Throwing and hitting in my sleep

When I'm sleeping I usually throw things in my sleep, I knew this but one day my friend spent the night and in the morning she told me I back handed her upside the back of her head. Another time when I spent the night at a friends house I was sleeping on one side of the room and another one of her friends was sleeping on the other side and when I woke up I saw that the pillow I had was on her face. Is it normal that I throw stuff and hit people in my sleep?