How does the body adapts to seasickness?
In: Biology
Sea sickness happens because the organs that sense balance and motion in your inner ear don’t agree with the other sensory inputs to your brain and your brain gets confused. So you adapt to it(a quick search says at least 75% of people eventually adapt) because your brain gets used to the mixed inputs and accepts it as a new normal. This is why people can get sick or dizzy again when they get off a boat after a long trip, because their brain learned to block out the motion. It is the same concept as your nose being in your field of vision but your brain ignores it.
The long answer is the vestibular system in your inner ear is cool as hell. We basically have a gyroscope and accelerometer built in to our inner ears. You have a few loops and a few sacs in the inner ear. They are all full of this thick liquid that has a bunch basically little crystal rocks suspended in it. The cells that make up the sacs have stuff “hairs” sticking into the liquid. When your body moves momentum makes it so that the little rocks in the liquid move and hit the hairs and then this gets translated into an oh I’m moving signal for the brain.
The sacs mostly tell about acceleration and gravity and help your body know that it is moving. There are 3 loops and each one is oriented in a different plain, x, y, or z. The same hairs and rocks in them tell you if you are nodding or shaking your head, or tilting it to the side like a confused puppy. And based off the input from all 3 rings your body knows which way you are moving your head, same basic idea as a gyroscope. And all of this data gets sent to the brain.
Now your brain doesn’t rely on just the inner ear. It has a ton of other data in. If your ear says you are tilted to the side but your neck muscles aren’t causing you to tilt your head your brain can infer that you are laying in your side. If your brain feels your body dropping down but your eyes and legs let it know you are walking down stairs it doesn’t freak out. But, when there is one more step than you thought and you start dropping again you have that mini heart attack because your ear senses falling and your brain doesn’t think you should be any more. When you soon in circles long enough the liquid in your ear starts moving at the same speed you are spinning, then when you stop the liquid keeps moving and now your brain thinks you are spinning the other direction because either hairs are being pushed by the moving liquid. But all your others body senses say you aren’t moving. So your brain is fighting a few different inputs and cannot control your body as well.
Sea sickness is, and most other motion sickness, is just a prolonged version of this. You are standing on the deck of a ship. Your brain isn’t moving any part of your body but your ear senses your body moving up and down due to the waves. This mismatch of signals to the brain messes up it’s function and you get a sick feeling because of it. For most people given time the brain learns that the new motion signals from the inner ear are just what happens now that you are on a boat and it can save this information as normal. Then your body is no longer sending mixed signals to your brain and you are no longer sick.
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