Art by smbc-comics
Consciousness is often said to disappear in deep, dreamless sleep. We argue that this assumption is oversimplified. Unless dreamless sleep is defined as unconscious from the outset there are good empirical and theoretical reasons for saying that a range of different types of sleep experience, some of which are distinct from dreaming, can occur in all stages of sleep.
Pubmed Articles
Does Consciousness Disappear in Dreamless Sleep?
Sciencealert Article We Were Wrong About Consciousness Disappearing in Dreamless Sleep, Say Scientists
That is an interesting philosophical question.
If suffering is not remembered, was there even suffering? And if there was, does it matter? I can think of a few counterexamples of that, for example: a killer who tortures his victim before killing them.
Physical abuse tends to leave some physical consequences. You'd have to come up with an example where there would be neither physical not psychological consequences... but even getting anesthesized against one's will is already a consequence.
That article is a mix of several cases.
One of those you might call going against the wishes of the patient... then again, that's quite common in the ER, patients are yet to be established as "sound of mind" and capable of deciding for themselves, so an ER doctor can overrule them, including sedating to perform any procedures they consider necessary.
Others seem like letting students perform a non-vital part of a procedure, which is both expected from University/teaching hospitals, and in my personal experience was spelled out in the consent form (although they never told me personally, so if I hadn't read it, I wouldn't know).
None of those are. Communication could be improved, and I personally get pissed when medical personnel switches from "medical adult talk" to "patient baby talk" right in front of me... but I've also seen patients get upset because they didn't understand what was being talked about, and had to be calmed down with "baby talk"... so it's a difficult issue overall.
Presumably in your scenario the victim remembers the torture though.
In the case of general anaesthetic the memory is effectively considered to be deleted in real time. On its way through the brain it ceases to exist so it never reaches the conscious mind.