Sarah,

OMG. I have experienced that. I just read up about it. Very interesting.

Karen,

I think I know what you mean. I have awoke from a sound sleep and my eyes feel very slow moving and when I try to move it's almost like I am moving in slow motion and I see trails. Weird I know. I dont know if this is what you mean or not but in any case I can relate to the visual disturbances. It doesnt happen all the time. Just as you said. If I am overly tired or stressed.
I hope it eases for you.