I never had, and it was a scary experience. They wheel you into a room with a Star gate in it, get you to lie down on this sliding table, and so you will fit into this tiny hole, they strap your arms to your sides tight enough to be uncomfortable. In your right hand they put a rubber bulb that you squeeze if you get into trouble. All it really does is get a response from the operator that your doing great and it won't be too much longer.
Time is relative.
Then they stuff you in this hole and you can't see anything except a neutral grey surface in front of you, which you estimate to be anywhere from 1/8" to 1 1/2" from your nose. Oh and they have put ear plugs in so you can't hear.
This tiny voice way off in the distance says "relax"
" breath in"
"breath out"
"hold your breath"
BANG BANG BUZZ SCREETCH HOWL BANG BUZZ WHINE BANG for about ten seconds, then
"relax"
Yup... no problem.
This goes on for what seems to be an hour and I complain.
"Your doing great Mr. Norwood... we are just about to inject the dye in, and that's the important part. You may feel warm all over, and it might feel like you are urinating"
Now, they have been giving me pee pills all week, and I peed before the procedure, but I really had to go again.
I started worrying about electrical shorts in the Star Gate. These things have their own transformers.
"breath in"
Breath out"
Hold your breath"
BANGBANGBANG SNAP SQUEEAL for 10 seconds.
"relax"
Over and over and over and over again.
No problem.
Finally they squeeze you out of the thing like a sausage machine, unstrap you, look disapprovingly at the "soak-er" pad they had you on, and say " you did really well. That happens a lot. relax".
Total time in the machine 1 1/2 hrs.
I hope the dreams aren't too bad.