I underwent a MRI scan last August - it lasted 40 minutes and as I was unable to focus on the inside of the machine, due to it's proximity, I closed my eyes and promptly fell asleep. The operator woke me up twice to ask if I was alright. Perhaps that was why your consultant said it was a good place to go for a kip!
Although I wouldn't say it was a pleasant experience (I do not suffer from claustrophobia), perhaps the apprehension is worse than the event.
Best wishes to "Mrs. Synthetic".