Anesthesia doesn’t put patients to ‘sleep,’ as they’re often told. Rather, anesthesia puts the brain into a state of unconsciousness that’s more like being in a reversible coma than being asleep, a new study says.

The study published in the New England Journal of Medicine on Thursday looked at how the brain behaves while asleep, in a coma and under general anesthesia. The brain activity of an anesthetized patient, for example, was more like a deeply unconscious coma patient than someone sleeping.

Studying the effects of anesthesia on the brain could have implications for diagnosis and treatment for sleep disorders or recovery from comas. This abstract and news release explain the findings more fully.

About 60,000 patients in the U.S. every day receive general anesthesia for surgery. Here’s what the Mayo Clinic says about when it should be used.

‘Your doctor may recommend general anesthesia for procedures that:

* take a long time;
* affect your breathing, such as chest or upper abdominal surgery;
* or require you to be in an uncomfortable position.