Dear M,
Not to worry! We cannot be tempted to sin when we sleep because we can’t sin in that state. At such times we do not have the use of our free will. Now we may have dreams of things that would tempt us when we are awake. But they are not temptations while we are sleeping.
Dreams tend to be highly symbolic, although there have been times when God has spoken to people in their sleep either directly or through an angel. When this happens, the person knows that God has spoken.
Fr. Vincent Serpa, O.P.