“There were always in me, two women at least, one woman desperate and bewildered, who felt she was drowning and another who would leap into a scene, as upon a stage, conceal her true emotions because they were weaknesses, helplessness, despair, and present to the world only a smile, an eagerness, curiosity, enthusiasm, interest.”
― Anaïs Nin
The reason why the room was pink was because on black and white film, hues of red become dark shades of black. Pink is the perfect balance to give it that dark creepy grey.
A related fun fact: while old black and white film was under-sensitive to reds, it was correspondingly over-sensitive to greens. Actors whose characters were meant to have unnaturally pale complexions - like Morticia Addams - would often take advantage of this by wearing makeup with a green base tint in order to make their faces “pop”. This is where the modern trope of cartoon vampires having green skin comes from.