Please explain the following quote from "Macbeth". "Unnatural deeds do breed unnatural troubles:infected minds to their deaf pillows will discharge...

This is from Act 5, sc. 1 and it is spoken by the doctor who has been called to the Macbeth's castle to tend to Lady Macbeth.  He is saying that people who have done a deed that will cause them to have a guilty conscience, will suffer from the guilt that the deed causes, particularly if the "unnatural deed" is the rumored killing of the king.  He goes on to say that people suffering from such a guilty conscience are known to walk or talk in their sleep as a way of purging their minds of their guilty secret.  The doctor knows that rumor has it that Macbeth may have killed Duncan and others and he realizes that Lady Macbeth, knowing about or having a hand in these deeds, most likely suffers from a very guilty conscience.  He says, too, that Lady Macbeth needs religious intervention to help her mind and her soul, not anything he can give to her.  She doesn't have a physical problem, she has an emotional or mental problem.