T.S. Eliot composed much of The Waste Land inside of a Swiss mental institution, where he was recovering from a nervous breakdown.

Ezra Pound was similarly committed to St. Elizabeth's after World War II.

George Orwell was admitted to a sanitarium years before he wrote either 1984 or Animal Farm.

Fyodor Dostoyevsky was frequently plagued by demons that he tried to escape through drink and gambling.

Eugene O'Neill suffered from depression and was deathly afraid that he had inherited from his mother what his entire family had assumed was mental illness.

Both Martin Scorcese and Francis Ford Coppola made two of their greatest films when they were emotionally bankrupt, financially destitute and when friends were questioning their psychological stamina.

The idea of the artist as madman is so frequent as to be a cliche, but some stereotypes do exist for a reason: Vincent Van Gogh, Francisco Goya, Michaelangelo.

source: everything2.com