I've been generally anaesthetised about 15 times in my life. Sounds a lot, I suppose, but I am rather long in the tooth, and have been exposed to some risks.
Back in the 1950s and early 60s my dentist would not administer locals, so I had several experiences of general. I found the sensation of losing consciousness very unpleasant indeed. There was no pre-med injection, just straight into the breathing procedure with a mask over my face. I had a semi-conscious sensation of my lungs being supercharged when I breathed in; it was almost as though my lungs would burst on every breath, then just before they did I was able to exhale, but of course I was faced with the next bursting intake of breath. I also had a sensation of rapidly spinning backwards. I was rotating around a horizontal axis placed from side to side just under the seat of the chair, and I felt as though I had to cling on to the arms of the chair. The sense was similar, I later learned, to doing aerobatics. These sensations appeared real to me, and as far as possible in other dental operations I would go without anaesthetic as much as I could - and this was in the days before modern high-speed dental drills !
Speculating on the sensations in later years, I have guessed that the chair spinning may have been an illusion started off by being laid further back to a lying down position as unconsciousness started. The lung bursting sensation, well, I don't know, but maybe dental patients had to be given a hefty single dose in order to be "kept under" throughout the whole procedure, as the nature of the surgery meant that ongoing administration of the gas via trachea was impossible.
My next experience of GA was in late 1960. I had suffered a very nasty compound fracture of my forearm. Displacement of about 90 degrees at about the mid-point of both radius and ulna, with all four broken ends projecting through the skin. It was very painful and shocking, and unfortunately for me I had to go several hours without pain relief. It was such a blessed relief when I received anaesthesia that any negative illusory sensations were hardly a concern. The operation on my arm required the debriding of skin and muscle around the wound site (i.e. the removal of mashed up soft tissue to prevent gangrene), and I still have a large ladder scar, and a hollow in my arm, where this was done.
Moving on to about 1965. I developed an abscess in my throat which was painful, but I tried to ignore it as I was on an Army course which I was keen to complete. However, one morning I awoke unable to speak. Strong antibiotics worked, but I was told that any further delay in treatment might have caused blockage of my trachea, and death through asphyxiation. It was subsequently decided that I should have a tonsillectomy to prevent any recurrence (as I had also suffered from regular tonsillitis on a few occasions.) This operation was carried out in a military hospital in England. I awoke on the operating table. I could not see, but I could feel pain in my throat, and I could hear; somebody said "He's a big chap, should have given him more." I was able to flex a knee and draw up a leg, and felt a pair of hands hold it down. Then out I went again.
When I mentioned this later, it was denied. A fierce ward sister with captains pips and Second World War medal ribbons on her cape told me it never happened.
After that, a few more fractures, ### nasal bone, and a couple of Bennett's Fractures (hand bones, typically suffered as a result of punching something.) I had one of these Bennetts done at a civilian hospital, then another at an RAF hospital in England By now, pre med injections were being given before general anaesthetic and the whole procedure wasn't bad. The pre-meds of those days had a reputation for making you feel a bit woozy.
The RAF also carried out an operation on me in Germany to replace facial bones in the right place after several injuries. What I remember about the anaesthesis on this occasion was that I had cocaine administered up my nose a few hours before going under the knife ! Apparently this was mainly to restrict local blood flow, but I have to say that I enjoyed the sensation and I could understand why people of weak character would take it recreationally, though I was never tempted to do so.
A couple of years back I had general anaesthetic for a double inguinal hernia repair. I was given an injection in the back of my hand, and was told that I would feel an ice cold sensation radiating out from the injection site. I hardly had time to acknowledge, and the next thing I knew I was coming round in a recovery room !
These are my experiences.