Oh, I'm so glad you posted! that's pretty much what I experience also. I get really sleepy, not the kind you can fight. Most of the time, I give in... I also get tunnel vision and certain sounds are very much intensified. In addition, I start getting this wavy sensation all over my head (I guess it's in my brain...) which is really tough to describe. It takes me a while to feel grounded again, and once it's triggered, i sort of get aftershocks. It's good to see someone else describing what I go through. Thanks!