Fiona, you have my sympathy.
The problem lies in the way the cocktail of drugs they give you is supposed to work. (I'm a former nurse, btw.) It's only meant to produce very mild sedation, but total amnesia for the event. In fact, people who've had "sedation" often struggle violently and are more likely to have to be restrained during the process, as their higher intellectual centres are depressed by the drugs. However, they remember nothing afterwards, so it's as if they've had a GA. I always felt morally queasy about holding down someone who was looking me in the eye and screaming.
Last year it was my turn. I managed to swallow my large, spiky denture, which lodged in my throat. For three weeks I was kicked out of one hospital after another because it didn't show up on X-ray and they didn't believe me (doctors never believe their patients on principle!) Finally, very weak and dehydrated and 7 kilos lighter (every cloud has a silver lining!) I was taken to hospital by a determined friend, and a gastroscopy was reluctantly performed under so-called sedation.
I was very scared about this, as I know the over-65s suffer the most. They only give a half dose of the drugs to this age group, as they can suffer adverse cardio-respiratory reactions. I would have liked a GA, but was in no position to argue.
It was indeed a total nightmare. The denture was deeply embedded by this time and six people had to hold me down while they dug it out. I was in a strange mental state - almost like a wild animal. It felt as if my higher centres had been completely suppressed and the animal-like limbic system was in control. I knew what was going on, but still wanted to kill everybody.
When I was being wheeled out of the endoscopy suite, in a bed with the cotsides up, I was still under the influence and very angry. I remember kneeling up on the bed, clutching the rail at the head and screaming abuse in the nurse's face. I'd particularly taken against her as she'd been kneeling on my arm. She laughed and told me I was going to crash out any minute, I'd sleep from an hour and never recall any of this.
Well... judge for yourself! In the event, I was completely wired and didn't close my eyes for another 30 hours. (It's called a paradoxical reaction.) If I ever had to have another one, I'd insist on a GA. Fortunately, I live in a country where I'd be given the option of carrying the extra cost myself. I'm guessing you're in the UK, where the penny-pinching NHS response to such a request is likely to depend on your post-code.