Duncan, and ordering the murder of his friend, Banquo, causes him to have guilty hallucinations.
Lady Macbeth also hallucinates and eventually goes insane from guilt over her role in Duncan’s death.
he fact that both characters[M.LM] suffer torment as a result of their actions suggests neither Macbeth nor his wife is entirely cold-blooded.
Their guilt prevents them from fully enjoying the power they craved. Lady Macbeth says “What’s done/ cannot be undone” in Act Five scene one,
Macbeth’s guilt causes him to commit further murders in an attempt to cover up his initial crimes, Lady Macbeth’s guilt drives her to insanity, and, finally, suicide.
cost of guilt: sleep
Shakespeare uses sleep as a symbol of innocence and peace, it brings comfort and is an escape from the troubles of the real world.
Sleep is also used to express and reveal the subconscious and the conscience. Thus, sleep is denied to the Macbeth's after they murder Duncan.
Instead, their nights are plagued by nightmares and "restless ecstasy" (3.2), suggesting they relive their crimes every time they close their eyes.
Shakespeare uses imagery of light and darkness to explore guilt and innocence. Light is
a symbol of innocence, enlightenment, and often holiness, whereas darkness is
associated with the evil spirits that call for foul murder. Often, light and darkness indicate
which characters are guilty and which can be trusted.
Darkness used to conceal
Both of the Macbeth's call upon darkness to mask their crimes.
The darkness could be reflective of them turning their back on God and goodness and instead siding with temptation and the devil.