here's a thought

 What if dreams, good and bad, are a warning from God that God alone will throw people into the lake of fire if they are not in the book of life.

The reasoning is that you can't stop dreams no matter what you do or pray. Just like you can't stop God from sending you to heaven or hell.

Even sweet dreams are horrible, because they are a violation against our free will. But God can do anything and no one can stop God.