In what ways does Shakespeare call on the images of light, of sleep and of blood to emphasise Lady Macbeth's state of mind in Macbeth?
This is in Act 5 Scene 1. It's when the doctor and gentle woman witness and talk about Lady Macbeth's actions.
Shakespeare also uses the conversation between the Dcotor and the Gentlewoman to convey images of light and sleep. When Lady Macbeth enters sleepwalking they have this exchange:
How came she by that light?
...She has light by her continually. 'Tis her command.
You see, her eyes are open.
Ay, but her senses are shut.
Shakespeare makes a connection between light and sight through these rather minor characters that illuminates Lady Macbeth's state of mind. Even though she has light and her eyes are open, her senses (her true means of awareness) are shut. So, it might be observed that Lady Macbeth is stuck, sort of like a broken record, unable to use the light to see her own past cleary and feel remorse; but also unable to accept her deeds and rest easily at night, and sleep.
The images all add up, in the Doctor's estimation, to the need for religious salvation. At the end of the scene he concludes:
More needs she the divine than the physician.
God, God forgive us all!...
And still keep eyes upon her....
My mind she has mated and amazed my sight.
So, the connections between light and sight, between looking and really using the senses that the Doctor and Gentlewoman start the scene underscoring are reiterated here.
In Act 5 Scene 1 of Macbeth, Lady Macbeth has gone mad with guilt, now feeling the weight of the responsibility of her actions. She continually has a light next to her to symbolize that she can now "see" what she has done wrong. She appears to be sleep walking, but she is "awakened" to the wrongs that she has done, and she now admits her role in Macbeth's schemes. Lady Macbeth continues to say "Out, damn spot!" thinking that there is blood on her hands, but this blood is a symbol of her guilt. In this scene, Lady Macbeth leaves behind any sense of innocence that she may have previously felt, and she accepts the responsibility of her actions.
In Act 5.1 of Shakespeare's Macbeth, Lady Macbeth, after her deep involvement in the murder of Duncan, which leads to the murders of Banquo and Macduff's family members, is afriad of the dark (the candle, light), cannot sleep (sleepwalking), and cannot get the imaginary blood of Duncan off her hands.
In this scene, the light imagery reverses imagery from earlier in the play, when the Macbeths wished to have their deeds hidden and unseen. Lady Macbeth has now lost the ability to sleep, as Macbeth did long ago and as was predicted when he heard a voice calling out that he has murdered sleep. And Lady Macbeth now is obsessed with the blood of Duncan on her hands, as Macbeth was right after the assassination. In a play filled with role reversals, Lady Macbeth has not become the aggressive, macho male who doesn't feel pity that she wished to become. She now experiences the symptoms of guilt that Macbeth felt right before and after the assassination.
Lady Macbeth's state of mind is the reverse of what it once was, and her state of mind is most fully revealed in her Obsessive Compulsive Disorder-like failure to rid herself of Duncan's blood, which, by the way, Shakespeare depicted almost 400 years before doctors even began to understand OCD.