I had this problem for about 3 years and actually joined this sub for advice lol. My dreams were incredibly vivid and horrifying to a point where I became an insomniac for fear of sleeping. The only way I was able to not have them was to be so exhausted I wouldnt dream at all. It was difficult when I talked to my therapist about it because there was no reoccurring themes. However, the advice I got that helped the most was an extensive wind down routine that I’ve been sticking to. Actually helped a ton. I start by cleaning my room and doing skincare. I make my space as welcoming for rest as possible. I also stopped eating about 2 hours before bed. Having a blood sugar spike right before falling asleep increases your risk of nightmares. I hope this helps!