In this Act, we see that Lady Macbeth is acting very strangely. A doctor is summoned to deal with her and witnesses her sleepwalking at night, obsessively washing her hands to try to get rid of bloodstains. This shows very clearly just how disturbed she is in her mind; she is unable to cope with her sense of guilt over Duncan's murder. In this way she betrays herself. Late, just before the climactic battle which sees the death of her husband, comes the news that she is dead. We learn from Malcolm's speech which closes the play that this was likely a case of suicide.
Lady Macbeth encouraged her husband to murder Duncan in order to achieve his ambition but both she and Macbeth pay dearly for this act; neither of them are able to cope with the consequences of their crime. Psychologically, they both break down.
Act V is the final act of Shakespeare's Macbeth and one in which both Macbeth and his wife encounter the negative consequences of their actions. In his quest for power, aided and abetted by Lady Macbeth, Macbeth has been responsible for the murders of King Duncan, Banquo, and Macduff's family. He has also become a harsh and cruel king.
Lady Macbeth, when she steeled herself to participate in the murder of King Duncan, discussed how such an act and the strength she needed to develop went against her inherently gentle feminine nature. This tension, between the practical need to be ruthless to act appropriately as a wife to Macbeth and further his career and her own moral upbringing and nature, lead to inner turmoil. She is especially guilty over her contribution to the death of Duncan. In Act V, this inner conflict and guilt gradually drive her insane.
The outward manifestations of this guilt are sleepwalking and a belief that blood is literally staining her hands and cannot be washed out. Macbeth hires a Doctor to care for her, but the Doctor suggests that she may actually need a priest instead. In Scene 5, Seyton notifies Macbeth that Lady Macbeth has committed suicide.
The news of death of Lady Macbeth was taken to Macbeth due to the shrieking of women. Her death was the simply the example of "poetic justice'. She has committed crime and evoked her husband to commit crime, so she spent her life in mentaly disturbed condition.
Further, this give the chance to patrachial Shakespeare to wrote one of his philosophies: "Life's but a walking shadow […] a tale told by an idiot full of sound and fury".