Mental illness is a key theme in this short story. Not only does mental illness shape the picture the reader receives due to the narrators perspective, but it also causes and leads to every conflict the narrator experiences.
What the narrator seems to suffer from is postpartum depression. She has just had a baby and is deemed 'hysterical'. Her husband claims they have rented a lovely country cottage for a few weeks to allow her to recover. However, it becomes clear upon a closer reading that she is in a mental institution, she even notices that there are bars in the converted nursery and how odd it seems. (She also is locked in her room and kept from writing or other things that could 'agitate' her).This is one of the first hints at mental illness. The next comes in the form of the wallpaper obsession and the people she sees outside her window. The woman imprisoned in the wallpaper represents our protagonist while the people outside represent the freedom she recognizes has been taken from her. While she is unable to fully comprehend that she is locked up in a room with barred windows because she is mentally unstable, she can comprehend that she does not like the situation and sees its strangeness.
Lastly, there are mentions of a divot in the wall from the woman in the wallpaper. As the narrator rips the paper to shreds in order to free the woman trapped in the wall, who actually represents herself. The narrator is the one leaving the mark in the wall. This is made clear as she says she circled the room continually, even after her husband came in and fainted from the shock of seeing his wife in such a state. Her shoulder has left this mark in the wall that she noticed in her diary. She also mentions scratches on the floor from the bed, likely also caused from her, as she struggled on the bed and from being restrained.
Clearly there are many subtle hints through devices such as foreshadowing and symbolism that paint the picture of a confused, mentally ill woman being held for something that was completely misunderstood. Based on these instances an example of a good thesis statement could be: Through the use of symbolism and foreshadowing the author displays mental illness and the stigmas surrounding it at the time, especially mental illness in women.
At the time that The Yellow Wallpaper was written and published, it was common for women to be diagnosed with a mental illness known as "hysteria." In the nineteenth century, hysteria was understood to be an exclusively female affliction.
One of the forms of curing hysteria was a method known as the "rest cure," which involved isolating a woman and forbidding her from "mentally strenuous" activities such as reading and writing. Instead, the woman was expected to participate in "domestic" activities, or she was confined to complete bed rest. This is the situation that the woman in The Yellow Wallpaper finds herself in. She has been diagnosed with "a temporary nervous depression—a slight hysterical tendency," and as a result, she is made to retire to an old mansion for the summer.
The woman and her husband move into the upstairs nursery. As part of her treatment, the woman is forbidden from working, despite her protests that she wishes to do so. She does not want to be isolated, particularly not from her child. However, as she has been deemed to be of unsound mind, her pleas are not taken as rational and are altogether ignored. The rest of the story details the woman's descent into madness. She begins to hallucinate, culminating in a vision of a woman trapped behind the yellow wallpaper of the nursery.
The Yellow Wallpaper therefore highlights the mistreatment of women by the male-dominated medical sphere of the nineteenth century. A woman could be termed "hysterical" for behaving outside of the norms imposed upon her gender at the time. This is why hysteria was most often diagnosed in women who possessed an education and women who were writers. It is also why the most common treatment for hysteria was to force the woman to live a "domestic" life, as befitting her gender. A woman was considered to be cured of hysteria if she became "subdued, docile, silent, and, above all, subject to the will and voice of the physician." Mental illness in The Yellow Wallpaper therefore serves as a realistic symbol of the oppression and lack of agency that women at the time experienced.