Verified answer

As B said, you give very few details. But if you mean the person comes out randomly and believe they are someone different, then this is DID, Dissociative Identity Disorder.

DID is caused by an extremely traumatic experience, usually during early childhood, and in order to cope with the situation(s) that otherwise could not be dealt with by the person, the mind creates a completely different personality in order to display or deal with the emotions that normally couldn't be expressed.

Everybody here is wrong (except for a few who said we can't really tell). There is nothing I can make of what you are saying. However we do see personality changes with extreme sleep deprivation. The quick answer is your brain cells start to break down because we do know, though hard science that sleep repairs cells in the body and brain. If you don't sleep at all the cells don't get repaired and they break down. There have been a few people who do not sleep at all, over months and they do die. We have found that their brains at the time of death loss 70% mass, they just about have no brain left. Something as simple as being nervous at parties will change your personality. This is on tiny link, image what happens when you loose a large mass of brain.

There are serious sleep disorders like i mentioned or just staying up too late can show an affect. A serious electric shock might show cortical damage but i can't confirm that.

But whatever happens is it not Split personality or Schizophrenia.

im not quite sure what youre asking, but ill try to answer. schizophrenia and split personalities are not the same thing. schizophrenia is when one cannot distinguish reality from fantasy and split personality is known as dissociative identity disorder. both of these mental illnesses are brought on by genetic dispostion and/or an extremely traumatic event in childhood, i.e., sexual abuse. neither of these conditions, nor any other mental illness can just develop overnight.

If it was caused by trauma or shock, it would be called 'Dissociative Identity Disorder.'

It's basically just what a person's mind does to forget about the certain trauma.

Many of the people suffering with DID move, get a new name, forget everything, etc..

It's pretty interesting.

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this could be many things....

yes almost anything is possible.

Psychology is a soft science and there is so many things that there are no definite answers, although science has come along way, there is a long way to go.

Is this something acute, or chronic?

Post traumatic stress disorder? I would only guess.

there isnt' enough information here to get ANY kind of picture about what may be wrong...