I've had an endoscopy with no sedatives/anesthetics etc. It was definitely not fun but doable. As soon as the scope went down my throat I went into panic mode. My heart rate was through the roof, and I couldn't stop retching. But after it passed that initial gag reflex point, it settled down. The nurse holding my hand holding my hand soothed me as well.

Then I got up, walked to my car and drove myself home with my brain at 100% (albeit with more adrenaline and cortisol than normal).