasiness to complete prostration. The symptoms are pallor, cold sweating, nausea and vomiting. People who have lost their ear labyrinths because of disease do not become seasick. Others become resistant to it. We say they develop their “sea-legs”, but it would appear to be an adjustment of the central nervous system rather than the organs of balance. Some people find it helpful to keep their gaze firmly fixed on a steady object.
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