The Mad Hatter’s Tea Party, from ‘Alice in Wonderland’ by Lewis Carroll (1832-9) (color litho) by John Tenniel

About 20 minutes before the onset of pain from a migraine headache, many suffers experience a phenomenon called “the aura.” During this time the sufferer may see intense colors, flashing lights, and even hallucinations such as monsters and ghosts. Lewis Carroll, who suffered from migraines for most of his life, is said to have been inspired to create some of the characters from Alice in Wonderland from the visions he saw during the aura.

These states of altered consciousness are called Alice in Wonderland Syndrome.

source