Reply #158: He was on LSD while writing the novel

[Susang]

When I was in college, I attended a lecture given by Kesey. In that lecture, he basically said he was tripping most of the time he was writing Cuckoo's Nest. He felt LSD was the only way he could understand what it was really like to be schizophrenic.

This was the only verification I could find of that comment at 3:00AM. ;-)

Kesey’s interest in altered consciousness led him to accept a position in a mental hospital. While the job allowed him ample opportunity to write uninterrupted, it also introduced him to several individuals who would serve as models for characters in One Flew over the Cuckoo’s Nest. Kesey also ingested LSD (called “tripping”) while interviewing the patients in order to gain insight into their altered perceptions of the world. He even convinced a friend to administer electroshock therapy to ensure an accurate depiction in his novel.

Cuckoo’s Nest conveys Kesey’s interest in altered consciousness, particularly in the voice of the narrator, Chief Bromden. The paranoid sections of the novel where Chief discusses his belief that the hospital where he stays is actually an emasculating factory for a larger Combine that represses individuality were largely written while Kesey was under the influence of mind-altering substances.
http://education.yahoo.com/homework_help/cliffsnotes/one_flew_over_the_cuckoos_nest/1.html