Final answer:
Lady Macbeth's sleepwalking reveals her immense guilt and psychological distress over the crimes she's committed with Macbeth. The significance of her actions during sleep suggests that the subconscious is struggling with her conscious denials and repression of guilt.
Step-by-step explanation:
When Lady Macbeth appears sleepwalking, it is revealed that she is consumed by guilt and haunted by the crimes she and her husband have committed. She tries to wash the imagined blood off her hands, showing her deep psychological distress. Her sleepwalking signifies the subconscious mind grappling with the heavy burden of their actions.
She seems to relive moments such as convincing Macbeth to murder King Duncan and their attempts to cover up the crime. The significance of her revelations while asleep is that it portrays her vulnerability and the extent of her inner torment that cannot be expressed while she is conscious.
The play suggests a close link between guilt and madness; both Macbeth and Lady Macbeth start to experience hallucinations and mental instability as the weight of their guilt grows. Sleep, or the lack of it, becomes a motif reflecting the conscience of the characters. The act of sleepwalking reveals Lady Macbeth's inability to escape the moral consequences of their actions, suggesting that the mind cannot be at peace when burdened with such guilt.