Not an expert, but I seriously doubt that having nightmares every night is normal.
It could be some mundane cause.
I, and almost every grown up has your basic "anxiety nightmares" now and again.
You are either dreaming that you're back in school, and are flunking out, or that you're a teen again and you're a new driver, and you just clipped somebody's fender in the mall parking lot, and now your dad is gonna eat you alive when he finds out!
If thats the kinda dreams you're having then its usually because (a) you dont have enough blankets on your bed, or (b) you needed to take a leak while you were sleeping. Both cold, and holding in urine causes your body to tense up. So your mind generates a story to explain why your body is tense, so it creates a story around anxiety because anxiety also tenses up your body.