What Causes Seasickness?
Seasickness is a form of motion sickness characterized by a feeling of nausea experienced after spending time on a ship. It is caused by the unfamiliar pitching motion of a ship’s deck. Inside the inner ear is a fluid-filled organ called the semicircular canal, which is the organ of our sense of balance.
It enables us to keep our balance when we stand, walk or run. But the uneven movements of a ship’s deck upset the sense of balance organ. The motion causes it to send confusing messages of balance to the brain, and we may feel dizzy and nauseated.
Some people also experience motion sickness when traveling by car or plane. Most people tend to concentrate on the inner surroundings, or close the eyes and try to sleep. This will cause the worst effect of the disturbance.
The brain receives conflicting signals: while the eyes show a world that is still, our body, and in particular the equilibrium sensors located in our ears, send signals of a moving environment. This discordance causes the mind to send to the whole body a general alarm signal, in order to stop all activities, in particular the most complex of all, the digestion process.
Generally, the disturbance will cease once the visual and motion stimuli are synchronized. This can be obtained by concentrating on the horizon until things appears fixed and horizontal. This is the signal that our vision has switched from the reference system of the boat to the reference system of the earth.