Consciousness under the knife, it turns out, may be much less common than researchers once suspected. Anesthetic awareness—being conscious during surgery but unable to move or alert surgeons to the problem—sounds like a scenario out of a horror film. But while previous studies indicated that around one in 500 people experience it, a new study found that the number sits more around one in 15,000 and that the experience rarely causes pain.

HealthNews describes the phenomenon:

Insufficient quantities of anaesthetic reach the patient for a number of reasons, including equipment failure and incompetence on the part of the anaesthetist. Because a paralysing agent is used for ease of surgery, the unfortunate victim is unable to move a muscle and thus unable to alert the operating team to their plight. Consequently, they are forced to endure the pain of every slice of the knife. The resulting trauma has been likened to that experienced by torture victims and can cause life-long damage.

To arrive at these new conclusions, the researchers surveyed more than 80 percent of anesthesiologists in the UK. They asked the anesthesiologists about any cases of accidental consciousness during surgery, finding just 153 cases out of approximately 3 million surgeries during 2011. The BBC elaborates:

Most of these patients either came round too soon from general anaesthetic or took too long to go under. A third – 46 in total – were conscious throughout the operation. According to the anaesthetists, very few patients suffered any pain or distress as a result of the experience.

But that’s according to the doctors. Patients report a higher rate, the Los Angeles Times reports:

The doctors reported…a rate of incidence between one out of 12,500 and one out of 20,000 — much lower than the one or two per 1,000 anesthesias reported in recent patient questionnaires, wrote lead author Dr. Jaideep Pandit and colleagues. That discrepancy could be due to underreporting by doctors, reticence to speak up on the part of patients or other factors, the team wrote.

The researchers are conducting a follow-up study to learn more about the people who did have to sit through their surgery in the hopes of avoiding those incidents in the future.

More from Smithsonian.com:

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