|MadSci Network: Medicine|
Seasickness is all in the head. Actually it's in the ears. There is a complex of three fluid-filled canals in each ear that communicate with the brain and eyes to help us maintain our balance. Out on the water in a boat these canals send many more messages than the brain is used to, from the constant bobbing around. There is so much movement that the brain gets confused and nausea results. Like any other organ, however, with time, the brain gets used to the complex, multiple messages and gets used to the increased number of signals and the seasickness goes away. This, of course, varies from person to person and can take from days to weeks to get better.
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