According to Brown, anesthetic drugs cause brain circuits to change their oscillation patterns in particular ways, thereby preventing neurons in different brain regions from communicating with each other. The result is a loss of consciousness—an unnatural state that he compares to a “reversible coma”—that differs from sleep. The oscillations vary, he explains, based on the type and amount of anesthetic used and the age of the patient’s brain (since brains age at different rates).