I have had it happen because of my dissociation problems and also because of the medications I was on. recently my psychiatrist put me on prozac and all I could do was sit there and watch what was going on. I couldnt participate because I felt so separated from my body I couldnt figure out how to make myself do anything but watch. My arms and legs felt so numb and miles away like they werent even attached to me. and looking at objects I could not judge distance. go to pick up a glass for a drink and missed it because through my eyes it was like looking through a tunnel. I ended up being taken to the er because I had cut myself trying to make myself feel and get back into my body. My psychiatrist took me off prozac and things went back to normal with me being inside my body again.