Sex ..DREAM?

Okay...I am a virgin but I have been a victim with having dreams depicting me getting it ON. Why do I have these dreams?? I don't think about having sex anytime soon, or think about it at all. There's times where i sleep that I'm full on having sex and I orgasm then I wake up and question if I slept--masterbated? this has also happened in sleep overs, I wake up terrified thinking I fully got it on with someone in my sleep...lol. I think it's because I haven't masterbated in over a month? I've been in Mexico for some time now and haven't done it. Has anyone else experienced these explicit dreams??