Macbeth Act 5, Scene 3

Macbeth thinks that he will be invincible. He is convinced that until Birnam Forest comes to Dunsinane he will be just fine. He has no faith that Macduff is capable of defeating him. He thinks that there should be some kind of medicine to cure his wife's sleep issues, and he wishes there was a medicine to cure his country of the English. He has become very rash and demanding to those around him. This is a sign that he is a bit nervous. Deep down he is anxious about the battle, and this may come to blind him from the most important things, leading him to a defeat.