Lady Macbeth is disturbed, meaning mentally deranged, in several ways. First of all, she is highly ambitious. She does not care if she deserves what she wants, she just wants it. Second of all, she is violent. She thinks nothing of murder. Finally, she is wracked with guilt from her deed.
First, Lady Macbeth is ambitious. When her husband writes her a letter saying that some witches suggested he might be promoted to Thane of Cawdor and then king, she seems latch right on to the idea. She is completely ready to make him king, even though he is not the king’s successor.
Thou wouldst be great;
Art not without ambition, but without
The illness should attend it. What thou wouldst highly,
That wouldst thou holily; wouldst not play false,
And yet wouldst wrongly win. Thou'ldst have, great Glamis, (Act 1, Scene 5, p. 19)
She seems to think that her husband is too nice, and lacks ambition, and therefore he won’t get what he deserves. She decides to give him some motivation.
Second of all, Lady Macbeth is violent. As she convinces her husband to kill Duncan so Macbeth can become king. She uses very violent imagery.
I have given suck, and know(60)
How tender ’tis to love the babe that milks me:
I would, while it was smiling in my face,
Have pluck'd my nipple from his boneless gums,
And dash'd the brains out… (Act 1, Scene 7, p. 24)
She describes nursing a baby and then bashing its brains in. Not a pretty picture, and certainly not the product of a stable mind.
Finally, Lady Macbeth’s instability really comes out after she sees the consequences of her actions. She basically loaded her husband like a weapon and pointed him at Duncan. She also created a monster, because he goes on a murdering rampage to secure his place. He kills Banquo, Fleance, and Macduff’s entire family. She shows both remorse and fear at discovery.
Out, damned spot! Out, I say! One–two—
why then ’tis time to do't. Hell is murky. .. Yet who would
have thought the old man to have had so much blood in(35)
him? (Act 5, Scene 1, p. 77)
Lady Macbeth goes into a kind of trance, sleepwalking and confessing to murder. Soon after, she kills herself. She cannot bear the guilt any longer.