In Charlotte P Gilman's "The Yellow Wall-Paper", how is the theme of identity used?

The Yellow Wallpaper was written in 1899, but describes a vivid transition and loss of a woman’s identity through illness, loneliness and growing despair that is as believable today as at the turn of the century when little was known of depression, paranoia or treatment for emotional stress.

The story is written in first person, in the form of journal entries, by a woman who has recently given birth and is not well. Her doting husband cares for her, but at the same time restricts her movement, communication and contact with the outside world.  Her psyche is represented by the increasingly threatening wallpaper in the room where she is becoming weaker and more isolated by the day. 

Each entry in the journal describes her increased disconnect with reality, no longer identifying with the world outside, but instead fixated on the intricate, never-ending design of the wallpaper  that she stares at all day. Eventually she sees a slight movement and then shadowy figures in the paper, ultimately losing her identity to the madness and loneliness as she becomes one of the creeping figures in the yellow wallpaper.  She gradually loses the decorum expected of women, especially the wife of a doctor and in those times.  The woman’s identity is transformed from one of recovering wife and mother to a shadowy creeping figure embedded in the yellowed design of the wallpaper in the room. The journal narrative artfully describes her decent into depression as her terror and “nervousness” increase and she imagines she become the creatures that she fears.

You can also track her attempts to maintain her various identities as wife, mother, writer, sister and woman, all in vain.  Along with this theme of identity, the author clearly advocates involvement, activity and interaction to prevent insanity.

Another interesting aside is that the author, Gilman, wrote that she had written the story because she had experienced a similar "cure" for "melancholia" that included total rest, no writing, and very little intellectual exercise.