Multiple Personality Disorder, or Dissociative Identity Disorder (DID), is an extremely rare mental illness. A person with Multiple Personality Disorder will have various, distinct personalities. The personalities will “switch” from one another, depending on the severity and environment of the person. When they do “switch”, that person will have complete control over the host, and personality switches can take either a few seconds or even a few days. In those days, the host will gradually dissociate and re-enter consciousness as their “alter”, or another one of their personalities. 

Those who suffer from DID almost always develop the condition due to past trauma, usually some kind of physical abuse as a child. A person develops the personality as a kind of protection, and one of the “alters” almost always has a protecting role. A person will switch to their “protective” or “tougher” alter when experiencing the trauma, as a way to block out the memories.

While those with DID do experience mood swings in response to switching personalities, it is not to be confused with bipolar disorder. Those with bipolar disorder experience severe mood swings, but it is not due to them switching personalities within their consciousness. 

The main form of treatment for dissociative disorders is psychotherapy. Talk therapy, counseling, or psychosocial therapy are other names for this type of treatment, which entails discussing your disease and associated problems with a mental health expert. Two very popular forms of therapy are cognitive behavioral therapy and dialectical behavioral therapy. Since there are no drugs that can be used to treat the symptoms of dissociative identity disorder, hypnosis has also been proven to be effective in treating this condition.