How can you sleep through an MRI?

I had my 1st MRI today.   The past couple of days I checked out sites like WEBMD and saw comments from people like "I slept through mine."

Um, how?

I had to hold my breath for 20 seconds then breathe normally, then repeat; throughout the entire thing.

No way to sleep having to do that.

Add the noise (which wasn't ear shattering, as they provided ear plugs for me) and again, no way to sleep.

Still it wasn't bad.   I am sort of claustrophobic, in the sense that if I can't see a source of air, I have a panic attack (needless to say the day I learned that airplanes have recycled air, was the day I started needing to be sedated to fly), so it was fine.  I just kept my eyes closed.

The only glitch was in having to drink that godawful stuff before hand.  Not that it tasted bad, it did, but after the second dose I started to shiver uncontrollaby for 10 minutes.  They checked vitals and everything and it was all fine.  And after 10 minutes it was gone.

Anyway, it's done.  Now I just have to wait for results to go  to Dr and for him to tell me, about a week, or so I've heard.