MODEL RELEASED. Anaesthetic sleep monitor. Anaesthetist Gavin Kenny (at right) with patient linked to a monitor that he designed. The monitor measures consciousness to prevent a patient waking up during surgery. It records the patient's brain activity in response to insclicking soundsins delivered through earphones. Electrodes on the patient's head record brain response to the insclicksins when awake, and when unconscious under the anaesthetic. This provides a scale of patient insawakenessins and their depth of unconsciousness. It is a more accurate assessor of consciousness than heart rate or breathing levels.