I had to have a bronchoscopy a few weeks ago
I'll be honest, there was one moment in the middle when the sedation stopped working and I woke up which was a bit horrific but then again I had the camera and wires in my lungs blocking all my airways so it's probably a different experience to having it in the stomach.
That being said it was a 45 minute procedure and that's the only thing I remember. If you have a brief moment too when the sedation stops working then they give you more straight away so 5 seconds later you're out of it again, it wasn't as completely horrific as I was expecting it to be.