Danny DeVito Was So Stressed While Filming ‘One Flew Over the Cuckoo’s Nest’ That He Talked to an Imaginary Friend and Consulted a Psychiatrist

Actor Danny DeVito has appeared in more than 90 films over the years. And with all those movie experiences come some pretty intense on-set stories. One of his most iconic films, One Flew Over the Cuckoo’s Nest, also happened to be one of his most psychologically damaging.

The 1975 film earned critical acclaim and a slew of Academy Awards. But it also had a profound effect on the actors during production. DeVito admits he spoke to an imaginary friend and sought out psychiatric help.

The brutal conditions on the set

Directed by Milos Forman as an adaptation of Ken Kesey’s novel, One Flew Over the Cuckoo’s Nest set the story in a 1960s mental institution. Stars like Jack Nicholson, Michael Berryman, and Louise Fletcher brought legendary characters to life, including the frightening Nurse Ratched. If you haven’t seen this historic top pick, the plot revolves around a criminal who pleads insanity and finds himself in an insane asylum where he rebels against his nasty nurse and rallies the other patients.

It might sound like a scary environment. In fact, the filming of this hit movie took place in an actual institution, where the lights go out at 3 p.m., and real patients participated in the film’s production. The Oregon hospital’s director, Dr. Dean Brooks, even appeared as Nicholson’s character’s supervisor. 

This made a brutal environment for the actors, who weren’t aware that some of the patients involved were violent criminals. In fact, some of the cast even slept in the wards. In an interview with The Guardian, producer Michael Douglas shared that they filmed some scenes without the actors’ knowledge, including mock group therapy sessions, to inspire organic character development.

Danny DeVito questioned his sanity during ‘One Flew Over the Cuckoo’s Nest’

Danny DeVito
Danny DeVito | Axelle/Bauer-Griffin/FilmMagic

Several reports convey the effects the production of One Flew Over the Cuckoo’s Nest had on the cast. And DeVito, who is also a producer and director, was no exception. He was the first actor cast, playing the character Martini. It didn’t take long for the brutal on-set environment and the job of playing a person with a mental health condition to impact the Twins actor.

History By Day wrote the rigorous shooting schedule kept DeVito 3000 miles away from his then-future wife, Rhea Perlman. Needing a coping mechanism, DeVito reportedly developed an imaginary friend with whom he held nightly chats.

As production continued, DeVito became increasingly concerned about his mental health. He sought out the advice of the real-life Dr. Brooks to help him not blur the lines between reality and his Martini character.

Sydney Lassick experienced behavioral changes, too

DeVito and his acting colleagues all experienced a degree of mental uncertainty during filming. But some said Sydney Lassick actually had the crew worried. Dr. Brooks even expressed his concern for Lassick’s mental stability. Lassick’s role as Charlie Cheswick remains one of the most notable of his career.

Lassick demonstrated a growing unpredictability with his emotions on-set. When he was in character, he often experienced tearful outbursts. And one of the most concerning moments occurred when filming the final scene. Lassick began sobbing to the point that he had to be physically removed from the set altogether.

Method acting and developing characters organically is a common practice for professionals on-set. But looking back at the conditions of the production environment for One Flew Over the Cuckoo’s Nest proves such methods could have adverse effects. DeVito had to seek psychiatric help and talk to an imaginary friend to get through filming. And it reminds fans that acting can sometimes be a pretty terrible job for even the biggest stars.

RELATED: How Danny DeVito Almost Died On ‘It’s Always Sunny’