What Makes You Dizzy When You Spin?

If you have ever spun around like a top or rolled down a hill, then you have probably experienced dizziness or vertigo. Some people even get dizzy just getting up too fast from the sofa. When you become dizzy, a part of your body that senses motion has sent the wrong signal to your brain. An amazing system in your inner ear is the key to dizziness.

The body senses whether it is upright or lying down or whether it is moving or standing still through the vestibular system, which is in the upper portion of the inner ear. 

Vestibular system contains a number of parts, of which the most important are:A fluid called endolymph and hair-like sensory nerve cells. 

What Actually Happens??

1.   As your head moves in a given direction, the endolymph lags behind because it resists a change in motion (the principle of inertia).

2.   The lagging endolymph stimulates hair cells to send nerve signals to the brain.

3.   The brain interprets them to know which way the head has moved.

When you spin, the endolymph slowly moves in the direction you are spinning. The movement of the endolymph signals the brain that the head is spinning. The brain quickly adapts to the signal because the endolymph begins to move at the same rate that you are spinning and no longer stimulates the hair cells. However, when you stop spinning, the endolymph continues to move and stimulate hair cells in the opposite direction. These hair cells send signals to the brain. The brain determines that the head is still spinning, even though you have stopped. This is where the dizzy feeling comes from. Eventually, the endolymph stops moving, no signals are sent to the brain, your brain determines that your motion has stopped, and you no longer feel dizzy.

Try This Experiment Out

1.   Spin around 5-10 times rapidly to the right and stop. When you stop, you will feel slightly dizzy as described above.

2.   When you have recovered, repeat step 1, but when you stop this time, immediately spin the same number of times to the left and stop. You should now find that when you stop, you do not feel as dizzy.

In the second situation, you have begun to move the endolymph in opposite directions and the two effects of motion tend to cancel out.