Need help when sedated, do you fall asleep or black out?

Technically both: Sedation uses medications that first cause a decrease in your responsiveness, then affect your memory so you don't remember the events around you, then can cause a deeper sedation that you might equate with sleep. It's not the same as sleep, but a way to depress your consciousness chemically.

Depending on the : Depth of sedation desire by the health provider you may feel just sleepy but answering simple questions (twilight) and the other end completely asleep without any recall of the procedure but not in general anesthesia.