In a foreward to a new report published by The Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland, a woman identified only as “Sandra” describes being conscious during an orthodontic operation, while under anesthesia.
Suddenly, I was aware something had gone very wrong. I could hear what was going on around me, and I realized with horror that I had woken up in the middle of the operation, but couldn’t move a muscle. I heard the banal chatter of the surgeons, and I was aware of many people in the room bustling about, doing their everyday clinical jobs and minding their own business, with absolutely no idea of the cataclysmic event that was unfolding from my point of view.
Nearly four years of research into every hospital in the U.K. and Ireland, as well as 300 anecdotal reports, resulted in this, the largest survey of “accidental awareness during general anesthesia” (AAGA) to date. The editors of the report explain in their introduction that both anesthesia and human consciousness itself are not well-understood, and so, "historically, when faced with a report of AAGA, there was a tendency to disbelieve the patient’s account." And when the phenomenon does occur, there's only one person who really knows what happened—the patient. This project was an attempt to deepen understanding about when and how AAGA happens.
The report estimates that these incidents occur about once in every 19,000 uses of anesthesia. (In a feature for The Atlantic, Joshua Lang reported a higher number—one or two per 1,000, in the U.S.) Different surgeries have different risks—C-sections, for some reason, were the most common, with an incident rate of one in 670.