I had a small surgery on my leg recently. I never mind seeing blood or anything, so during the surgery I was chatting with the surgeon, he was showing me the pieces ho just took out of me, etc.

But then out of nowhere I started to feel weird, the voices and sounds just became humming, my vision turned into a tunnel, I felt dizzy, I remember thinking "well, this is interesting" and then sort of going through a checklist in my head "hm, vision out", "hearing out", "brain stopping".

I squeaked something at the doctor and he immediately got me to a better position, got me water and I came to my senses gradually.

This was the first time in my life when I felt like fainting (and almost fainted). I was like wow, what an experience, what a weird feeling. After this I was shaky more than an hour...

I still wonder what exactly triggered this. I think it was my brain unconsciously getting into a spiral about seeing outside something that should be inside.