The most important thing to know about anesthesia in the context of OP is that it often doesn't work. 'Anesthesia awareness' is real and probably more common than we think because anesthesia can easily produce awareness but block memory formation.

Keep that in mind when they make arguments about propofol... Which is one of the drugs mentioned in https://www.theatlantic.com/health/archive/2017/12/surgical-... and https://gwern.net/doc/psychology/neuroscience/pain/anesthesi...

https://web.archive.org/web/20120411063647/http://squid314.l...

"What did the doctor say? He told me that they couldn’t up the anesthetic because an overdose could cause respiratory arrest, and that it wouldn’t matter because the anaesthetic on any dose caused severe short term memory loss and whatever happened the patient would forget all about it. The second point, at least, was right on. One patient spent the entire procedure writhing in agony and screaming something incoherent to God. The doctor finished the procedure, took out the endoscope, and cut off the anesthetic, and the patient turned his head, looked the doctor right in the eye, smiled, and said, laughing “Wow, that wasn’t bad at all! Guess I slept right through it!”"

Anesthesia appears to be a fairly broad effect - anaesthetics work on plants, for example [1], even though they lack any neural tissue whatsoever. It would be extremely surprising if those effects were also targeted enough to halt only some types of brain activity.

[1]: e.g. https://doi.org/10.4161/psb.27886

"Anesthesia" is a wider umbrella term than most people realize with many levels of sedation.

Under "general anesthesia", the patient is completely unconscious. They don't respond to any stimuli. In rare cases, some patients may have an adverse reaction and still retain some sensation, but that's very uncommon. My understanding is that we are certain that patients are actually unconscious (and not just unable to respond) because none of the other involuntary responses to trauma occur during surgery: elevated heart rate, etc. In short, you are simply not there for a while. This is what you get for most kinds of significant surgeries unless the surgery requires you to be awake (like brain surgery where they may need to ask you questions).

"Sedation" or "twilight sedation" is a lower level of anesthesia. You are somewhat conscious and can respond to commands from the doctor. But you are unable to form memories of what's happening and you're usually on something like fentanyl that makes you entirely OK with whatever it is they are doing to you. This is common for procedures like colonoscopies and endoscopies where the procedure is somewhat uncomfortable but where you aren't being cut open.

In general, anesthesiologists are trying to balance the goal of patient comfort against the risks of deeper levels of sedation.

More like very rarely (1-2 per 1000), very partially aware. I could not find anything saying that it was common, and it appears cases of actual awareness to the point of having pain / trauma are far rarer still. People who have this tend to have foggy memories or other concrete PTSD symptoms after the fact. It does not appear to be the norm.

I still think this experimentation is absolutely insane and I strongly object because there is no way to get feedback from the "patient" after the fact. Since we have no real idea of what is happening, I believe we should err on the side of caution. "But they could consent beforehand" is not morally acceptable for intrinsically inhumane actions that take away fundamental human rights and dignity. So if you think this is possibly inhumane / potentially torture, it is an irrelevant point since true consent would be impossible.

That's how twilight anesthesia works. That's the kind you get when having something like wisdom tooth removal or an endoscopy. They want you to be responsive to instructions but completely relaxed and unable to form memories of the event.