We've nearly all been there at least once - awakened with a pounding heart and the memory of frightening scenes that seemed so real, but were conjured up and existed only in the sleeping mind. Nightmares affect people across countries and cultures, with some 10 percent of the world's population reporting recurrent nightmares. Parents have reported, and science has recorded, nightmares in children as young as 18 months old. Up to 40 percent of children...