When I was put out for my wisdom teeth, I was really nervous about A. getting the teeth taking out and B. getting sedated, so they used a nice strong midazolam/fentanyl combo on me, which was nice. (Generally a benzo and opiate combo would be used for these procedures according to my grandma, who was a dental surgeon.)
They gave me a Ringer's lactate IV (just regular hydration fluids) for about 5 mins or so before starting. Then they started with the Versed (midazolam). Once that was injected via IV push, there was a 1.5 or so second time interval where I went from feeling a nice, warm, relaxing alcohol buzz feeling to total (but euphorically comfortable) unconsciousness (I wasn't actually unconscious, it just appeared so to me, hence the name "conscious sedation"; I could still interact with the surgeon and nurses apparently, though I have no memory of it whatsoever). When I hit the "unconscious" stage, I felt simply asleep, just like I do every night. I didn't dream however; I was just, well... asleep. Then I remember waking up in a recovery area, feeling slightly euphoric. I didn't feel any jaw pain because the lidocane they injected into the gum was still working. However, the midazolam causes quite astounding anterograde amnesia, so while I remember that I was awake and feeling supposedly normal, I can't remember to whom I talked in the recovery room or anything (one of my mom's work friends was there and I was apparently talking to her, but I don't remember it). After I got home, I took some Vicodin (5/325 combo; I have no tolerance) and slept. When I woke up two hours later, I felt perfectly normal (well, except for the pain radiating from my jaw

).
Don't let it scare you, the sedation is actually quite fun. After this is over with you'll be wishing you could get sedation meds all the time!

(well not really; if midazolam or fentanyl become abused, you'll be in for the addiction from hell)
Laughing gas isn't anything to worry about either, but it doesn't work that well on me.