Hysteron, Greek for the womb, has encouraged a popular association between woman (womb-man) and hysteria. In fact, the phenomena we are dealing with here have in common only the fact that sometimes people act in such a way that they do not seem to ‘be themselves’[*] – or, rather, to have access to their most recent memories. The most common examples of such ‘hysterical dissociations’ are sleepwalking (somnambulism), hypnotic trance (on a variety of levels, including post-hypnotic suggestion), fugue (when a person simply wanders off, and turns out subsequently not to know who or where he is)[+], memory-loss (hysterical amnesia) – when people have finite, measurable gaps in their memory[#] – and split, dual, or multiple personality, when the subject is seen to change (at least ostensibly) from one person to another.
[The Home Encyclopedia of Human Psychology, ed. G. O’Bannon, p. 197]
Changing from one person to another (like >Doctor Who?)