Jenny, 4 weeks ago I had a gastroscopy (down) and colonoscopy (up) one after the other, and I have to say it was unpleasant. After the change of diet 2 days before, you then have to purge yourself - in my case this involved taking Picolax twice, and on both occasions it took about 4 hours to fully 'detonate'
I would advise your friend's brother to have as much sedation as he's offered, as what I was given seemed to have no effect at all. They put a canula in my arm and some midazolam for the gastroscopy, which felt like they were forcing a garden hose down my neck. I was topped up with Buscopan AND Fentanyl for the colonoscopy, but again it had no effect, and I could feel every twist and turn of the wretched shuftyscope. I had to ask to hold the nurse's hand!
They say you have to have someone pick you up, stay with you overnight, and that you musn't drive or sign documents. But so aware was I in spite of the above sedation, that as I was sitting with the cup of tea and biscuits they give you (which I was so grateful for, as hadn't eaten for 36 hours)I was able to remember and complete the final clue of the Private Eye crossword I'd started in the waiting room!
Sorry to sound so negative, but it was horrible. The discharge nurse said some people choose gas and air - which I had not been told about - but I would ask for the max they can offer.