When Macbeth murders king Duncan he hears a voice that’s says “Sleep no more. Does murder sleep!” meaning that he only didn’t just kill the king but also he has killed sleep which means he won’t be able to sleep or rest. He will be drowned in guilt once he tries to sleep.
As a consequence of killing Duncan Macbeth becomes Paranoid. He thinks he hears someone laughing in their sleep and another crying Murder. “There’s one did laugh in’s sleep, and one cried “Murder!”
After Duncan’s murder and Macbeth is paranoid he starts having hallucinations and hearing voices which is important