Answer:
Nightmares in children may disturb them mentally and a child can individual develop the fear against a particular thing. Children can see fearful images and unrelated pictures in their nightmares.
The Millicent father is not completely right as she does not completely have nightmares. Sleep terrors might occur during NREM ( non-rapid eye movement) sleep. The main and typical treatment is to see whether the fear or terror go away by itself or not otherwise some extra treatment must be given to the child.