Catholics: Is this mortal or venial?

considered a mortal sin? I was sleeping last night and I got excited in my sleep and was touching myself. I saw a naked person in my sleep and I kept watching the dream and didn't wake up. Is this mortal sin? I didn't give full consent to it though because I was sleeping so does that make it venial? It is so hard for me to sleep without being excited a lot of nights. I am 20 years old so my hormones are still racing. When I am awake I always reject impure thoughts and I don't masturbate.