I agree, general anesthesia feels like the closest thing we can experience. It's a little startling to go under, only to instantly wake up a few hours later and realize you just lost those few hours without even a trace. When you're asleep at night, you don't lose the sense of time, but under general anesthetic it's completely gone.

But I totally understand your point about how maybe it's just the amnesia part, maybe you do experience time, you just don't remember. I had the same kind of experience when I had a endoscopy, and I know that I had to be semi-conscious to participate in the procedure, but the time was completely lost to me and seemed instant, just like a general.