Voluntary nystagmus

How it works

Nystagmus is a repeated, rhythmic movement of the eyes. It usually happens by itself, as a result of an inner ear or brain problem. Voluntary nystagmus is different. A small group of people can switch it on and off at will¹.

The movement is a stream of very fast, very small eye jumps, one after another, left and right². Each jump is a saccade, the same kind of movement your eyes make when you read. In voluntary nystagmus the saccades are packed so close together that the eyes appear to vibrate.

People who can do it describe the same method. They cross their eyes slightly and tense the eyes, as if straining to focus¹. The shaking starts on its own. It is hard work. Most people can keep it going for 5 to 30 seconds before the eyes tire¹. Vision blurs while it lasts.

Between 5% and 8% of people can do it¹. It runs in families and is often discovered in childhood. It causes no harm. Eye doctors know it well, because a few patients use it to fake an eye disease.

Try it

1. Sit in front of a mirror or turn on your phone camera.
2. Hold a finger close to your nose and look at it, so that your eyes cross a little.
3. Tense your eyes as if squinting hard, but keep the lids open.
4. Watch for a fine, fast shake. If you see it, try to hold it for a few seconds.
5. Stop if your eyes ache. Nothing is gained by pushing.

If nothing happens after a few tries, you are probably in the majority. There is no known way to learn it.