Lady Macbeth spends the majority of the first acts displaying a masculine quality, her control over her husband much greater than most would expect for the time period and his station. She is certain and sure in what they must do to gain the titles she desires, particularly after she is emboldened by the witches and their prophecy.
However, after the murder occurs, she seems to lose her constitution over it, and begins to sleep walk. Her tone in this scene varies between fear, regret/guilt, and even still her imperiousness towards her husband. She comments on the invisible stain the king's blood left on her hands, which was ironic because earlier in the play she told Macbeth that a little water was all that was required to wash it away. The blood has a deeper meaning, indicating the king's family--his son, Malcolm, is out for revenge. The guilt remains with the false queen as she continuously comments on the fact that the blood is still there, condemning her.
Yet her imperiousness continues to show in her words as she tells Macbeth to be calm and stay steady. Part of her sleep talking refers to the night of the murder itself, while still other parts seem to indicate she suspects what is coming.