9 Brain Disorders That Completely Warp Your Reality

4. The Glass Delusion: If I Move I Will Shatter

One of the weirdest things about certain brain disorders, is that they seem to be subject to "fashions". The glass delusion is one such disorder, with a massive surge in prevalence from the 15th to the 17th century, followed by a rapid decline.

As the name suggests, sufferers of the glass delusion are convinced that they are made of glass and become increasingly anxious that they might smash.

Arguably the most famous glass delusionist was King Charles VI of France. Some modern historians and psychologists have tentatively diagnosed the king and his son with schizophrenia, and he regularly suffered from fits of rage, paranoia and anxiety. He would also sit, motionless, for hours at a time and was convinced that if he moved he would shatter.

The condition spread through the population and was prevalent enough to be referenced by everyone from Descartes to Cervantes and then, after 200 years, it stopped. There were occasional isolated cases in the Victorian and modern eras, but to this day, nobody is quite sure how a disorder can simply seem to vanish.