Lady Macbeth, so remorselessly wicked earlier in the play, when she pushed her husband to commit the horrible crimes necessary to fulfill what they saw as his destiny, is by Act V a shattered woman, consumed by guilt. Shakespeare conveys this sense of guilt through a famous scene in which Lady Macbeth, sleepwalking, frantically scrubs at imaginary blood stains on her hands:
Out, damned spot! Out, I say! One–two—
why then ’tis time to do't. Hell is murky. Fie, my lord, fie!
She goes on to specifically reference the murders of Duncan, Lady Macduff and Banquo, and to observe that "all the perfumes of Arabia would not sweeten this little hand," or cover up the smell of blood that has accompanied her husband's rise to the throne. At the end of the scene, the doctor who has witnessed these disturbing developments along with Lady Macbeth's Gentlewoman, observes that clearly the tormented woman has seen more than she should, and that something is wrong in Scotland:
Foul whisperings are abroad. Unnatural deeds
Do breed unnatural troubles: infected minds
To their deaf pillows will discharge their secrets...
In other words, the Doctor and the Gentlewoman reinforce the conclusion that Lady Macbeth's sleepwalking episodes are the result of her guilt at the bloodletting that she and her husband have brought about.