Act II is the first act where Macbeth starts to hallucinate. Before killing Duncan, a bloody dagger appears into thin air. One can assume this is Macbeth's conscience warning him of the consequences he will certainly face if he kills the king. We once again see Macbeth's conscience come into play after he does the deed. He is so shaken and upset about killing Duncan that he cannot bring himself to go back into the hallway to plant the bloody daggers on the drunken guards. Some may say that there is some internal conflict with Lady Macbeth, as well, since she admits that she would have been able to kill Duncan, herself, if the king had not so much resembled her own father as he slept. One can also see the toll Macbeth's guilt is taking on him as he speaks with Macduff and Lennox about the murder of Duncan. He often speaks with disconnected sentences, showing how hard he is fighting to cover up his guilt.
In act2 sc.1, Banquo refers to some conflict in his mind relating to the prophecies of the witches:
Restrain in me the cursed thoughts that nature
Gives way to in repose.
Later in the scene, Macbeth sees an air-drawn dagger which, he knows, is 'a dagger of the mind', born of his 'heat-oppressed brain'.
In scene 2, as Macbeth returns from Duncan's bed-chamber after having done the deed, we find him miserably trapped in guilt and remorse. He regrets for having failed to utter 'Amen'; his tormented conscience forces him to believe that he " heard a voice cry 'Sleep no more!' ". Further on, Macbeth looks at his blood-stained hands to envision the conversion of the universal green into one all-pervading red:
What hands are here? ha! they pluck out mine eyes!
Will all great Neptune's ocean wash this blood
Clean from my hand? No; this my hand will rather
The multitudinous seas incarnadine,
Making the green one red.
Lady Macbeth's fainting in the 'discovery of murder' scene may also be understood as a manifestation of a deep inner conflict in the lady.
In Act II, Macbeth internal conflict rages as he knows what he has done is wrong. Macbeth is unable to rest and is constantly struggling with his conscience. He is consumed by rage, delusions and paranoia. This internal conflict is evident when Macbeth is unable to bless himself.
"One cried 'God bless us!' and 'Amen' the other;
As they had seen me with these hangman's hands.
Listening their fear, I could not say 'Amen,'
When they did say 'God bless us!'"Macbeth, Act 2, Scene 2, lines 36-39