Yes, this happens to me all the time. And I don’t remember to get up and go to the bathroom. I don’t even move enough muscles to keep my joints movable. I get up after 3-4 hours in the same position and I can’t even stand up straight. It takes some walking to get everything moving again. I have absolutely no sense of time even when I’m not hyper-focused. The hyper-focus just makes everything else go away. It’s a good thing I work from home.