The title stems from an ancient practice of dealing with the mentally ill where they were thrown into a pit of snakes. The theory was that something like that would make a normal person insane, therefore it must work in reverse.
Mary Jane Ward's book, the basis for this film, was an autobiographical account of the author's experiences in psychiatric hospitals. The book caused considerable controversy upon its publication in 1946, as it was a scathing indictment of the treatment of psychiatric patients, a subject considered taboo in the 1940s. Naturally, the book was a runaway bestseller.
Director Anatole Litvak insisted that the cast and crew spend three months visiting mental institutions and attending psychiatric lectures to prepare themselves for the film. Olivia de Havilland willingly threw herself into the research. She attended patient treatments at the institutions, and observed electric shock therapy and hydrotherapy first-hand. When permitted, she sat in on doctor-patient therapy sessions. She also attended social events for patients at the institutions. After seeing the film, a "Daily Variety" columnist questioned whether any mental institution would really allow violent inmates to dance with each other at a social event. De Havilland personally called the columnist to confirm that she had attended several such dances at institutions.
Stephen King has said that watching this film on TV as a child deeply disturbed him and made him feel that he could suddenly go insane, directly contributing to his macabre interests and subsequently his writings.
The character of the gentle psychiatrist was based on the real-life career of Dr. Gerard Chrzanowski, who told his patients to call him simply "Dr. Kik." Dr. Chrzanowski died in November, 2000 at age 87.
In his autobiography, writer Arthur Laurents said that he had been hired by director Anatole Litvak to rewrite the first draft of the screenplay by Frank Partos and Millen Brand, which he did. Partos and Brand wanted the WGA to rule that they were the only writers and to delete Laurents' credit, so they submitted the script to an arbitration and presented carbon copies of Laurents' work as their own. The WGA removed Laurents' credit, even though several years later Brand admitted to Laurents that he and Partos had created forged carbons to make Laurents' work look like theirs.
The New York Film Critics awarded Olivia de Havilland Best Actress for the film. It was the first time since the awards' inception in 1935 that a performer won unanimously. And, as of 2014, the only time.
Ginger Rogers wrote that she turned down the lead in this film, as well as To Each His Own (1946), both of which Olivia de Havilland accepted. Olivia won an Oscar for "To Each His Own" and was nominated for this film. Rogers wrote: "It seemed Olivia knew a good thing when she saw it. Perhaps Olivia should thank me for such poor judgment".
The portrait on the wall in Dr. Kik's office is of Sigmund Freud. Although his influence has waned somewhat with the rise of neurological and biological research, during the filming of this movie Freud's theories were by far the most prevalent and influential of any psychiatrist, particularly in America. Thus, it was fashionable and quite common for psychiatrists to have either a portrait, picture or sometimes even a bust of Freud in their office.
Anatole Litvak scheduled the hospital scenes first in the shooting schedule, then gave Olivia de Havilland a month-long break before filming the flashbacks. For the hospital scenes, he gave orders that none of the actresses playing patients were to wear brassieres or girdles. He also forbade them to go to the hairdressing department. To make her character look suitably ill, de Havilland went on a diet designed to take her below her ideal weight.
Although publicity and some later accounts claim the film was shot almost entirely at Camarillo State Hospital in California, there were only a few location scenes shot there. Most of the interiors were shot on the 20th Century-Fox lot.
Ads during the film's initial run warned parents that the film might not be suitable for children. New York Times film critic Bosley Crowther seconded that opinion and in one column suggested the film only be shown in smaller theatres. Fox did not follow his advice.
In the novel, Virginia suffers from an undefined neurosis and receives unspecified treatment, while in the screenplay, she is described as a schizophrenic with an Oedipal complex who undergoes a range of treatments.
In an interview, Olivia de Havilland described her research: "I met a young woman who was very much like Virginia...a schizophrenic with guilt problems. She had developed...a warm rapport with her doctor, but what struck me most of all was the fact that she was rather likable and appealing...it was that that gave me the key to the performance."
Although Fox's ads for the film linked it to Gentleman's Agreement (1947) as a pioneering social problem film, posters also tried to created a romantic angle with the line "Married and in Love...with a Man She Didn't Know or Want!"
The film was held back from distribution in England for a year because the British Board of Film Censors forbade films dealing with insanity. Initially, efforts to soften that stand were fought by nursing organizations, who feared the film would discourage young women from going into that profession. Finally, Fox cut the most extreme scenes of Olivia de Havilland's treatment to get past the censors. They also included a written prologue explaining that all of the cast were actors and that the film did not reflect conditions in British mental hospitals. The film then won rave reviews in England and broke box office records.
The Committee of American Psychologists praised the picture for "awakening the public to the deplorable conditions existing in public institutions for the mentally ill" and gave it an award for "outstanding contribution by the entertainment industry to the field of mental health." In addition, the California Citizens Committee for Mental Hygiene gave the film a scroll, honouring it for awakening "millions to a greater knowledge and appreciation of the causes of mental illness."