One of the consequences of Cahalan’s experience with autoimmune encephalitis is how much she begins to question the nature of self, the nature of reality, and the nature of knowledge. In understanding and recounting what happened to her and how it affected those around her, Cahalan learns that human memory is a strange beast.

Cahalan experiences several moments where she hallucinates, is paranoid, and disconnects from reality. The most prominent of these states include her breakdown at her father and Giselle’s house, when she thought the pair had kidnapped her, her paranoia concerning Stephen’s fidelity, and her belief that the newscasters were talking about her on the television and that her father murdered his wife. While all of these instances reveal a disconnect from reality, the major incident that influences Cahalan’s understanding of her own identity is when she blacks out for a prolonged period in the hospital: “this was the beginning of [her] lost month of madness” (72). When she retraces her steps and watches videos from that time, now on the other side of recovery, she wonders how fluid or firm reality really is. To add to her confusion, many of the memories that she has from that time that she attributed to her illness, turn out to be real memories, such as the memory of the “Purple Lady” a nurse on her ward; “If all I remember are hallucinations, how can I rely on my own mind? To this day, I struggle with distinguishing fact from fiction” (242).