Hamlet's Sanity

A big controversy in the play Hamlet is the question of Hamlet's sanity. Many people believe that in his faking of a psychotic breakdown, he actually went crazy. There is evidence in the play of this as he kills Polonius without considering the act at all. He seems to irrationally act, though throughout the previous parts of the play, he was known to act rationally. Many would say this is the perfect example to prove true insanity in Hamlet.
Others think that he never really was crazy. They reason that he felt that he had to kill Polonius to completely sell his insanity. Another theory that is present is that Hamlet got too in character and had difficulty pulling himself out of the mindset of psychotic behavior. I know that there are plenty of actors and actresses that go through this after they finish a movie production. They get so into character that their mind begins to believe that they are this person. A perfect example is Heath Ledger. He portrayed The Joker in The Dark Night. The character of The Joker was psychotic and could be seen as mentally unstable. It is believed by many that part of Heath Ledgers health decomposition before his death was due to the lingering character of the Joker. He had trouble coming out of character which led to sleepless nights, instability, and drug use. It is very similar to Hamlet, as he could not escape the character he was playing.
This is the stance that I would take on the subject. At first Hamlet was perfectly sane and rational. The thought out his whole plan and was prepared to execute it with perfection but did not take into account the possibility of forgetting who he really was. I think the death of Polonius was his turning point. He may have been attempting to sell is ruse once and for all, but even so, this is when he slipped completely into insanity.  However, I think he pulled out of it slightly at the end as he was dying of poison. I think he realized that he had gone too deep and should have taken care of his uncle sooner, rather than later.