When I was little, I remember watching a scary cartoon or something, can't remember exactly what it was but I remember having nightmares.

3 nightmares in a row and I always woke up screaming.

I found (over years of trial and error) that if a bad movie or story made you upset, watch a cheerful or funny movie to "counter" it.

It's the best "medicine" I've found.

PS: too many psychs want to use the bi-polar stamp for some reason, bi-polar is actually quite rare.