Dealing With Sexomnia

I started dating this guy. It's been less than a week. He got drunk last night and stayed the night. He wanted to mess around with me, but I wouldn't. He tried and realized that I wasn't going to change my mind, so we went to sleep. When I woke up at 7:30 a.m. his jeans were off and he was masturbating. He had previously put his hand down the back of my pants, but since my back was turned, I thought nothing of it. When I saw what he was doing I freaked out, got up and left the room.

He said he was sleeping, and doing this in his sleep. Possible or not? I don't see how it would be possible. To take your jeans off and do that, just seems like a lot of trouble for someone who is sleeping.