When I was in high school I used to get nightmares so bad I was afraid to go to sleep. I started going nuts from lack of sleep, f**ked up my HSC, it was really bad I still get pretty scary nightmares occasionally but at least now I tend to forget them when I wake up, they don't play on my mind so much.

I find the thing that works best for me to avoid nightmares is to kind of start my own dream when I go to bed. When I lay down to go to sleep I start kind of daydreaming about something I like, imagining little scenarios in my head that turn into dreams as I fall asleep. It backfires sometimes though when I cant switch off and I end up laying in bed thinking about stuff instead of sleeping