Ever since I was younger I have had this tic in a way in which I would roll my eyes to the back of my head almost as if I was having a 2 second seizure. Now that I m 18 it doesn t happen as often but occurs at least once or twice a day sometimes more and usually when I m tired. What could this be? And my identical twin sister does this as well. When we do it we carry on a if nothing happened as I am not aware when it is actually happening.