I too have very vivid dreams, strange and disturbing. At times I find myself crying in my dreams, and I awake sobbing. I wake up often with scratches, and i've bit myself once or twice. I've talked with my therapist about it and I started writing a dream journal. In my journal the pattern is with anxiety as Breakingtheshell mentioned.
I find that when i've been worried, stressed or anxious about anything I get into real nightmares that leave me physically scratched, crying and feeling very depressed.
I am not on medication as of right now, but have been in the past there is not connection as I can see in me. But we are all different and react differently. I try to meditate or do something creative before I find my way to bed, but sometimes thats hard to do with others needing attention as well. I hope you find calm and peace as you fall asleep.