Working in the medical field, I've come across many people suffering from mental health disorder. One that really stood out to me was an elderly woman suffering from Dissociative Identity Disorder, also known as Multiple Personality Disorder. This disorder is where a person exemplifies the presence of two or more split identities. Each identity has their own age, sex, race and so forth. They even have their own mannerisms and distinctive way of talking. Sometimes they are imaginary people, or even animals.
When a different personality shows up, this is called "switching". This process can take any where from seconds, to minutes, to days. I can remember when the woman would "switch", sometimes it would be proceeded with a deep sigh and total relaxation of the body. Doctors believe this disorder stems from the effects of childhood trauma, mostly extreme and repetitive sexual, physical or emotional abuse. I thought it was cool to see her become "John". Her voice became deep and she had a thick southern accent.
Some symptoms include: depression, mood swings, suicidal thoughts, sleep disorders, panic attacks, phobias, alcohol and drug abuse, compulsions and rituals, hallucinations and eating disorders. More extreme symptoms are: amnesia, time loss, trances, and "out of body experiences". People suffering from Dissociative Identity Disorder have a tendency to hate themselves and can cause harm to themselves and others. They may find themselves doing things they wouldn't normally do.
Some people confuse Dissociative Identity Disorder with Schizophrenia, but they are very different. Even though they have similar symptoms, Schizophreniacs (yes, I created a new word) don't have multiple personalities. Statistics show that .01% to 1% of the general population suffers from Dissociative Identity Disorder, and that 7% may be undiagnosed.
There is no cure for Dissociative Identity Disorder and long term treatment is only helpful if the patient stays committed. Therapeutic measures may include talk therapy, psychotherapy, and hypnotherapy.